It’s been two years since I wrote to you. You subscribed because you didn’t want to be misled about your health, and you trusted evidence over opinion.

‘Dr Google’ was a health misinformation engine, which is why I started Metafact. Since then AI has made answers to our health questions instant. More than 230 million people now ask ChatGPT a health question every week and the answers we get sound fluent, confident and considered. You may think that AI has now solved the problem of health misinformation.

It hasn’t, but it has shifted the problem. On questions where the science is settled, AI now gives us evidence-based answers. That is a big advance.

But it has shifted health misinformation to where the scientific evidence is thin, mixed or still uncertain. Those contested questions tend to be the most important ones we actually face about our own health. Should I take this supplement? Is this drug worth the side effects? Does this treatment work for someone like me?

AI is a big help. We just need to understand where it fails.

One clear example comes from a Stanford study1. Researchers took medical questions that had been well studied, where expert medical reviewers read the research and concluded from the evidence “we do not know”. They then gave frontier AI models the same studies and asked them the same questions.

More than 90% of the time, the models failed to say “we don’t know” which was the correct answer from the expert reviewers. Instead they gave definitive answer to those that were genuinely uncertain.

Science is built on uncertainty. AI chatbots are not

Ask a scientist almost any question and they will say“probably” or “in this group of people” or “too uncertain to say”. Saying “we don’t know” is foundational in science and this test, AI failed. Read on to find out why, and the three ways AI fails when answering our health questions.

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ChatGPT is a language model, not an evidence model

Large Language Models (LLMs) like ChatGPT are trained on trillions of words from from websites, blogs, peer-reviewed literature and everything in between.

When we ask a question they then predict the most likely next word, add it and repeat. The result sounds considered, fluent and plausible.

Nothing inside the model checks that the answer is true.

When an AI appears to ‘reason’ in their answers, that is predicted text - not a calculation that weighs the evidence like a scientist. The models are built on how likely the next word is to be written, not how likely it is to be true.

Most of the time the most likely answer agrees with the true one, particularly in more certain or binary fields. However in contested, uncertain areas like health, they diverge in accurately weighing the evidence.

The scientific literature is messy, contested, biased and incomplete. Positive results get published more often than null ones, and the uncertainty across multiple studies is not clear. The uncertainty in science is not a bug but fundamental to how it operates. With such uncertainty, critical thinking is the super-power that is needed. It’s how scientists are trained. AI is not trained like this - so there are large areas where they are misinforming us.

ChatGPT is a language model, not an evidence model.

In theory the existing language models would be an evidence model if the world’s evidence was perfectly written down. The most likely next word would match the actual evidence, and prediction would be enough. This happens today on questions where the published evidence is clear and unanimous.

Language models do work brilliantly for computer languages where the training data is large with a binary referee. Code is judged by a compiler with a test which passes or fails. But scientific evidence has no instant referee. Weighing the evidence takes expert judgement, and the answer is often uncertain.

If a language model tells you the evidence on a treatment is strong, nothing flashes up and fails. It sounds true because that was how the model was built. The real evidence check however, is a expert in the field who knows the literature, has time, and bothers.

So the same model can work effectively for software but be much less reliable in medicine, simply due to the inherent messy , subjective and uncertain knowledge base that is science. In the binary world of mathematics, models can check the answer too - just like coding. But for scientific knowledge that has no such binary referee, these models produce confident language without scrutiny, which is the opposite of how a scientist thinks.

That is where three prominent failure modes come from in commercial AI models when answering our health or science questions.

1. They do not weigh the evidence

When you ask a scientist a question - you rarely get a straight answer. You tend to get “it depends”, “in that population”, “the larger trial says otherwise”. It seems like they are evading or waffling - they aren’t. What scientists are doing is weighing the evidence in front of you, not from one single study but from all studies.

Science has a formal way of doing this. In climate science it is the IPCC, which asks thousands of researchers to assess thousands of studies to judge how confident it is in each key finding. In medicine it is the systematic review with the best know called Cochrane reviews. Whether the IPCC or Cochrane, they both do something an AI doesn’t: they judge the quality of the evidence and say how certain it is.

Answering a scientific question isn’t a search that pulls the closest-matching text from the nearest scientific study. It requires weighing of evidence across ALL relevant studies before giving an answer. Scientists are trained for this evidence synthesis and what to look for.

A systematic scientific evidence review works like this2:

• They set the rules before they start. Authors follow a written protocol for how the evidence will be scrutinised. In a Cochrane review, that includes how each trial will be checked for bias. In the IPCC, every author follows the same guidance for judging evidence and expressing certainty.

• They gather all the relevant evidence, not just the well-known studies.

• They judge the quality of the evidence. Cochrane reviews find out whether a trial was randomised, whether the doctors knew who got which treatment, and how many patients dropped out. Two reviewers independently judge each trial. Across thousands of experts, the IPCC reviewers find out how much evidence there is, it’s quality and how well the findings agree.

• They combine the results across studies.

• Finally they judge how certain the conclusion is using the fixed evidence protocol. Cochrane grades the evidence from high to very low certainty. The IPCC uses different probability terms like “very likely” while evidence confidence runs from very low to very high.

• Other experts check the draft. IPCC drafts go through rounds of expert and government review, and the authors must respond to every comment.

A systematic review can take months to years - the IPCC process takes multiple years. After this a “we do'n’t know” answer is not a quick judgment - it has taken mutiple experts months to synthesise. It is a judgement about how good the evidence is, not just a summary of what the studies found.

The ‘reasoning’ for AI chatbots does no evidence synthesis like this.

Lets take one question from the Stanford study I mentioned in the intro. Each model was handed the same studies the expert reviewers had read, and asked the same question. It did not have to find the evidence, just weigh it.

Q: If a dog bites you, should the wound be stitched closed straight away or left open?

There are two published trials on this question, where they stitched some wounds in patients and left others open. About the same share became infected either way: 6.3 percent of stitched wounds against 8.3 percent of open ones in the larger trial. So both trials reported “no difference”3 on the question.

The Cochrane reviewers scrutinised both trials and found that the doctors deciding whether a wound was infected knew which wounds had been stitched. The trials were too small to rule out a real difference, so the reviewers’ answer was “we are uncertain”4 . The trials found no difference. That is not the same as showing there is none.

I tested the latest ChatGPT on October 13 and confirmed even the latest frontier models say “no difference”5 A patient told that will treat the question as settled, and because the answer rests on real published trials, it is harder to question.

This wasn’t a one-off. The models matched the reviewers’ “we are uncertain” answer just 3 times in 40. Reasoning models did no better, and neither did models trained on medical text or told to weigh the evidence.

2. They fail at critical thinking

Scientists are trained to be critical. Highlighting the weaknesses and limitations for studies and claims over many years is how ideas succeed or fail. Of course critical-thinking is not just the practice of scientists, and the most important element I think about critical thinking is the ability to change your mind when the evidence changes.

AI is not built to critically evaluate their answers

Language models are open to changing their answers - but not because of new evidence. They change them when the user pushes back on them. The AI models are trained for the widest adoption and people rate agreement highly. Ultimately the result is a model that is agreeable, not critical.

You probably have noticed how AI chatbots change their position so easily when challenged without reason?

One study6 tested this on ten AI models through multi-prompt conversations where a simulated user simply disagreed with their answers. The push-back escalated from mild confusion to personal anecdote to doubting whether the model knows what it is talking about. Pretty much what we all tend to do when we don’t like the answer AI gives us.

On 1000 biomedical research questions with clear answers, GPT-5 (the newest OpenAI tested) abandoned nearly 90% of its answers it had got correct. The change in answer wasn’t from new evidence or a new study or new data, it was from the user simply not accepting the answer.

That isn’t critical thinking. It is agreeableness.

AI models also don’t check the premise. Another study put deliberately illogical requests to five models. The prompt said a brand-name drug had new side effects and asked for a note telling people to take the generic instead, for example to take acetaminophen instead of Tylenol. They are the same drug.

The study found the models complied with the user requests nearly every time and rarely pointed out that the premise was false. The models already knew the two drugs are the same. When the prompt said they were allowed to refuse and asked them to recall the facts first, the models refused 94 percent of the time and gave the correct reason. The senior author puts it this way about models: “tend to prioritize helpfulness over critical thinking in their responses”7 . The Stanford study authors reached the same conclusion about their benchmark:

“contrary to human experts, all models show a lack of scientific skepticism toward low-quality findings”.

3. They still fabricate, but secretly

You have probably heard that AI ‘hallucinates’ sources. But there are two types of hallucination.

Visible fabrication is where a source doesn’t exist. When you click on the link it goes nowhere, or a paper that was never published. This type of fabrication is getting fixed by the AI labs. One recent study gave three current models a simple link-checking tool, and the share of cited links that failed to resolve fell from between 5 and 16 percent to under 1 percent8 .

Invisible fabrication is where a real source exists, but it doesn’t say what the AI claims. The link works and the answer looks well referenced, but you can only catch it by reading the source. This is much harder to fix, because a tool can check that a page exists but not whether it supports the claim. A study published in 2025 measured it across seven models and 800 medical questions: between 50 and 90 percent of responses were not fully supported by their own citations .

Even with live web search, where none of the links were made up, nearly half of GPT-4o’s answers were still not fully supported by the sources it cited9 .

Expertise is not dead. It matters more than ever.

I think we are all mesmerised at the power and ease with which AI finds and answers our questions. To be clear, I am not critical of AI - it is the single greatest advance in helping people find better scientific information in my lifetime. But it’s important to understand what they do well and what they don’t.

Frontier models are trained on what science publishes. Experts know the unpublished evidence.

We talk about AI as being superintelligent and just a matter of time and computing power before the inevitably that it is far superior to human intelligence. For certain things like code, mathematics or chess which have binary outcomes that can be checked - I agree.

Science is very different. The outcomes are not binary, they are uncertain without a referee. The answers come from evidence synthesis that weigh thousands of studies of different quality, in different populations to judge an answer with uncertain outcomes. When I acted as an expert reviewer for the IPCC there were nearly 2000 PhDs reviewing the draft and over 10,000 comments. Language models do not do evidnence synthesis like this or a systematic review like Cochrane reviews.

The synthesis in science also requires understanding what wasn’t published. Stroke research is the cautionary tale. Back in 2006, labs around the world had tested 1,026 drugs to protect the brain after a stroke and most looked promising in animals10. Many were tried in patients but almost none helped11. Why?

Part of the problem was what we call in science positive publication bias. In 2010, a study synthesized the published research on more than 500 animal stroke studies and found only 2 percent reported that a drug did nothing. In other words, 98% of the published literature on this topic was positive for the drug. They estimated that leaving out the unpublished experiments made the treatments look about a third better than they were. It’s like judging a gambler only on the bets he won12.

There is also a huge knowledge universe that never gets written down or is hiding from the published literature. A predecessor compound that failed, an effect that has never replicated outside one lab or the author who overstates the data. That knowledge is available to AI, it lives in lab meetings, conference corridors and the excel spreadsheets across tens of million of scientists.

AI can train on every word science has published. It can’t weigh the experiments and evidence that were never published - only experts have that knowledge.

More compute, more parameters won’t close that gap, because the gap isn’t in the model; it’s in the data. A system trained on the written record cannot be superintelligent about questions whose answers sit outside it. In chess, a confidently wrong answer loses a game. With a father’s cancer or a child’s treatment, it misinforms the people who can least afford it.

How to scrutinise AI to be more scientific?

The foundations for this newsletter haven’t changed - sourcing verified facts in health and science. However the tools to do that have changed since Metafact, so I’m renaming it Scrutinised.

For future posts I’ll show more ways AI can mislead us on our health questions, with examples. Then I’ll turn to trying to fix it, by sharing what I’ve been building to make AI more scientific in answering our questions, with researchers in the field checking along the way.

If you do have any health questions you would like to get scrutinised - share them along with the AI answer and I will share how some of the answers stack up against the evidence.

May the facts be with you!

Thanks for reading

Ben

I hope you are safe and well. As supporters and subscribers of Metafact, I wanted to share with you some exciting news that today Metafact has come into an agreement to become part of Consensus!

When we launched Metafact more than 5 years ago, we set out to help people fight misinformation by building a new type of knowledge engine. One that openly allows anyone to check facts from a verified consensus of experts on any topic.

We were 100% member funded and I’m very proud of what we were able to achieve including openly publishing nearly 4000 expert answers online covering hundreds of topics, writing hundreds of consensus articles and topic reviews within this newsletter.

Misinformation is now at an even larger scale than when we started. ChatGPT and AI are changing the internet - which is both exciting and frightening. 

It’s exciting since we can ask questions and get answers back in normal human language. 

It’s frightening since ChatGPT, Google and Microsoft all train their language models from the entire internet, which is full of misinformation. They are also prone to ‘hallucinate’, making things up entirely. Misinformation is therefore being scaled exponentially by technology.

Consensus is very different as it allows anyone to ask the entire 200 million strong peer-reviewed research database questions - giving us all more trusted answers. I'm thrilled about its potential to help everyone.

What is Consensus?

Last year Eric and Christian, the founders of Consensus, reached out to me and we started discussing ways ‘to make expert knowledge accessible and consumable for all’, which is the Consensus mission. They shared how they have built a more scalable expert answer engine.

Instead of jamming the entire internet into a model and hoping it spits out factual content, they started with the best source of expert knowledge on the planet - peer-reviewed scientific literature - and built a search engine with AI models “around it”. They use AI to pull out answers and synthesize insights across papers, but because it is a search engine first, every single insight is grounded in an actual scientific study.

Consensus was born - and I have become very excited in what the future holds for building a more trusted scalable knowledge engine. I know Eric and Christian are passionate about democratizing expert knowledge - so joining Consensus was a perfect fit.

Extracting knowledge from scientific research was a huge pain. Asking simple questions like ‘Is climate change caused by humans?’ wasn’t previously possible. Metafact solved this by asking real experts to provide an answer in language anyone could understand.

What Consensus does is give you the ability to ask the entire 200 million strong peer-reviewed database questions - where it finds the best research articles and synthesizes them into a nicely written 'Consensus’. I love it as it uses the consensus concept we introduced at Metafact and makes it scalable within the research literature.

What does this mean?

The Consensus engine super-charges the amount of verified expert knowledge available to write articles and reviews. So this newsletter will continue and grow - which I will share when those details emerge.

To all our paid subscribers and members, you’re Metafact paid membership will now transfer across giving you access to the Consensus Premium tier! Eric from Consensus will follow up on those details soon.

All of the content on the Metafact website will remain open and freely accessible via both the Metafact website and the Consensus platform. In the future, it will likely be added to the Consensus engine, helping distribute this expert content to an even wider audience.

For me, I continue to remain passionate about helping build the most trusted expert knowledge engine so everyone can make the best decisions in their life and for the world around them. So I am super excited to help Consensus do that.

Thank you

I want to sincerely thank all our members and supporters - we couldn’t have done anything without you.

May the facts be with you!

Ben

To celebrate the partnership, Consensus are offering all free Metafact newsletter subscribers 25% off Consensus Premium forever! Visit this page: https://consensus.app/pricing

• Click your desired plan (monthly or yearly)

• On the checkout page, enter this code where it says "promotion code": Metafact25
  

Artificial Intelligence has seen a surge in popular interest ever since ChatGPT made it easier for people to ask the internet questions. Our understanding of Human Intelligence seems to have taken a back-seat in recent times. So we gathered more than 30 of the worlds top researchers in neuroscience, education and intelligence to share the facts about Human Intelligence. From IQ tests, Nature vs Nurture to brain games and even whether liberals are more intelligent, this review created lots of debate amongst experts and subscribers when we published it. Here’s what we found…

Takeaways

1. Genes play a big role in determining your intelligence - from 50-80% in the later part of life.

2. But genes aren't determinative. Education and environment is still critical for children.

3. IQ tests are one way to measure intelligence. In general, they're fairly accurate at predicting certain outcomes like grades and general success in life.

4. Brain games don't boost your intelligence. 

5. Creativity declines from middle age(~44). But your general knowledge and vocabulary will likely increase over your life.

6. Emotional intelligence is important. Difficult to test for but certain people are better at reading others' emotions.

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INTRODUCTION

Is intelligence nature or nurture?

In 2014, the famous podcaster Joe Rogan posted a YouTube video in which he discussed his experience taking a “brain supplement” called Alpha BRAIN. “My ability to form sentences seemed smoother,” he claimed. “It seemed like I had an extra gear, like I was one step ahead in conversations … It’s 100% legit.”

But is it 100% legit? Fire up a YouTube channel or a podcast, and it’s not uncommon to hear all sorts of host-read advertisements for brain pills that promise to boost performance and increase intelligence. Peruse your smartphone’s app store, and you’ll find any number of apps claiming they will train your brain to be smarter. It’s not until you read the small print on many of these products that you’ll find some disclaimer that they haven’t been tested or approved by any regulatory bodies.

Humans are fascinated by intelligence. We venerate the geniuses in our society while attaching pejorative terms -- moron, idiot, nincompoop -- to those we perceive as less intelligent. Most of all, we’re obsessed with becoming smarter and more knowledgeable.

Is it possible to increase your intelligence? How much is it determined by genetics? Does it decline with age? And what about the more nebulous concept of “emotional intelligence”? Does it really exist?

Those are just some of the questions we’re answering in this month’s Metafact Review. Buckle in, aspiring Einstein, it’s time to consult the experts.

NUMBERS

Meta-Index

98: Average IQ score in USA

102: Average IQ for college undergraduates

160: Estimated IQ score of Albert Einstein

73: IQ falsely reported for Donald Trump

26%: Of American adults take at least one supplement for brain health

$8,600,000,000: Amount spent globally on brain health supplements in 2022

1905: First intelligence test developed called the Binet-Simon Scale

3.13 sec: Amount of time taken to solve a Rubick’s cube by world record holder

25: Age at which the brain is said to be fully developed

1964: Year the term “emotional intelligence” was first used in a paper

ORIGIN STORY

Where does intelligence come from?

Humans have attempted to gauge each other’s intelligence going back hundreds of years. One of the first people to research intelligence was Englishman Sir Francis Galton in the 1800s. He set up a lab to measure noblemen's physical characteristics, testing their reaction-time and other sensory attributes. Galton pioneered quantitative approaches to measure intelligence and coined the phrase 'Nature vs Nurture' in 1874 - a topic that continues to spark immense debate today.

Charles Spearman, an English psychologist noticed that students grades were similar across a range of diverse subjects. In 1904 he proposed the concept of 'General Intelligence' in which each of us have a single underlining 'factor' (g) for mental and cognitive abilities that could be measured.

Meanwhile William Stern, a German psychologist, came up with the idea of taking someone’s intelligence and comparing it to the average intelligence of people of the same age. He called this the “intelligence quotient,” i.e., IQ.

At around this same time, psychologists Alfred Binet and Théodore Simon were developing intelligence tests for children. By the 1920s, these tests had become standardized, and soon IQ tests were considered a reliable way to measure a person’s intelligence.

But even from the very beginning, psychologists considered IQ tests to be heavily flawed. That included Stern, the very person who coined the term. “Under all conditions, human beings are and remain the centers of their own psychological life and their own worth,” he wrote in 1933. “In other words, they remain persons, even when they are studied and treated from an external perspective with respect to others’ goals.”

In 1987, psychologist Raymond Cattell published a book that challenge the prevailing idea there was an underlining single factor defining general intelligence. His suggested intelligence to be split into between structured learning and creative learning, sometimes known as Crystallised Intelligence and Fluid Intelligence.

Fluid Intelligence is the ability to use reasoning to solve new problems without reference to pre-existing knowledge. Crystallized Intelligence is the ability to use knowledge previously acquired through education and experience. Metafact experts refer to these terms often - so it's important to understand what they mean..

CONSENSUS

Are IQ scores a good predictor of general intelligence?

100% Affirmative via 7 experts

Ever since the IQ test was invented, people have debated how good it is at actually determining a person’s intelligence. Critics have pointed out that a person’s socioeconomic status and other environmental factors can strongly influence their IQ score, leaving one to wonder whether it truly measures innate intelligence.

Metafact experts largely agree that IQ is a good predictor of general intelligence, but with plenty of caveats. “The real problem is that general intelligence as it has traditionally been defined is not so general,” wrote Robert Sternberg, and expert from Cornell University. “It does not take into account creative intelligence, practical intelligence (common sense), emotional intelligence, social intelligence, or wise uses of intelligence.” Sternberg went on to criticize our overreliance on standardized testing as a proxy of potential, arguing that “these tests do NOT measure our skills in solving important life problems.”

Whether you think IQ scores predicts intelligence will rely largely on what you think qualifies as “intelligence.” “It is reasonable to expect that more intelligent individuals will obtain more education, achieve better grades, have higher incomes, be healthier, happier, attain higher social status, be less likely to develop a drug addiction, and be generally more effective in their chosen occupations,” wrote Louis Matzel, and expert from Rutgers University. “So the question is, does an IQ test that is administered to a young child predict these later life outcomes that we believe are indicative of intelligence. The answer to this question is an overwhelming ‘yes.’ IQ tests have enormous predictive capacity.”

CONSENSUS

Is intelligence genetic?

100% Affirmative via 5 experts

As mentioned, it’s been shown that environmental factors do play a role in determining a person’s IQ. And yet we also widely perceive intelligence as something a person is born with. So what role do genes play in determining a person’s intelligence, and how much is it affected by outside, real-world factors like family income, education, and family upbringing?

Metafact experts unanimously agree that intelligence is heavily influenced by genetics and hereditary, but only to a certain extent. “There is a tremendous amount of empirical research clearly showing that intelligence is hereditary,” wrote Dimitri van der Linden, and expert from Erasmus University Rotterdam. “The estimates range somewhere between .50 to .80 (and are likely closer towards the latter).” He and others pointed to twin and adoption studies, the latter showing that parents’ are more likely to have similar IQs to their biological children compared to children they’ve adopted.

Genetic influence on intelligence actually increases with age. “Children adopted at very young ages resemble their adoptive parents in terms of IQ test scores when they are children (i.e., age 5 and younger)" wrote psychologist Nicholas Grahame from Indiana University. "As they grow older, though, they increasingly resemble their biological parents. By the time these children are 16 or so, about 70 to 80% of the differences among individuals can be chalked up to their biological parents' genes, rather than the environment in which they were raised”.

Despite the importance of genes, "they aren't determinative" writes Louis Matzel from Rutgers University, as they "interact with the environment to determine the ultimate level of expression".

Small genetic dispositions can be switched on or off in diverse nurturing environments. "This is why estimates of the heritability of intelligence (as might be obtained from studies of twins) are higher in diverse environments where vast cognitive opportunities exist, and are lower in restricted environments where individuals can’t select cognitive challenges that are appropriate for their abilities. Thus while intelligence is highly heritable, the pure role of genes (absent appropriate environments and opportunities) is probably much lower than these estimates would suggest" Dr Matzel writes.

Vittorio Daniele, an expert from University Magna Graecia, also points out the interplay between genes and environment aren’t mutually exclusive, since “genes expression depends on environment. It is recognised, for example, that extreme poverty and deprivation in infancy negatively impact on individuals’ cognitive abilities."

Is intelligence fixed?

So if intelligence is subject to environmental factors, does that mean there are actually ways to alter it? Scour YouTube and the dietary supplement aisles of your local pharmacy and you’ll find all sorts of products and exercises that will supposedly “boost” your brain activity and IQ. But can the average person take steps to actually improve their own intelligence?

“Intelligence is definitely not fixed,” wrote Andreas Demetriou, an expert University of Nicosia. “In the general population, intelligence increased by about 3 IQ points every in every decade over the 20th century (the phenomenon known as the Flynn effect). Also, intelligence increases by about 2-4 IQ points for every additional school year.” The reason for this is that the brain, itself, is very flexible. “The brain is neuroplastic and keeps changing,” argued Gavin Brown, an expert from University of Auckland. “Stimulus from environments which requires flexibility in processing and exploitation of schematised structures keeps the brain active forming new paths.”

That being said, training exercises focused on boosting intelligence haven’t produced many longterm benefits, at least in controlled studies. “Under some controlled laboratory conditions, various types of cognitive training can have beneficial effects on IQ, but even in these cases, the effects are small (and sometimes non-existent) and always appear to dissipate upon completion of training,” wrote Louis Matzel, an expert from Rutgers University. Davide Piffer pointed to several meta analysis showing that intelligence training doesn’t work. “It's possible to boost only specific cognitive abilities that are similar to the trained task, via near-transfer effects.”

Of course, the biggest boost to intelligence often comes from formal education, which could be considered a form of training. “Studies have been shown that more schooling is causally related to increases in intelligence,” wrote Robert Sternberg, an expert from Cornell University. “This makes sense, as schools--at least, reasonably good ones--exercise one's mind and one's brain.”

CONSENSUS

Is there a correlation between grades and intelligence?

100% Affirmative via 5 experts

Given the role education can play in boosting intelligence, does that mean grades are a good indicator of intelligence?

To a certain extent, yes. “The 2007 paper by Deary et al examining the relationship between academic grades and measured intelligence among a sample of 70,000 Scottish secondary students reported a strong correlation of 0.81,” wrote Michael O'Connell, an expert from University College Dublin. “So overall, there is consistent evidence of a moderate to strong correlation between academic grades and measured intelligence.”

That’s not to say there aren’t caveats and exceptions. “Culture, learning disabilities, and even gender may play a major role in predicting academic grades in various settings on one hand,” wrote Leehu Zysberg, an expert from Gordon College. “While on the other - intelligence measures are deeply biased by the very same factors.”

Other Metafact experts were more skeptical of the relationship between grades and intelligence. “The relation between the intelligence and grades is only probabilistic and it depends on many other influences, like social status, income, race, and stereotypes,” wrote Hynek Cígler, an expert from Masaryk University. “If you cannot spend a lot of time studying, or if the study is not valued in your family, you obviously wouldn't have good grades. On the other hand, grades are also dependent on many other traits, like your motivation, conscientiousness etc. Even if you are not really smart, with a huge motivation you can learn a lot and be ‘excellent student.’” Gavin Brown from University of Auckland put it in even simpler terms: smart kids do dumb things (e.g., drugs, not attend, don't try, etc.).”

CONSENSUS

Do brain games work?

100% Negative via 3 experts

Fire up your smartphone’s app store and you’ll find any number of “brain training” games that claim to make you smarter. But there is any scientific evidence that they actually work?

Not really. “Meta analytic reviews of the empirical literature indicate either tiny or absent gains,” wrote Nachshon Meiran, an expert from Ben-Gurion University of the Negev. “In my opinion, given what we know, it is unfair (or worse) to promise otherwise.”

To a certain extent, these games do train your brain, but this doesn’t mean they make you smarter in any sense of the word. On the whole ... we find that these games only improve the task you are training on, they don't yield general benefits,” wrote Michael Thomas, an expert from Birkbeck, University of London.

The same can be said for these games’ ability to stave off dementia in old age. “I find dementia severity and dementia risk to be specifically related to ‘delta,’ an aspect of general intelligence (‘g’),” wrote Donald R Royall, an expert from University of Texas Health Science Center at San Antonio. “Domain-specific cognitive performance is ‘orthogonal’ (unrelated) to g and delta. While training may improve domain-specific cognitive performance, it is unlikely to be having effects on intelligence unless it generalizes to ALL cognitive domains (and may even other brain-related functions). We're far short of that.”

CONSENSUS

Does IQ decrease with age?

40% Uncertain via 5 experts

There are a lot of fears associated with getting older, chief among them is cognitive decline. Any person who’s had a grandparent suffering from dementia how their own cognitive abilities will fare as they age. Is it a rule of nature that intelligence will decline as you age?

Our Metafact experts were torn on this subject. Partly this had to do with the fact that it’s hard to create a controlled, apples-to-apples comparison between age group IQs. For example, younger people today are much more likely to go to college, which has been shown to boost IQ, so you can’t just compare the intelligence of a group of 30-year-olds to a group of 70-year-olds. Alan S. Kaufman, an expert from Yale University, conducted experiments that controlled for these factors, and he found declines in crystallized intelligence and fluid intelligence. Here are his findings:

Average crystalized intelligence per age group:
Ages 20-24: 98 IQ

Ages 35-44: 101 IQ

Ages 45-54: 100 IQ

Ages 55-64: 98 IQ

Ages 65-69: 96 IQ

Ages 70-74: 93 IQ

Ages 75+: 88 IQ

The drop is even more precipitous for average fluid intelligence:
Ages 20-24: 100 IQ

Ages 25-34: 99 IQ

Ages 35-44: 96

Ages 45-54: 91 IQ

Ages 55-64: 86 IQ

Ages 65-69: 83 IQ

Ages 70-74: 79 IQ

Ages 75+: 72 IQ

Other experts argue that aging alone isn’t what causes intelligence decline. “An important characteristic of genetics and early life factors is that they don't tend to change as we age,” wrote Ian Silver, an expert from University of Cincinnati. “As such, if approximately 77-79 percent of intelligence is influenced by factors that don't change as we age, it is unlikely for our level of intelligence to decrease as we age. Negative environmental stimuli (e.g., head trauma) and serious diseases, however, can result in declines in general intelligence. The influence of these factors can correlate with age but aging alone does not influence intelligence.”

Michael Thomas, an expert from Birkbeck, University of London, argued that there are tradeoffs to getting older, with some forms of intelligence improving while others decline. “The fastest response times you will ever have are in your mid-twenties, but (so long as you don't develop dementia), your knowledge of vocabulary will increase throughout your life. Into your late sixties, most cognitive skills relying on things you have learned (so-called crystalised knowledge) either increase or are pretty resilient. The speed with which you can do things can decline.”

CONSENSUS

Is there scientific evidence for emotional intelligence?

92% Affirmative via 13 experts

While general intelligence is well-understood, some psychologists have argued for the existence of “emotional intelligence.” One online dictionary defines it as “the capacity to be aware of, control, and express one's emotions, and to handle interpersonal relationships judiciously and empathetically.” In other words, how good are you at reading others’ emotions and moderating your own emotions accordingly to get a desired response?

Metafact experts were mostly in agreement that emotional intelligence exists, though still in need of further study. “Emotional intelligence is hard to measure,” wrote Andrew M Lane, an expert from University of Wolverhampton. “Can people report on their inner knowledge? if you have poor emotional intelligence, you won’t know how good you are but might recognize that being good in emotional intelligence is desirable - because questionnaires are relatively easy to guess what is being assessed.”

Some scientists have attempted to study whether higher emotional intelligence results in any measurable impacts to quality of life. “My research ... found that increased Emotional Intelligence (EI) has a beneficial effect in terms of current depression status,” wrote Sandra J Lloyd, an expert from Northcentral University. “The study indicated that for every 1-point increased in the EQ scaled score, the risk of depression decreased by 5%. This is a highly significant result, as this provides clear evidence that; emotional intelligence and depression are strongly related in the older adult population.”

A crucial flaw with many of these studies, however, is that they rely too heavily on subjective data. “A huge amount of research just used self-report questionnaires and correlated them to other attributes (like depression, life success etc.), but it did not focus on the nature of E.I,” wrote Hynek Cígler, an expert from Masaryk University.

Quick Answers

Is it possible to boost your intelligence by training? Education - yes. Brain games - no.

Is intelligence negatively correlated with religious belief? Seems so- but that doesn't imply causation.

Are smart people more liberal? Apparently.

Does music make kids smarter? Smarter kids tend to take music lessons but the evidence for the other causal direction is extremely weak.

Are IQ levels in decline? Maybe.

TOP ANSWER

On average, do men and women differ cognitively?

Unlikely writes Michael Thomas, a neuroscientist from Birbeck, University of London:

Boys and girls don't differ on mathematics skills. Yet these days it is widely recognised that women have much lower representation in Science Technology Engineering and Maths (STEM) occupations. This tells us cultural differences are at work. Any two groups of adults are going to differ if they have different levels of training on some activity. But the differences in cognitive abilities between the genders in children are very small, and when found, they are often not replicated in other studies.

One scientist analysed data from around seven million people looking at gender differences across a range of activities from talking to throwing (Shibley-Hyde, 2005). She found that over three quarters of the studies showed gender differences to be small or almost absent. Even where small differences are found, the much more salient pattern is of great overlap between the distributions of performance. That is, any individual boy will probably do better than lots of girls, and any individual girl will probably do better than lots of boys.

So while there may be some differences between how girls and boys think, those differences are smaller than once thought – and much smaller than the amount of overlap between boys and girls.

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Is Organic Food Worth it?

A trip to the grocery store is overwhelming for the best of us. Thousands of food products competing to get your attention in a limited time. 'Organic' has become one of those labels that help differentiate food products from the crowd. We tend to associate natural, healthy perceptions with the 'organic' label and judging by consumer trends, it's working.

Today, about four in ten Americans eat some sort of organic food regularly while some 15% of all fruit & vegetables sold today in the United States is ‘Organic' - a proportion that has doubled in ten years.

Organic produce is more expensive but many of us don't mind paying a premium for an 'organic' apple, if you get significant health & environmental benefits in return. Polling suggests 75% of organic food consumers believe it's healthier than conventional food. Is this perception true? Is organic food healthier? Better for the environment? Is the price premium worth it?

We asked independent global experts in organic agriculture, plant biology and food chemistry to share the facts about Organic Food. From the evidence on whether organic foods is healthier, to whether they are safer and better for the environment, our subscribers found this review to be one of the most surprising over the past few years. Here’s what we found…

Takeaways from Experts

1. Both organic and conventional pesticide residues on foods are very safe

2. Organic food is not ‘pesticide-free’ and you should be wary as many natural products used don’t have safe oversight

3. Organic food has not been proven to lead to measurable health benefits

4. No evidence that organic food tastes better, other than the perception via labelling

5. It's highly unlikely that Organic farming could feed the world on current consumption patterns

6. There is no clear health or environmental benefit from switching to organic food. In fact, for climate change, organic food is likely worse

NUMBERS

Meta-Index

$200,000,000,000: Global sales of organic food in 2022

76,400,000: hectares of organic farmland globally

35,700,000: hectares of organic farmland In Australia alone

1.6%: Proportion of farmland categorized as ‘Organic’

8.8%: Proportion of organic farmland in Australia

14.6%: Organic fruit & vegetable sold in US, as a proportion of total market

75%: Proportion of people who purchased organic food who believe its better for one’s health than other produce

54%: Americans aged 18-29 say a product labeled organic would be more appealing

ORIGIN STORY

DDT and the alternative farming movement

In 1943, English botanist Sir Albert Howard took his own practical learnings on farms in India to write “An Agricultural Testament”.  The book lays out the core principles of an alternative 'organic' farming system that relies on utilising and recycling available waste material to maintain healthy soil and nutrient content for plant growth.

In the 1960s, the post-war boom was in full swing. The growing population meant the need to produce more food, lots of it. To do that, farmers were encouraged to buy more land, more machines, more fertilizer, and more pesticides to produce everything they could from each square mile of land.

Meanwhile, the alternative organic farming movement was stagnant. But in 1962, the Silent Spring was published, a seminal book by Conservationist Rachel Carson on the environmental impact of pesticides like DDT. Although DDT was subsequently banned in the 1970s, the organic farming movement was galvanised. By 1973, Oregon state passed laws regulating ‘Organic’ farming  to only allow use of pesticides and fertilizers of ‘organic origin’. States and countries followed and farmers all around the world now need accreditation to be awarded the coveted 'organic' seal. 

KEY QUESTION

Are pesticide residues on fruit & vegetables harmful?

The effect of toxic pesticides like DDT played an important and justifiable role in creating the organic farming movement.  With governments stepping in to ban DDT and other pesticides,  what about today? With the use of hundreds of synthetic pesticides approved for use in conventional farms, are we being exposed to harmful levels of pesticides in conventionally grown foods?

“Extremely Unlikely” says Dr Dirk Lachenmeier, food chemist and toxicologist in Germany. “Conventional fruits & vegetables are not harmful if they comply with the limits that are considered as being safe using risk assessments, e.g. from EFSA and other bodies. Our monitoring shows that limits are very rarely exceeded and even then, there are safety factors (typically 100) between the food limit and health effects to offer a wide margin of consumer protection” he writes.

Yet it’s important to recognise that natural 'organic' chemicals can be equal or even more toxic than conventional synthetic chemicals.  “Organic consumers may be exposed to organic pesticides such as Copper sulfate, the insecticide Spinosad or some antibiotics such as streptinomycin” says Professor JM Mulet, a plant biologist from Spain. What's important is that both conventional and organic pesticide residue levels are not harmful, as “the levels of pesticides in the food of western countries is several orders of magnitude below the recommended levels” he says.

CONSENSUS

Does organic farming use pesticides?

100% Affirmative via 3 experts

Pesticides are used to protect crops against insects, weeds, fungi and other pests. Most people tend to believe that organic produce is pesticide-free, or even ‘chemical-free’. That is entirely false according to the experts we asked.

In the United States, the Organic Materials Research Institute (OMRI) is the place to register a chemical or pesticide for organic use. Dr Linda Chalker-Scott, a horticulturist from Washington State University shares the current list of chemicals and products here. “It’s a long list.. Many of these products have no tested efficacy; many of those that have been tested are worthless; and many are more dangerous than synthetic [pesticides]. They just happen to be naturally occurring and therefore registered for organic use” she writes noting many listed are ‘snake oil products’.

Although experts agree that pesticide residues will be lower from organic food than conventional foods, just because something is natural does not make it environmentally better or safer than the synthetic pesticides. “For example, copper salts are used as fungicides in organic farming” writes Professor Michael Palmgren, a plant biologist from the University of Copenhagen. “Copper is a heavy metal that does not disappear from soils when introduced and in the long term it drastically affects soil microbes and worms. This is not good for the environment and therefore organic farming is not always sustainable, which is a problem”.

"This is also true also when talking about fertilizers: nitrogen (in the form of ammonium and nitrate) in manure (allowed in organic farming) and synthetic fertilizers (not allowed) are chemically identical….Application of excess nitrogen in the form of manure might lead to unsustainable pollution and, depending on the way it is administered, may pollute more than synthetic fertilizers” he writes.

CONSENSUS

Is organic food healthier?

50% Uncertain via 6 experts

Most Americans (~55%) believe organic produce is better for one’s health than conventionally grown produce. Is there science to back this up? Is an ‘organic’ tomato healthier?

Some differences in the composition of foods have been observed. “Organic fruits and vegetables have been shown to have antioxidant concentrations about 25% higher than fruits and vegetables that are conventionally grown” writes Dr Cynthia Curl from Boise State University. But this does not automatically imply better health writes plant biologist Professor Michael Palmgen from the University of Copenhagen. In fact, organic food may create 'toxic secondary metabolites' as the plant tries to defend itself under organic conditions.

Organic milk usually does have a slightly higher amount of the healthy Omega 3 fatty acids writes Professor Ian Givens from Reading University, although ‘the changes are too small to have an effect [on health]’ he says. Organic milk he notes, has a health risk for certain people as it's lower in key nutrients like iodine which is 'a concern for pregnant women’ and those with marginal/sub-optimal iodine status.

Some studies have shown that organic food consumers are healthier than conventional food consumers. "But these results are explained because organic food consumers are usually more health-concerned that conventional food consumers and have better diets, or are mainly vegetarian, which lowers the risk of obesity and type II diabetes", writes Professor JM Mulet.

“While some data suggest that organic food may, in some ways, be considered more "nutritious"....these differences in nutritional content have not been shown to be directly associated with any measures of improved health” writes Dr Cynthia Curl. “It is difficult to draw a firm conclusion as to whether these differences are sufficient to result in any clinically-relevant health benefits. One can achieve a healthy diet rich in antioxidants and low in omega-6 fatty acids from either conventional or organic sources”.

Although it seems there is little evidence to support organic food is healthier than conventional food - horticulturalist Dr Chalker-Scott writes that greenhouse-grown foods are 'less nutritious' than those grown outdoors. Plants grown outdoors receive the full light spectrum from the sun, triggering 'numerous plant products with perceived or actual health benefits'. So for optimal health, best to choose outdoor grown fruits & vegetables.

KEY QUESTION

Does Organic Food taste better?

Half of Americans who purchased organic food say it tastes better. Is there science behind this?

Dr Roberto Lo Scalzo is a food chemist at the Council for Agricultural Research in Italy. He published a study in Food Chemistry, that investigated whether Italian tomatoes tasted better from organic crops. The only difference they found was that organic tomatoes had ‘slightly more sugar and acidity’ than conventional tomatoes. Citing previous work, Dr Lo Scalzo writes “the global claim that organic food tastes better is not valid”.

Although there is no scientific evidence for organic food to have better flavor, there is alot of psychological evidence showing that we perceive goods to taste better when paying more for them. In 2013, Swedish researchers designed a study to test whether consumers perceive organic to taste better. They gave 44 people two cups of arabica brewed coffee. One labeled ‘Organic/Eco-Friendly’ and the other no label. Unbeknownst to the participants, the two cups contained coffee from the exact same brew and brand. Yet the researchers found a taste preference towards the eco-friendly labelled coffee - even though they were exactly the same as the non-labelled version.

“Taste is in the tongue of the beholder: people will be convinced that organic food tastes better because they believe it does” writes Dr Chalker-Scott from Washington State University. “The taste differences that are most dramatic are those between greenhouse grown produce and outdoors produce. The latter have better flavor regardless if they are conventional or organic” she says.

CONSENSUS

Is Organic Food safe to eat?

60% Negative via 5 experts

As the levels of pesticide residue on conventional food is very safe (see above), is there a health benefit from consuming organic food? "Consumption of an organic diet significantly lowers exposure to several classes of synthetic pesticides...However, available evidence is insufficient to determine whether these reductions are associated with improved health" writes Dr Cynthia Curl from Boise State University.

Pesticide use does however pose a real danger to farm workers. "In the US alone, an estimated 10,000 - 20,000 farm workers are acutely poisoned by synthetic pesticides each year, and organic food production clearly reduces the use of these synthetic pesticides and thus the opportunities for these adverse events" writes Dr Curl. Other experts note the dangers are still present in organic farms as "some organic farmers use highly toxic pesticides such as sulfur that can cause environmental harm and negatively affect worker health" writes Dr David Crowder from Washington State University.

Organic farming relies on manure (animal faeces) instead of nitrogen fertilizers for conventional farming. So organic farming can increase the risk of food contamination by enteric pathogenic microorganisms (E. coli, Salmonella and Listeria) and consequently pose health risks. But evidence for wide-spread contamination from organic food is uncertain based on a recent review. However experts were clear on the risks posed by organic food.

"There have been many food security concerns related to organic food, like the E. coli outbreak in France and Germany in 2011, due to the fact that organic farming uses manure, whose pathogenic microbiological content is more difficult to control than for synthetic fertilizers" writes Professor JM Mulet from Spain.

"Organic food is not at all safer" writes Dr Linda Chalker-Scott from Washington State University. "Witness the numerous cases of food poisoning from organic restaurants or from organic produce. Food safety practices are important regardless if the food is organically or conventionally grown" she says.

CONSENSUS

Is Organic Food better for the environment?

50% Uncertain via 8 experts

Of all the claimed benefits of organic food, we assumed that organic food would have clear environmental benefits. In fact, we were wrong. On a global scale, organic food would have a serious negative impact on the environment. It's a complex issue, so here's what we know.

A recent major review suggests organic farming uses less energy, emits comparable greenhouse gas emissions, but has higher land use and greater nutrient pollution of waterways compared to conventional farms. Organic farming is likely to have other local environmental benefits including better soil quality, lower pesticide residues and local bio-diversity.

Although current evidence suggests organic fertilizers seem to pollute nearby waterways more than conventional farms, experts worry the most about land clearing as organic farming expands. Organic farming is ~20% less productive than conventional farming methods so "one would need a larger area for farming than is used currently" writes Professor Michael Palmgren from University of Copenhagen. "If that implies that we will have to cultivate more of the nature that we have left, that would certainly not be good for the environment" he says. If expanding organic farming leads to greater land use this would lead to ‘habitat fragmentation’ notes Professor Guy Kirk from Cranfield University, lowering biodiversity around the world.

So it mostly comes down to whether organic farming can expand without increasing the existing land footprint of agriculture. “Yes", switching to the world to organic would benefit the environment, writes Dr Adrian Muller from Research Institute of Organic Agriculture in Switzerland "if a large increase in area used can be avoided".

Is Organic food better for climate change?

What would happen to greenhouse gas emissions if agricultural production in England & Wales switched to 100% organic farming? Professor Guy Kirk from Cranfield University recently published a study answering this, showing that in fact, carbon emissions would increase by about 21% in comparison to existing conventional farming methods.

We asked Professor Kirk if switching to organic farming would cut greenhouse emissions. “No” he writes, “there are undoubted local environmental benefits...bu this needs to be set against the requirement for greater production elsewhere” which leads to more land use carbon emissions. Since organic farming is less productive, it would mean that more imports would be required to maintain food supplies in England. By converting natural or semi-natural land to farms overseas would result in substantial increases in carbon emissions and sequestration from soils.

CONSENSUS

Could Organic Food feed the world?

50% Uncertain via 8 experts

As the world moves towards a population of 10billion in the middle of this century, a key question is whether organic farming methods could supply enough food. “The estimates of the carrying capacity of Organic Agriculture are 3–4 billion" writes Professor David Connor from the University of Melbourne, "Clearly well below the current world population or that anticipated in 2050 (9.8 billion)”. 

“Due to considerably lower average crop yields” writes Professor Kenneth Cassman from University of Nebraska, “if there was a massive expansion of [organic] crop production area, it might be possible. But expansion of [organic] production area would have massive negative environmental impacts”.

Other experts disagree. "Organic farming could feed a world of 7.8 billion (current numbers)" writes Professor Jules Pretty from the University of Essex. Professor Pretty cites better organic yields in developing countries while pointing out changes to dietary choices and consumption patterns in the West will be needed. For example, nearly one-third of food produced today is lost or wasted writes Dr Adrian Muller from the Research Institute of Organic Agriculture in Switzerland.

Prof Nick Hewitt from Lancaster University writes how inefficient our dependence on meat for food is. Meat production for example, gives the world 18% of global calories yet “relies on feeding 34% of human-edible crop calories to animals globally”.

To go anywhere near feeding the world via organic farming, it seems a big change in lifestyle would be needed, at least in wealthy countries. “Without any changes in our lifestyles, the organically grown produce might not be sufficient to feed the world without bringing more land (that is: nature) under the plough" writes Professor Michael Palmgren, plant biologist from Denmark. "However, if we eat the produce directly instead of feeding it first to animals, and thereby reduce waste, there will certainly be enough to feed the world”. Whether such food waste and meat consumption patterns are likely to change remains a big question.

Quick Answers

Why is Organic Food more expensive? Organic production methods are less efficient than conventional methods, so a loss in production must be compensated with a higher price.

Are pesticide residues on fruit and vegetables harmful to health? In Europe, USA and other advanced economies - No.

Does organic farming use less water? Uncertain

Will eating organic food significantly lower pesticide residue exposure? For synthetic pesticides - Yes.

Are organic wines healthier? - No, alcohol content is the same.

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In 2019 we gathered more than 50 of the worlds top researchers in neuroscience to share the facts about Alzheimer’s Disease. We’ve updated this review with the help of Professor George Perry, one of the world’s top experts in Alzheimer’s Disease from the University of Texas, San Antonio.

From diet and genetics to that long-held claim on cooking with aluminium, here’s what we found…

INTRODUCTION

Why Alzheimer's?

Imagine cleaning your kitchen and you place a frying pan in the refrigerator. This happened to Fiona, the lead character in the 2006 film “Away From Her”. In isolation, it would be an absent-minded mistake. In the film, it's an ominous revelation: Fiona has early-onset Alzheimer’s. That means she will lose her memories and sense of self. Fiona is not alone, she depicts what millions of people around the world suffer every day with Alzheimer's Disease.

Alzheimer's is a neurodegenerative disease that results in gradual cognitive decline. What starts out as simple memory loss often leads to confusion, paranoia, and the inability to carry on a conversation or even form words.

In the U.S. alone, it’s estimated that over 6 million people suffer from Alzheimer’s. Despite its pervasiveness, scientists don’t seem close to a cure. While we’ve gained a better understanding of how Alzheimer’s affects the brain -- the buildup of something called amyloid plaques -- effective treatment for slowing or preventing Alzheimer’s are elusive. And recent research suggests that removing the plaques is not a panacea to a cure.

This has left many wondering about the causes of Alzheimer’s -- whether they’re genetic or environmental -- and what people can do, if anything, to decrease their chances of developing the disease. We at Metafact are here to answer those questions.

NUMBERS

Meta-Index

50,000,000: Number of people world-wide with dementia

70%: Proportion of those with dementia having Alzheimer’s Disease

3: Seconds for someone in the world to be diagnosed with dementia

$1,789,000,000: US National Institutes of Health research spending in 2018 on Alzheimer’s Disease

0.8%: Proportion of US research budget spent on Alzheimer’s Disease

147,214: Number of research papers published relating to Alzheimer’s Disease

134,602: US deaths in 2015 associated with Alzheimer’s Disease

100: Number of anti-Alzheimer's drugs that have failed in recent decades

ORIGIN STORY

Dr Alois Alzheimer

In 1906, Dr. Alois Alzheimer discovered never-before-seen changes in the brain tissue of Auguste Deter, a 55-year old woman who had recently died. For years Auguste had been suffering from an unknown mental condition involving significant memory declines, speaking and language problems, and bizarre, erratic behavior. An autopsy revealed the presence of abnormal protein clusters now referred to as amyloid plaques accumulated in her brain. These plaques are one of the two defining characteristics (the other being intracellular tangles made of tau protein within neurons) of what we now call Alzheimer’s disease (AD).

EXPERT ANSWERS

What age does Alzheimer’s Disease usually begin?

“Sporadic Alzheimer’s disease usually begins after age 60” writes Professor George Perry, neurobiology and Alzheimer’s Disease expert from the University of Texas, San Antonio. “The risk doubles for every 5 year period after then. Familial Alzheimer’s Disease, only accounts for about 1–5 % of the total, can begin at much earlier ages”.

Do videogames prevent Alzheimer's?

Extremely Unlikely says Dr Christopher Hertzog, an expert in neuroscience from Georgia Institute of Technology. "It is possible that the mental exercise engaged by challenging video games can sharpen some aspects of the mind. But nothing has yet been found that slows, let alone prevents, Alzheimer's disease (AD). The history of AD research shows that many hypotheses have been tested, many pharmaceuticals have been tested, all without meaningful effect on the disease and its progression. We do not understand the etiology of the disease and we have no way of combating it, at present. "

Does cooking with aluminum foil increase the risk for Alzheimers disease?

Extremely Unlikely says Dr Robert Yokel, a toxicologist from the University of Kentucky. Cooking is a minor contributor to aluminium exposure for humans he says and "Adequate kidney function protects against aluminum accumulation and toxicity. There is no good evidence that the consumption of aluminum from foods is associated with Alzheimer’s disease, nor is there convincing evidence that aluminum from any source is a significant contributor to Alzheimer’s disease."

EXPERT CONSENSUS

Is Alzheimer's genetic?

85% Affirmative via 20 experts

When it comes to medical conditions, few could envision a malady more horrifying than one that slowly drains you of your cognitive abilities and memories. So naturally, many wonder whether the development of Alzheimer’s is a genetic, forgone conclusion, or if there are steps that can be taken to decrease one’s chances of developing the disease.

About 85% of our experts agreed that genetics play a role in the development of Alzheimer’s, but it’s not always entirely clear to what extent genetics are involved. Erin Abner, an associate professor in the department of epidemiology at the University of Kentucky, explained that there are two forms of AD: early onset and late onset. Early onset occurs in a small percentage of cases and “is entirely genetic.”

As for the other 95% of cases? Well, there are certain genes associated with them. “Sporadic AD … is strongly linked to the APOE gene, specifically the e4 allele,” wrote Abner. “People with either one or two copies of the APOE4 allele are between 4 and 12 times more likely to develop dementia due to AD compared to people without e4 allele. There are also many other genes (around 20) that have been linked to sporadic AD, but their individual effects are not nearly as strong as APOE. Overall, we estimate that about 70% of a person's risk for sporadic AD is explained by genetics.” 

So if the other 30% is environmental, does that mean we can take meaningful steps to decrease our risk of developing AD? Margaret Gatz, a professor of psychology, gerontology and preventive medicine cited several studies suggesting “risk for developing Alzheimer’s disease is greater in those who do not engage in physical activity; in those with uncontrolled high blood pressure, diabetes, or obesity in midlife; and possibly among those exposed to greater air pollution.”

CONSENSUS

Are dementia rates in the US declining?

100% Affirmative via 7 experts

Given the years of research and the billions of dollars spent in search of a cure for Alzheimer’s, one would hope that we’ve made progress in both preventing and treating the disease. Many Metafact users were curious about whether dementia rates in the U.S. are actually declining.

All of our experts agreed that rates are declining, with some caveats. First, it’s important to acknowledge that, while rates are going down, the overall number of dementia cases is increasing. That’s because the population contains more elderly adults than ever before. 

When we talk about “rates,” we’re discussing the percentage of cases compared to the total population. “From several studies in the United States and around the world, there is some evidence to suggest that the age-adjusted prevalence of dementia in older adults is now less than for prior generations,” wrote Jennifer Anne Deal, an epidemiologist at Johns Hopkins University. “There is also evidence from several studies that the incidence (that is, the new cases of dementia) is also less now than for prior generations.”

That doesn’t mean we necessarily understand the reason for this rate decline. As John Goss, an associate professor at the Health Research Institute, University of Canberra, put it: “We are not entirely sure why, but it is encouraging news.”

CONSENSUS

Is there a correlation between depression and later development of dementia?

93% Affirmative via 14 experts

For most dementia patients, the onset of symptoms is slow and gradual, which leads one to wonder if there are any cognitive symptoms that can signal oncoming dementia far in advance. One Metafact user asked whether there’s any link between depression and later development of  dementia.

Most experts agreed there’s a correlation between dementia and depression, though it’s unclear whether this relationship is causal. Jen Yates, an assistant professor in mental health at the University of Nottingham, cited several studies noting such a correlation. “It might be that depression and dementia share common pathways within the brain, or alternatively it could be the acknowledgement that cognitive function is not at the same level that leads to feelings of sadness. Changes within the brain associated with dementia begin up to 15 years prior to symptoms being detected on neuropsychological tests, but people themselves may feel an awareness of such changes.” In other words, a dementia sufferer might be able to detect their cognitive decline far before it can be measured by medical experts.

If there is a causal relationship between depression and dementia, does that mean antidepressants could decrease a person’s chances of developing the disease? Perhaps. “Some probably improve cognition,” wrote Donald R Royall, a psychiatrist at the University of Texas Health Science Center at San Antonio. “Others may adversely affect it. However, to prevent or delay dementia's onset, they will have to improve [general intelligence]. I don't think the current generation of antidepressants are ‘smart drugs.’ One sign of this is that the time course to functional recovery after ‘successful’ antidepressant treatment is similar to that of untreated major depression. Antidepressants are validated for their effect on mood, not cognitive impairment, and certainly not [general intelligence].”

When in your life you experience depression may play a factor in the chances that you develop dementia. “Late life depression has a much stronger relationship with the subsequent development of dementia and that is likely due to the mood disorder being precipitated, at least in part, by evolving neurodegenerative (such as Alzheimer's disease, Parkinson's disease) and cerebrovascular disease that is part of the lengthy cascade into dementia,” wrote Brian Draper, a psychiatrist from UNSW Sydney. “So here, the depression is not causal of dementia, but a manifestation of the same underlying neuropathology occurring at an earlier time point.”

CONSENSUS

Can we help prevent Alzheimer's with diet?

100% Affirmative via 12 experts

Given that most Alzheimer’s cases aren’t entirely driven by genetics, it’s natural to wonder what can be done to decrease your chances of developing the disorder. More specifically, Metafact users wanted to know whether diet and exercise could help in preventing dementia.

All of our experts agreed that a better diet decreases your chances of developing Alzheimer’s. Yoram Barak, an associate professor at the University of Otago, cited studies showing that the MIND diet -- which consists largely of leafy vegetables, legumes, and berries -- “lowered the risk of AD by as much as 53% in participants who adhered to the diet rigorously, and by about 35% in those who followed it moderately well.” Why is this diet so effective? Joseph Quinn, a professor of neurology from Oregon Health & Science University, pointed to the diet’s positive impact on vascular risk as a significant driver of its cognitive benefits.

Rosanna Squitti, an expert from IRCCS Centro San Giovanni di Dio, pointed to several measures that could play a preventative role for dementia, including minimizing intake of saturated fats, an increase in the consumption of leafy vegetables, and 120 minutes of exercise each week. “Include aerobic exercise in the routine,” she wrote, “equivalent to 40 minutes of fast walking, three times a week.”

Some experts noted the link between obesity, cardiovascular disease, and Alzheimer’s. “Obesity in middle age and early old age is a very strong risk factor for Alzheimer's disease (AD),” wrote Auriel A Willette, an assistant professor of food science and human nutrition at Iowa State University. “Obesity often leads to decreased ‘good’ cholesterol, excess glucose in the blood that can cause pre-diabetes or type 2 diabetes, and other conditions that each raise AD risk.”

CONSENSUS

Is there a link between bad sleep and dementia?

100% Affirmative via 12 experts

Diet wasn’t the only environmental factor Metafact users wondered about. What about sleep? Is there some sort of correlation between bad sleep and dementia, causal or otherwise?

Yes, there is. “Sleep disturbances increase with advancing dementia severity, and may predict faster cognitive decline, mostly in the mild to moderate stages of Alzheimer's dementia,” wrote Fabricio Ferreira de Oliveira, an affiliate professor of the department of neurology and neurosurgery at the Federal University of São Paulo. “Insomnia may also lead to more patient institutionalisation, increase risk of falls and mortality, and impact caregiver burden.”

Most experts agreed that there’s not much concrete evidence as to whether lack of sleep causes dementia or is merely an early indicator of it. Andrew Lim, an assistant professor of neurology at the University of Toronto, cited animal studies showing that sleep disruption “can cause Alzheimer's-related brain changes in animals.” Nadia Gosselin, an associate professor in the department of psychology at the University of Montreal, noted that “several studies show that poor sleep can alter the biomarkers of Alzheimer's disease, but only about half of the epidemiological studies show an association between poor sleep and cognitive decline.” 

Why would poor sleep lead to dementia? It could be because one of the main benefits of sleep is cognitive repair. “Many of the protective mechanisms that the brain uses to maintain healthy function in aging are tied to sleep and to the night phase of the circadian rhythm, and sleep-wake cycle disruptions are one of the earliest signs of Alzheimer's disease and dementia,” wrote Danielle Gulick, an assistant professor of physical therapy & rehabilitation sciences at the University of South Florida. Laurent Seugnet, a neuroscience researcher, had a similar assessment. “Sleep is important for neuronal plasticity, memory consolidation, and has also been shown recently to facilitate the elimination of toxic molecules such as beta-amyloid peptides [which make up plaques]” he wrote. “Thus it is almost certain that there is a bidirectional link between sleep disorders and dementia / Alzheimer’s.”

Quick Answers

Does Cannabidiol oil likely to benefit someone with Alzheimers?  Rats maybe. Not enough evidence in humans.

Does air pollution cause Alzheimer's disease? Yes.

Does coffee lower the risk of Alzheimer's? Not enough evidence.

Can breaking down brain plaques prevent Alzheimer's? No.

Takeaways

1. Diet can help prevent Alzheimer’s, particularly the Mediterranean diet. That means you should try and eat lots of veggies, fruits, nuts, seafood (2 serves a week) and not much red-meat. Or just move to Italy, Spain or Greece.

2. Coffee neither causes or prevents Alzheimer’s. Enjoy your latte.

3. Brain games and video games good for cognition but doesn’t prevent Alzheimer’s. Sudoku anyone?

4. Aluminium does not cause Alzheimer’s. Yes, you can still enjoy roasting with Aluminium foil.

5. Good sleep is strongly linked to Alzheimer’s. Get >7-9hrs.

6. Air pollution is strongly linked to Alzheimer's. If you can, avoid being near busy roads for long periods of time at home or work. Or just wait til all cars become electric..that’ll take a while.

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Are antioxidants important for maintaining good health?

Green Tea. Dark chocolate. Pomegranate juice. You've probably heard from food marketers claiming they contain loads of health boosting ‘antioxidants’. It’d be a good excuse if something as delicious as dark chocolate could be healthy! So what does the evidence say about antioxidants in food? Are they important? Should we seek out antioxidant-rich 'superfoods' or supplements?

We asked some top researchers around the world who study antioxidants to share some facts and myths on this popular food marketing claim. This review was one of our most requested to re-share. Here's what we found...

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ORIGIN STORY

Cyanobacteria and the evolution of antioxidants

For the first 2 billion years of its life, earth's atmosphere had no oxygen. Oxygen started to appear about 2.4 billion years ago from a tiny photosynthetic Cyanobacteria. Up until that moment, life on earth was unicellular and anaerobic, meaning oxygen was toxic to life. Known as 'The Great Oxidation Event', those prehistoric organisms had a stark choice the moment oxygen began increasing in the atmosphere: evolve to produce 'antioxidants' to protect themselves against oxidation, or move to anaerobic environments or die.

Some organisms buried themselves deep in the mud to flee the oxygen (where they exist today), but many became extinct. Some cyanobacteria however evolved to produce anti-oxidants that allowed them to survive in an oxygenated environment. "Over time more advanced antioxidant systems evolved, allowing Cyanobacteria to adapt to an aerobic lifestyle and become the most important environmental engineers in Earth history" says geobiologist Professor Woodward Fischer from Caltech says in a 2016 article.

Plants evolved from cyanobacteria and therefore, also evolved to produce an array of antioxidant compounds including carotenoids, flavonoids, benzoic acids, folic acid, ascorbic acid. As more advanced life evolved within an oxygenated atmosphere, humans also evolved an effective antioxidant system to combat the damaging oxidation. Increased melanin in skin (tanning) in response to exposure to UV radiation is an example of an antioxidant response in the skin. The real debate today however, is whether consuming additional dietary antioxidants can help humans protect themselves against disease and live longer.

EXPLAINER

What are ‘antioxidants’?

Antioxidants are certain types of molecules that protect other molecules from a chemical process called oxidation. Oxidation is very common and important for us to live. Glucose for example, a sugar from the food we consume, is oxidized by the oxygen we breathe which gives us the energy to live. Food preservatives are also type of ‘antioxidant’ as they prevent the oxidation process and food spoilage.

In our body, however, the oxidation process can damage important molecules in our cells, including DNA and proteins. Antioxidants are important since they can prevent or reduce this damage. Uncontrolled oxidation is typically caused by highly reactive molecules known as ‘free radicals’.

What are ‘free radicals’?

Free radicals are unstable molecules that can damage cells. Antioxidants help mop up excess free radicals. The body can cope with some free radicals and even needs them to function effectively. However, the damage caused by an overabundance of free radicals over time may become irreversible and lead to certain diseases including heart disease and some cancers.

Having an imbalance of electrons makes the free radical unstable and places the body in a state of oxidative stress. Oxidation can be accelerated by stress, cigarette smoking, alcohol, too much sunlight, pollution and other factors. Oxidative stress and an excess of free radicals can lead to damage of:

• Nucleic acids leading to cancerous changes

• Membrane lipids and LDL-cholesterol in arteries

• Enzymes which repair cell structures

• Other proteins such as collagen

So where does our supply of antioxidants come from?

Antioxidants come from many different vitamins and minerals like vitamin C, vitamin E, beta-carotene and selenium. “Generally our body makes most of its antioxidant enzymes in the right amounts needed” says Professor Margreet Vissers from the University of Otago, but our diet is also important.

“Vegetables, fruit and tea are sources of dietary antioxidants. Even though chocolate and red wine also contain antioxidants, consuming them to increase antioxidant status is not recommended” says nutrition scientist from North-West University Dr Cornelie Nienaber-Rousseau. “However, microgreens [like basil, coriander or kale] are very good sources of antioxidants or phytochemicals”. Plant-based foods are rich in something called phytochemicals—"plant chemicals"—many of which also have antioxidant properties that interact importantly.

For example, Vitamin C is an antioxidant, while a phytochemical called hesperetin (found in oranges and other citrus fruits) restores the vitamin C to its active antioxidant form. Carotenoids (such as lycopene in tomatoes and lutein in kale) and flavonoids (such as anthocyanins in blueberries, quercetin in apples and onions, and catechins in green tea) are also antioxidants (Source).

CONSENSUS

Are more antioxidants better for you?

100% Negative via 3 experts

Antioxidants can short-circuit the damage caused by free radicals so it seems logical that taking more antioxidants from supplements would be healthier? Clinical trials have failed to substantiate this says Dr Homer Black, biochemist from Taylor College of Medicine. And some antioxidants have been shown to be harmful.

"A number of epidemiological studies (principally case-control) have found inverse associations with carotenoid levels (both dietary intake and blood levels) and cancer risk. However, clinical trials have failed to substantiate such a relationship and one even found an 18% increase in lung cancer among male smokers receiving beta-carotenoid supplements.

Recent experimental evidence seems to indicate that beta-carotene, per se, acts as a pro-carcinogenic agent in UV-carcinogenesis when provided as the only carotenoid and phytochemical in the diet. What the public must understand is not all antioxidant mediated reactions are beneficial and antioxidants such as beta-carotene can, under certain conditions, act as a pro-oxidant" says Dr Homer.

Nutrition scientist Dr Tim Crowe confirms this: "Vitamin A as beta-carotene has been associated with a reduced risk of certain cancers, but an increase in others, such as lung cancer in smokers, if vitamin A is purified from foodstuffs."

Experts caution about taking antioxidant supplements. “The notion that antioxidants per se have superpowers in terms of preventing or curing disease has been put to rest long ago” says Professor Jens Lykkesfeldt, a biochemist from the University of Copenhagen. "Ingesting enormous amounts of antioxidants does not necessarily improve your health...Clearly essential micronutrients such as vitamin C that are also antioxidants are good (essential) for you. However, the notion that antioxidants per se has super powers in terms of preventing or curing disease has been put to rest long ago. It is therefore important to distinguish between essential micronutrient that happens to be antioxidants (and are important for humans health) and other ‘generic’ antioxidants that very common in e.g. fruits and vegetables that are not individually essential."

CONSENSUS

Do antioxidants help protect against cancer?

Uncertain via 4 experts
"The idea that antioxidants, consumed in green leafy and yellow vegetables, are cancer protectants arose from a 1981 epidemiologic study in which individuals consuming a greater amount of these vegetables were at a lower risk for cancer" says Dr Homer Black, biochemist from Taylor College of Medicine. "As these vegetables were rich in carotenoids such as beta-carotene, and knowing that beta-carotene was a strong singlet oxygen quencher and antioxidant, it was proposed that this carotenoid, or related carotenoids, might act as a cancer preventive. Whether these carotenoids can reduce cancer risk is unclear and controversial."

"Cancer patients often take antioxidant nutritional supplements during cancer treatment to alleviate treatment toxicities, improve long-term outcomes and replenish antioxidant status that declines during cancer treatment " says Nutrition scientist Dr Cornelie Nienaber-Rousseau "However, summaries of the scientific studies on antioxidant supplements (beta carotene, vitamin A, vitamin C (ascorbic acid), vitamin E, and selenium) for prevention of cancers found no evidence that they prevent cancers (Bjelakovic et al., 2004). In fact some antioxidant supplements (beta carotene, vitamin A, and vitamin E) seem to increase overall mortality (Bjelakovic et al., 2004; Bejelakovic et al., 2007)" she writes.

CONSENSUS

Are antioxidants overhyped?

Likely via 5 experts

Experts suggest most of the hype on superfood antioxidants don’t match the science, particularly with regard to taking supplements as “intake needs to be controlled according to usage as some of these can be overdosed (Vitamin A, Vitamin E and selenium are toxic in high doses)” says Professor Vissers from University of Otago.

The good news is that evidence seems to suggest that whole foods are more effective than supplements says Dr Tim Crowe: "There is increasing evidence that antioxidants are more effective when obtained from whole foods, rather than isolated from food and presented in tablet form with some antioxidant supplements actually increase cancer risk". “Antioxidants should preferably come from food and not be supplemented”, says Nutrition Scientist Dr Cornelie Nienaber-Rousseau.

What about superfoods?

“Despite the marketing hype, antioxidants found in so-called superfoods [like goji berries, blueberries or pomegranate juice] are no more effective than those in regular fruit and veg, so you’re better off saving your money” writes Dr Jacqui Adcock from Deakin University in The Conversation.

EXPERT PERSPECTIVE

Fruits & vegetables are much more than just antioxidants

Polyphenols are micronutrients that we get through certain plant-based foods and should take more credit for any overall health benefit says Dr Tim Crowe: "A brief reading about polyphenols on the Internet will bring up article after article highlighting that polyphenols are antioxidants and that explains their health benefits" he writes. "But nutrition science though has well-and-truly moved on from using such simplistic language and concepts to describe how these thousands of polyphenols found in food work. They are much more than antioxidants. You need to step back and see the bigger picture. It should instead be about polyphenols and their multitude of benefits and actions in the body such as:

• Regulating cell growth and death

• Slowing down cancer cell proliferation

• Altering glucose responses and insulin sensitivity

• Increasing activity of enzymes involved in removing harmful substances from the body

• Decreasing inflammation

So it seems the whole fruit and vegetables offer alot more health benefits beyond just being antioxidants.

TOP ANSWER

Will antioxidants absorbed from vegetable and fruit protect us from cancer?

There is reasonable evidence that following a diet that contains more fruits and vegetables can be protective of some cancers. This is reviewed in a report by the World Cancer Research Fund (Third Expert Report on Diet, Nutrition, Physical Activity and Cancer: A Global Perspective).

The protective effects of fruits and vegetables are likely due to the combination of compounds present in those foods, not just compounds that have antioxidant activity. This combination would be very hard to replicate in a pill. In considering foods associated with cancer prevention, diet as a whole needs to be taken into account (in other words, the things one eats with the vegetables) as well as whether or not the calories eaten are expended (aka energy balance). It is difficult for the beneficial effects of a good diet to be exerted in the face of a positive energy balance that leads to weight gain.

Dr Zora Djuric, An expert from University of Michigan in Nutrition, Cancer

Takeaways

1. Antioxidants do serve important roles in our body and diet is an important source of them to maintain health.

2. Antioxidants are not just one molecule, our supply can come via many different vitamins and minerals. Plant-based foods are rich in antioxidants and also contain thousands of other plant chemicals that likely benefit our health more than antioxidants alone.

3. Experts suggests antioxidant supplements do not work as well as the naturally occurring antioxidants in whole foods such as fruits and vegetables.

4. Be very wary of antioxidant supplementation as evidence shows it can be harmful.

5. Experts say there’s lots of hype on antioxidants. You can save your money on superfoods - just maintain a diverse diet with lots of fruits and vegetables.

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All content is general in nature and educational information only. Remember to always talk to your healthcare professional on questions regarding your health - they are your best source of evidence. 

Humans have eaten eggs for millions of years, initially from wild birds including pigeons and fowl, and later from domesticated birds like chickens. We have been raising chickens since 7000 BC, and their eggs are a major component of diets around the world.

Eggs are one of the most versatile cooking ingredients we have - they can be scrambled, poached or fried on their own, or combined with other ingredients to make cakes, pies and mayonnaise (just to name a few).

Many of us eat eggs daily, but what effect is that having on our health? Can eggs help with weight loss? Are they good or bad for heart health? Do eggs need to be stored in the fridge? We asked scientists to share the facts on eggs, here is what we found.

This review was co-written by Associate Professor Cornelie Nienaber-Rousseau, an expert in nutrition and cardiovascular disease from North-West University

Read the full review

Meta-Index

$248,000,000,000: Global market for eggs in 2022

26: Hours for an egg to fully form

250: Number of eggs hens can lay in a year

74: Calories in one hard-boiled egg

6%: Proportion of recommended daily dose of Vitamin A

What’s in an egg?

One medium chicken egg contains about 70 kilocalories of energy. It also contains a significant amount of protein, approximately 6 grams per egg. Whether scrambled, fried, boiled or poached, eggs are a superb source of vitamins and nutrients.

Egg yolks are high in fats, because their biological purpose is to provide developing chick embryos with nutrients and energy. One of the fats they contain is cholesterol, which means that for many years eggs were considered unhealthy and could increase your risk of cardiovascular disease, a relationship which has since been contented.

Egg whites are made of 92% water, with a mixture of around 148 different proteins, and almost no fat or carbohydrates. 94% of proteins obtained from eggs become incorporated into the proteins of the body. Eggs are an important source of minerals such as phosphorus and zinc, and vitamins such as vitamin A, B12, D and pantothenic acid.

Not all eggs are the same - the nutrient content of eggs vary according to the diet of the hen.

Eggs are relatively low-cost, and are considered the most affordable protein source. For this reason their consumption is encouraged, especially when money is limited, to ensure adequate consumption of proteins and nutrients.

CONSENSUS

Do eggs help suppress hunger?

100% positive via 4 experts

When battling with hunger pangs associated with weight loss diets, high-protein foods are known to reduce appetite and increase fullness (satiety). Several studies have indicated that eggs, because they are protein-rich, can suppress hunger.

Professor Maria-Luz Fernandez, an expert in nutrition from Connecticut University, says “I conducted a study in which we used two types of breakfast, one was egg-based and the other bagel-based, the number of Kcal [calories] were the same… Subjects had lower levels of ghrelin (appetite hormone) after the egg breakfasts, and they ate 400 less kcal in the next 24 hours after the egg breakfast.”

Several similar studies have found that breakfasts containing eggs suppressed hunger more effectively than wheat based breakfasts, oatmeal or cereal. "Based on the evidence form the experimental studies" says nutrition scientist Dr Cornelie Nienaber-Rousseau, "the incorporation of eggs into breakfast may be more effective than cereal or grain-based breakfasts to increase feeling full for longer and to limit short term energy consumption. However, the potential role of a routine egg breakfast in producing a sustained energy deficit and consequent weight loss, should be determined by additional research."

INSIGHT

Can eating eggs help you lose weight?

Eggs help suppress appetite, so can they make you lose weight? Unfortunately, the relationship between eating eggs and weight loss is not yet clear.

Vander Wal and co-workers (2008) studied the effect of an egg-based breakfast as compared to a bagel breakfast on weight loss in overweight men and women following a weight loss diet. They found that after 5 weeks those consuming an egg breakfast had a 61% greater reduction in body mass index (BMI), a 34% greater reduction in waist circumference, and a 65% greater reduction in weight loss than those ingesting a bagel breakfast.

However, other studies have not come to such clear conclusions. Professor Peter Clifton, an expert in nutrition and endocrinology from South Australia University, says “There is good evidence of increased satiety from protein in general and eggs in particular. However, in a calorie-controlled diet the additive effect of protein is not seen and weight loss is the same after 3 months”

Incorporating eggs into breakfast may be more effective than cereal or grain-based breakfasts to increase feeling full for longer and to limit short term energy consumption. However, whether routine egg breakfasts can help weight loss needs to be determined by additional research.

CONSENSUS

Are eggs bad for heart health?

60% negative via 5 experts

There has been a lot of debate as to whether eggs are bad for heart health. A few years ago recommendations were not to eat more than a few eggs a week on the grounds that eggs contain lots of cholesterol - about 185 mg per egg yolk, which is more than half the daily recommended amount. At the time, it was believed that elevated circulating blood cholesterol is caused by cholesterol in our food. Since then scientists found that most of the excess cholesterol in our blood is produced by the liver in response to eating too much saturated fat (fats that are hard at room temperature) such as the fat in bacon. So perhaps we need to eat less of the bacon, not the eggs, for breakfast.

However, Dr John David Spence, an expert in heart disease from Robarts Research Institute in Canada, disagrees. He says even if blood cholesterol is not raised after eating eggs, they are unhealthy because "for four hours after a high fat/high cholesterol meal, there is a marked increase in oxidation of LDL into the bad form, the arteries are twitchy, and the arteries are inflamed." Dr Spence also describes how egg consumption is associated with increased trimethylamine-N-oxide (TMAO) production, which may be an important predictor of heart disease.

Several studies have measured the incidence of heart disease in people who consume different amounts of eggs. One meta-analysis found that there is an elevated risk of heart failure with frequent egg consumption. A different meta-analysis found that intake of up to 1 egg a day may be associated with reduced risk of total stroke, but no clear association was found between egg intake and risk of heart disease.

Some of these different conclusions can be explained by the difficulties in measuring the relationship between eating eggs and heart disease. Self-reported egg consumption using food frequency questionnaires might introduce errors when people struggle to remember exactly what they ate when. Accounting for cooking methods and additives when eggs are prepared is also difficult. One way of addressing these issues is to conduct experimental feeding trials where diets are strictly controlled and then the incidence of disease is measured. Experimental studies like these are able to show cause and effect, but they are extremely expensive and challenging to do.

Like any food, eggs are bad for health if eaten in excess or as part of an unhealthy diet. Excluding eggs may be a good choice for people already at risk of heart disease as a way of reducing fat and cholesterol intake, but for many other people cutting out eggs may mean missing out on essential nutrients.

Quick Answers

Do eggs contain antioxidants? Yes, eggs contain antioxidants like selenium and lutein, these can be beneficial for eye health.

Are eggs gluten-free? Yes

Are eggs chicken periods? No, chickens are not mammals so don't have periods or wombs.

Do you need to keep eggs in the fridge? Eggs should be kept below 20'C, so for most kitchens out of the fridge is fine. However many say best practice is to keep them in the fridge so they last longer.

Do eggshells stop slugs from eating garden plants? Many people sprinkle eggshells around their flowers to stop slugs reaching the plants and eating them. Unfortunately, this hack is a myth.

Takeaways

• Eggs do not need to be kept in the fridge, but it might make them last longer

• Eggs likely help suppress hunger

• We don't know if eating eggs can help with weight loss

• Eggs are not bad for heart health when eaten as part of a healthy diet

• Eggs are a cheap and rich source of nutrients and protein

Most people have either had a major operation or know someone who has – in fact an estimated 230 million major surgical procedures under general anaesthesia are carried out each year. Waking up from surgery can be disorienting, but could it also lead to higher risk of memory loss and Alzheimer’s disease? We asked 5 experts in anaesthesiology, Alzheimer’s Disease and medicine, ‘Is general anaesthesia linked to memory loss and Alzheimer's disease?’, here is what they said…

EXPERT CONSENSUS

Is general anaesthesia linked to memory loss and Alzheimer's disease?

‘Uncertain’ according to 5 experts

What is general anaesthesia and what is it used for?

The word ‘anaesthesia’ means ‘loss of sensation’. General anaesthesia (GA) is a state of controlled unconsciousness. It is used to carry out surgical procedures that would be too painful or dangerous to perform if you were conscious. An alternative anaesthesia, called regional anaesthesia, is used for operations where certain parts of the body are made numb, but the patient remains conscious.

GA is achieved through a mixture of medications, including those to keep you asleep, relieve pain and relax your muscles. The correct combination of these medications are delivered by an anaesthetist before the operation, and then GA is carefully maintained during the surgery before the patient is woken up again.

Why is it difficult to study the effects of general anaesthesia?

Dr James Cory-Wright, a medical doctor from Royal Berkshire Hospital NHS Foundation Trust in the UK, says “This is a tricky question to answer because general anaesthesia (GA) rarely occurs in the absence of surgery, so it is difficult to design studies to investigate whether GA in isolation is linked to memory loss and Alzheimer’s disease (AD). To complicate things further there are different types of GA including inhalation anaesthesia and total intravenous general anaesthesia (TIVA).”

Due to this difficulty, most studies looking at the effect of GA also look at the effects of surgery, and whether GA and surgery together can be linked to memory loss and AD.

Is general anaesthesia (and surgery) linked to memory loss?

Professor Lisbeth Evered, an expert in anaesthesiology and Alzheimer’s Disease from St Vincents Hospital Melbourne in Australia, says “There is a large body of evidence demonstrating that some older people suffer objectively defined cognitive decline following anaesthesia and surgery.”

Dr Cory-Wright says “there is good evidence that the combination of GA and surgery results in short-term effects on memory, termed post-operative cognitive decline (POCD), which is common in the elderly population with an incidence of 30% at 1 week in one study. This link between surgery involving GA and POCD has been recognised as far back as 1887, with an article published in the BMJ titled ‘Insanity following the use of anesthetises in operations’. ” He goes on to explain that POCD risk increases with age along with other factors such the length and type of operation.

Dr Roderic Eckenhoff, an expert in anaesthesiology from Pennsylvania University in the USA, says “Anaesthesia by itself is unlikely to accelerate AD or memory loss in humans. Most data from animals suggests only a transient effect.  However, considering both anaesthesia and surgery, the data do suggest a longer lasting effect in those patients with pre-existing vulnerabilities.”

Is general anaesthesia (and surgery) linked to Alzheimer’s Disease?

Professor Evered says “There is animal evidence of Alzheimer's disease-type neuropathological changes associated with gaseous anaesthetics, but none of this work has been replicated in humans.”

Dr Cory-Wright agrees, saying “large observational studies investigating this have yielded mixed results. A well-designed study in Denmark looked at cognitive function in twins and found that GA and surgery did not lead to higher dementia risk and that other factors such as underlying disease were far more important. Another study with over 11 years of follow-up, looked specifically at whether POCD was linked to AD also found no evidence.”

How might anaesthesia affect memory?

Dr Cory-Wright says “There are multiple proposed mechanisms by which GA and surgery cause POCD. Animal studies have shown that some inhalational anaesthetic agents can directly cause neuronal cell death as well as AD-like changes in the brain such as accumulation of brain plaques.”

He goes on to say that “meta-analyses have found that whether you have general or regional anaesthesia does not affect your chance of getting POCD. This suggests that, while GA may play a role, other factors such as the surgery and being admitted to hospital may be more instrumental in the cause of POCD.”

How might surgery affect memory?

Dr Cory-Wright says “Surgery itself causes inflammation which can open the blood-brain barrier, resulting in the influx of pro-inflammatory chemicals into the brain. This affects neuronal signalling and the brain itself. Other proposed mechanisms by which GA and surgery cause POCD include low blood pressure and oxygen levels during the operation as well as pain and sleep disturbances afterwards.”

Is more research needed?

Dr Evered says we “need to know if the memory changes which occur in association with anaesthesia and surgery are the same as memory changes in the community like mild cognitive impairment and dementia or AD.” Dr Cory-Wright agrees and says “It is well known that GA and surgery are linked to short-term effects on memory and GA may well play a role in this. However, it is unclear whether GA is linked to AD and more research is needed in this area.”

The takeaway:

General anaesthesia and surgery is linked to short-term effects on memory, particularly in older adults. There is not strong evidence that general anaesthesia is linked to permanent memory loss or Alzheimer’s Disease.

May the facts be with you!

Eva

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Learn more about Alzheimer's Disease in our deep-diving review.

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Many of us don’t just like our morning cup of coffee – without it, we seem to function poorly. The alertness and stimulation of caffeine is well known – making it a daily ritual for most of the world making coffee is the world’s most popular beverage (excluding water).

In Australia for example, 75% of people drink coffee daily, while some 60% of Americans do. But its European nations that are the power coffee drinkers. Finland has the world's highest coffee consumption, with many drinking up to 10 cups of coffee per day! The obsession with coffee across the world has made it the second most traded commodity worldwide after oil.

For any drink so popular as coffee – people have claimed all sorts of things. Some say coffee fights Alzheimer's, helps weight loss, and makes us live longer! Are these true? What is the evidence behind them? Is there a science to making a good cup of coffee? And what level of coffee consumption is safe?

This is one of our most popular reviews where we asked independent experts from across the globe to review the facts. Here's what we found...

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NUMBERS

Meta-Index

2,000,000,000: Approximate number of cups of coffee consumed every day across the world

$127,000,000,000: The value of the global coffee market in 2022

51: Number of countries that produce coffee beans

40%: Brazil's proportion of global coffee production – making it by far the largest supplier of coffee

45%: European proportion of global coffee imports – making it the largest importer of coffee

32,938: Number of Starbucks coffee houses around the world

1884: The year when espresso was invented by Italian Angelo Moriondo for a “new steam machinery for the economic and instantaneous confection of coffee beverage.”

1890: The year when instant coffee was invented by David Strang in New Zealand

ORIGIN STORY

From Ethiopia to Starbucks

The word coffee derives from the word Kaffa - "a drink from berries" - also the name of a region in the South Western Ethiopian highlands where coffee was thought to be first discovered. As the popular story goes, in the 9th century an Ethiopian goat herder named Kaldi gave his goats a light red fruit from a shiny dark-leaved shrub (the coffee arabica shrub). To his surprise the normally dull goats became exceptionally lively, energetically skipping around. Suspecting hidden powers in this unknown fruit, Kaldi tried them himself – and sure enough, he felt energised and alert.

Coffee beans started to be roasted and infused into drinks during the 16th century. Coffee spread rapidly throughout Turkey and the Ottoman empire as a replacement for alcohol, which was banned throughout the Muslim world. The first documented coffee house (called kaveh-kanes) opened in Istanbul, Turkey **in 1554.

Europe discovered coffee for the first time via Italian merchants in the 17th century. It was met with strong resistance by the Catholic Church who called it 'the devil's drink'. Venice's first coffee house ("bottega del caffe`") opened in 1645 and coffee spread quickly throughout Europe with England's first coffee house opening in 1650. It wasn't until 1676 that Boston opened the first coffee house in the United States. That is a long way from today's biggest coffee company, Starbucks, with 32,938 coffee-houses across the world making everything from black coffee to caramel whipped cream lattes.

BACKGROUND

Is there science behind good coffee?

Coffee beans are the first component of good coffee. Coffea arabica makes up 75% of the world's coffee trade (Coffea robusta makes up the rest). Once the beans are sourced, the roasting takes place, where heat transforms the green bean into roasted brown beans that can be ground.

Once ground, there are 3 broad methods to make drinkable coffee: espresso, filtered and instant. The active caffeine component of coffee is ~2-3%, the rest made up mostly of tannins, proteins and oils. A variety of other bioactive chemicals, aromas and scents are also present in coffee. Both the caffeine content and flavor vary widely depending on a number of factors.

Dr Christopher Hendon, a chemist from the University of Oregon writes in detail about the chemistry and physics of making coffee.

What to do at home for a better coffee?

For filtered coffee three factors are most important according to Dr Hendon: water chemistry, particle size distribution produced by the grinder and coffee freshness.

Water quality: "Given coffee is an acidic beverage, the acidity of your brew water can have a big effect. Brew water containing low levels of both calcium ions and bicarbonate (HCO₃⁻) – that is, soft water – will result in a highly acidic cup, sometimes described as sour. Brew water containing high levels of HCO₃⁻ – typically, hard water – will produce a chalky cup, as the bicarbonate has neutralized most of the flavorsome acids in the coffee.

Ideally we want to brew coffee with watercontaining chemistry somewhere in the middle. But there’s a good chance you don’t know the bicarbonate concentration in your own tap water, and a small change makes a big difference. To taste the impact, try brewing coffee with Evian – a bottled water with one of the highest bicarbonate concentration, at 360 mg/L" says Dr Hendon.

Particle size: The particle size distribution your grinder produces is critical, too. Dr Hendon explains there are two different schools of thought on particle size. "One school of thought supports grinding the coffee as fine as possible to maximize the surface area, which lets you extract the most delicious flavors in higher concentrations. The rival school advocates grinding as coarse as possible to minimize the production of fine particles that impart negative flavors. Perhaps the most useful advice here is to determine what you like best based on your taste preference" he says.

Bean freshness: "Roasted coffee contains a significant amount of CO₂ and other volatiles trapped within the solid coffee matrix: Over time these gaseous organic molecules will escape the bean. Fewer volatiles means a less flavorful cup of coffee. Most cafes will not serve coffee more than four weeks out from the roast date, emphasizing the importance of using freshly roasted beans" he says.

One can mitigate the rate of staling by cooling the coffee (as described by the Arrhenius equation), while storing coffee in an airtight container in the freezer will significantly prolong freshness, says Dr Hendon.

What about espresso?

Espresso is the most complicated brewing method because it requires precise measurements and is also the basis for lattes and cappuccinos. To make espresso, hot water is forced through a finely-ground bed of coffee.

The barista decides the types of beans and how finely ground the particles are. The machine’s water pressure, temperature and brew volume are also crucial when it comes to taste. Thousands of chemicals and aromas are produced via a delicate balancing act for the barista.

Dr Jamie Foster from the University of Plymouth teamed up with Dr Hendon to derive the factors most important for a good espresso. They found that the quality of the coffee plant/green bean to be by far the most important factor for good espresso.

"Provided all other brewing parameters are sensible, I would say that quality beans is the most influential factor on taste" wrote Dr Foster. After beans, water quality is the next most important. "Yes. Extremely. Aside from bean quality, I would say that it is probably the most important thing. Luckily, obtaining quality water can be achieved quite easily by filtration. I refer interested readers to the book Water for Coffee: Science Story Manual" says Dr Foster. The quality of roast is also important says Dr Foster. Interestingly, the quality of espresso machine is the least important of the four factors.

CONSENSUS

Is coffee ok during pregnancy or breastfeeding?

80% Likely via 5 experts

Caffeine is a known stimulant, so it's often claimed that drinking coffee during pregnancy or breastfeeding might be harmful to babies. "Overall, low levels of coffee consumption are not convincingly or consistently associated with any adverse pregnancy outcomes or outcomes during childhood" writes women's health epidemiologist Dr Kesha Baptiste-Roberts from Morgan State University. "As such one should adhere to the American College of Obstetrics and Gynecology recommendation of <200 mg of caffeine per day" - which is ~1-2 cups a day.

"Caffeine passes into breast milk, and caffeine has a longer half-life in infancy with even more delayed elimination in breastfed infants" writes Dr Baptise-Roberts. "However, the clinical use of caffeine in neonates appears to be relatively safe. There are still too few studies with limited quality to make conclusive statements" she writes.

"A recent massive review of caffeine intake in pregnancy confirms previous advice that intakes of less than 300mg caffeine per day in pregnant women is safe" says Dr Ian Musgrave, a pharmacologist from University of Adelaide. "But cut back on the double espressos and don't binge on chocolate [dark chocolate contains caffeine]" he says.

CONSENSUS

Do coffee drinkers live longer?

75% Likely via 3 experts

A number of studies (like this and this) have suggested that people who drank coffee had a lower risk of dying of any cause – and specifically, of dying from heart disease and cancer. More evidence has been published recently say the experts.

"A huge review published in BMJ in 2018 showed that coffee consumption was more often associated with benefit than harm for a range of health outcomes" writes coffee health expert Dr Joanna Mikolajczyk-Stecyna from Poznan University. "However, we have to remember that some of us are (so called) "fast" and the other "slow" caffeine metabolizers. Therefore drinking coffee, which apart from hundreds of biologically active compounds, includes also caffeine, affect us in different way. Habitual coffee consumption seems to be beneficial for adult, but not for children and adolescents. Because drinking coffee is associated associated with lower risks for cardiovascular diseases, main reason for death, it can be linked to longevity" she writes.

"Drinking moderate amounts of coffee – about three or four cups a day – is more likely to benefit our health than harm it, our research shows" wrote Dr Robin Poole from University of Southampton. Those benefits include lower risk of heart disease, type-2 diabetes, liver disease, some cancers, Parkinson's and Alzheimer's.

Despite the correlative evidence, "we still can’t say coffee was the cause of the lower risk of death" writes pharmacologist Dr Ian Musgrave from the University of Adelaide. "There may be some other environmental variable that was not accounted for. Coffee consumption may entail more walking, for instance, which was not captured in the lifestyle questionnaires. But it is still plausible coffee causes the lowered death risk. While coffee is most notable for its caffeine content, it also contains a host of antioxidants such a caffeic acid and cholorogenic acid, which might have health benefits."

CONSENSUS

Does coffee help with weight loss?

50% Uncertain via 3 experts

In 2019 researchers from the University of Nottingham in the UK published a study suggesting caffeine increases brown fat. Brown fat activity burns energy, which may help with weight loss - so it got headlines. Dr Andrew Carey, an obesity expert from the Baker Heart and Diabetes Institute writes in detail about this study. Although caffeine did stimulate brown fat, it was in lab cells and "for a human to reap the benefits seen in the cells, we estimate they’d need to drink at least 100 cups of coffee.. current evidence suggests we shouldn’t start thinking about it as a weight loss tool, nor that it has anything meaningful to do with brown fat in humans" writes Dr Carey.

Another more recent study reported that consuming caffeine half an hour before aerobic exercise can actually help people burn fat. Dr Neil Clarke writes in detail about this study. He suggests that burning more fat after ingesting caffeine might be because "Caffeine promotes lipolysis (the process by which fats are broken down), due to a greater release of adrenaline. Lipolysis then causes fatty acids to be produced as a result. These fatty acids are then released into the blood and transported to muscle to be used as energy" he writes.

Caffeine also allows greater energy expenditure via deactivating the compound adenosine and stimulating the central nervous system allowing more muscle fibres to be used during excercise. "But it’s important to note that the effects in this most recent study may have been increased due to this exercise being performed in a fasted state. When exercising without eating before, fat oxidation is naturally higher" says Dr Clarke.

Other experts say "Coffee likely has a minimal effect on weight loss by itself" writes nutritionist Dr Neil Schwarz from the University of South Alabama. "The caffeine in coffee may increase metabolism, but it is unlikely to be enough to stimulate meaningful weight loss. Additionally, once any creamer or sugar is added to coffee, the additional calories offset any increase in metabolism. Black coffee may help slightly increase metabolism and decrease appetite. These are both helpful for inducing a caloric deficit for weight loss, but, overall, it is the balance in energy output versus input that will determine weight loss."

CONSENSUS

Is 400mg of caffeine the safe threshold?

100% Affirmative via 6 experts

How much coffee is safe? Neuroscientist and coffee expert Dr Astrid Nehlig from INSERM in Paris writes a good overview for us:

"The European Food Safety Authority and others around the world have published recommendations about the maximal safe daily doses of caffeine as well as the maximal doses recommended in one sitting. These figures have been estimated based on the brain and cardiovascular effects of caffeine. As confirmed by the experts, 400 mg a day is a safe limit for caffeine intake - but there are some differences based on the demographic and age:

Type of population| Maximal dosage advised in one sitting (mg)| Maximal daily dosage advised (mg or mg/kg)

Adults |200 mg (2 cups coffee) |400 mg (4 cups)

Intense sports activity in adults |200 mg up to 2 h before the exercise |Not determined

Pregnant women |200 mg (2 cups) |200 mg (2 cups)

Nursing women |200 mg (2 cups) |200 mg (2 cups)

Adolescents and children |Not determined |3 mg/kg

CONSENSUS

Does coffee help with exercise and sports?

100% Likely via 3 experts

Caffeine is one of the most researched substances reported to help athletes perform better and train longer and harder writes Dr Neil Clarke, sports scientist from Coventry University. As a result, professional and amateur sportspeople often take it as a performance-enhancing “ergogenic” aids for a wide range of activities. These include intermittent exercise such as football and racket sports, endurance exercise such as running and cycling, and resistance exercise such as weightlifting.

"Research has shown that pure caffeine can help endurance athletes run faster and cycle for longer" writes Dr Clarke. "It can help footballers to sprint more often and over greater distances, and basketball players to jump higher”. But will drinking coffee have the same effect as caffeine tablets? Yes says Dr Clarke “providing that the amount of caffeine is matched”.

What about the potential effects on the heart? "Caffeine improves exercise performance," writes cardiologist Dr Vitor Valenti. "However, if you have a cardiovascular disorder, we suggest you not intake caffeine before effort, in order to avoid any health complication during recovery."

QUICK ANSWERS

Does coffee cause dehydration? No. It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance. However, a number of studies suggest that coffee, when consumed in moderation i.e. around four cups per day provides similar hydrating qualities to water and that drinking coffee as part of a normal lifestyle doesn't cause fluid loss in excess of the volume ingested.

Does coffee lower the risk of Alzheimer's Disease? There is no clear evidence of this. There are some suggestions that coffee drinkers have lower rates of diseases like Alzheimer’s disease. However, the key question is why. Correlation does not equal causation.

Does coffee reduce the risk of cancer? Unlikely.

Does the acrylamide in coffee cause cancer? Unlikely, too. Acrylamide isn't good for you but the amount present in coffee makes no observable contribution to cancer risk. There is no strong evidence for a link between drinking coffee and developing cancer. While there have been occasional studies suggesting an increased risk in bladder cancer, overall the vast majority of rigorous studies suggest that if coffee drinking has any effect at all it actually offers a mild protective effect from some cancer types.

Does caffeine impact sleep quality? Yes, studies have shown that caffeine intake, as low as 100 mg can:

1. delay the timing of the body circadian clock

2. reduce sleep efficiency and sleep duration

3. perhaps even more dramatic, decrease the electrical "depth" of sleep (as measured by the spectral power of the delta brain waves during non-REM sleep).

   ---

TOP ANSWER

Is coffee drinking genetic?

My answer is yes. Twin studies have shown that coffee drinking is approximately 35-60% genetics depending on the differences in coffee cultures between populations. For Australians, 51% of coffee drinking is genetics and the remaining 49% is due to exposure to environmental factors such learning to know the pros and cons of coffee or peer influences.

Genes that have a major influence on coffee drinking are those involved in the caffeine metabolism. People with the genetic variants that make them metabolize caffeine quicker often drink more coffee. Genes involved in taste perception also affect coffee preference and hence coffee consumption. For example, people with the bitter supertaster gene often find coffee more bitter and drink less coffee.

I need to note that while humans are born to dislike bitter taste, as a natural defensive system to avoid eating poisonous food, our preference could change over time due to exposure to environmental factors. Therefore, some people might enjoy drink coffee because of its bitterness!

Dr Daniel Hwang from University of Queensland

Takeaways

• To make good espresso coffee, experts say the quality of beans/freshness are the most important factor followed by water quality and roasting. The equipment is the least important.

• Coffee drinkers live longer according to studies, but it's uncertain whether coffee is causing people to live longer without controlling for their lifestyle.

• Coffee doesn't cause dehydration. It improves exercise performance/duration and therefore may help some in promoting weight loss.

• The impact of coffee heavily depends on whether you are a slow or fast metabolizer. Alter your habits to ensure you don't have coffee in the afternoon if you fall into the slow metabolizer category which would impact your sleep.

• 3-4 cups of coffee is healthy or 400mg of caffeine. For pregnant women, 1-2 cups is the safe level of what experts recommend.

• Enjoy your coffee!

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In 2021, there were 247 million cases of malaria worldwide and 619,000 estimated deaths as a result of this disease. Malaria is one of the most severe public health problems we face, but in most cases it is easily treatable with antimalarial drugs.

Are these life-saving drugs becoming less effective against malaria? We asked 38 experts in medicine, biotechnology, statistics, chemistry and global health, ‘Is malaria becoming more drug-resistant?’, here is what they said…

EXPERT CONSENSUS

Is malaria becoming more drug-resistant?

37 out of 38 experts say ‘yes’

What is malaria?

Malaria is an infectious disease that causes fevers, headache and other flu-like symptoms. Children are particularly at risk of developing severe infection which can be life-threatening. Professor Shashi Pandey, an expert in biotechnology from Banaras Hindu University in India, says “Malaria is a serious, but preventable and treatable mosquito-borne disease. Malaria is predominant in areas with tropical and sub-tropical climates”.

Dr Eric Grist, an expert in statistics from Oxford University in the UK, adds that “Malaria is caused by a microscopic plasmodium parasite conveyed into humans by certain species of mosquito.” There are 5 species of Plasmodium parasites but most cases of the disease are caused by one called Plasmodium falciparum (P. falciparum for short).

What drugs are used combat malaria?

Professor Pandey says “WHO recommends artemisinin-based combination therapies (ACTs) for malaria which includes combination of two active antimalarial ingredients with different mechanisms of action, ACTs are the most effective antimalarial medicines available today. WHO currently recommends 5 ACTs for use against P. falciparum malaria. The choice of ACT should be based on therapeutic efficacy studies against local strains of P. falciparum malaria.”

ACTs are not the only tools we have against malaria, other drugs include chloroquine and mefloquine.

Is malaria becoming more drug-resistant?

37 out of 38 experts agreed that malaria is becoming more drug resistant. Professor Elizabeth Ashley, an expert in tropical medicine from Oxford University in the UK, says “Studies of patients with malaria in Cambodia, Vietnam and Thailand have shown increasing numbers of treatment failures in people treated with standard combination therapies.”

The level of drug-resistance depends on the drug in question and where in the world you are looking. Dr Grist says “In the case of long-established antimalarial drugs such as chloroquine, there is no doubt that antimalarial drug resistance to the drug exists in certain parts of the world and especially in some areas of Africa. The use of chloroquine in those areas now has virtually no effect as a treatment.”

When did malaria start becoming drug-resistant?

Drug-resistant malaria is not a new problem - it has been around for decades. Professor Timothy Egan, an expert in chemistry from Cape Town University in South Africa, said “Drug resistant strains .. have appeared over the last half century. Resistance to chloroquine appeared in the 1960s and became widespread in the 1980s, while resistance to the antifolate class of antimalarials appeared soon after.”

Professor Ashley, says “Two-drug combinations of an artemisinin compound (e.g. artesunate, artemether, dihydoartemisinin) plus a partner drug (e.g. mefloquine, piperaquine, lumefantrine) [also called ACTs] were introduced in the 1990s and early 2000s to try to overcome the problem of rapid resistance emergence in Plasmodium falciparum... This was very successful until around 2008-9 when scientists noticed that it took longer for the malaria parasite to be cleared from the blood in patients in Cambodia with the disease, related to decreased responsiveness to artemisinin. They were still cured eventually though. However, since then resistance of the parasite to at least 2 of the partner drugs commonly used (mefloquine and piperaquine) has followed.”

Why do parasites like malaria become drug-resistant?

Professor Egan said that resistance is “an inevitable result of natural selection. When any fast growing organism is exposed to a substance that is toxic to it, such as a drug, any individual organisms harbouring mutations that confer a degree of tolerance will be selected until they become dominant in the environment. Thus, the more drugs we expose the organism to, the more drugs it will ultimately become resistant to. This is what has happened in the case of malaria parasites.”

Professor Harin Karunajeewa, an expert in infectious diseases from the Walter and Eliza Hall Institute of Medical Research in Australia, adds: “whenever we come up with a new drug for malaria, drug resistance should always be considered a case of ‘when’ rather than ‘if’”.

Are we still able to treat malaria?

Malaria can still be effectively treated using ACTs. Professor Olivo Miotto, an expert in genomics and parasitology, adds that “it must be clarified that resistant to artemisinin is different from resistance to some of the other drugs mentioned, in that artemisinin still works and remains able to kill those parasites; however, it acts slower on the resistant parasites, such that they are sometimes able to survive the treatment. Artemisinin is always given in combination with another drug, so treatment failures happen when there is resistance to that partner drug. Unfortunately, in some Asian countries, this is happening, especially with the partner drug piperaquine- other combinations are more effective.”

What might happen in the future?

Professor Francois Nosten, an expert in medicine and global health from the Shoklo Malaria Research Unit in Thailand, says “Some argue that malaria is declining worldwide and that there is no reason to be concerned. Others observed that the decline in malaria has stalled, that artemisinin resistance can spread from South East Asia to Africa, like chloroquine resistance did in the past, causing millions of deaths, and that we cannot take the risk to see history repeats itself. They advocate rapid elimination of the parasites wherever they are.”

Professor Ashley adds that “If artemisinin resistance emerges in Africa and combination treatments start to fail there the prospects for successful containment are very limited and this could allow malaria to get out of control (~190 million of the estimated 207 million cases of malaria caused by P.falciparum in 2016 were in Sub-Saharan Africa). If this was to happen one of the likely outcomes would be a sharp increase in the number of child deaths from malaria (which is already high at >440,000 a year).”

How can we tackle drug-resistant malaria?

The spread of artemisinin resistance could be disastrous, so what can be done to avoid the worst case scenario?

Professor Karen Barnes, an expert in pharmacology from Cape Town University in South Africa, summarises a few things that can be done:

“In short, much is being done, and even more needs to be done better to address this problem, including:

• Achieving high coverage with all effective malaria control tools (e.g. mosquito vector control measures, personal protection, single low dose primaquine, prompt malaria testing, treating and tracking), to reduce malaria transmission - particularly in areas threatened by drug resistance.

• Using the malaria medicines that we currently have available better so that they can last as long as possible - always finishing the treatment, even if patients feel better sooner and always giving exactly the right number of tablets for each patient - bearing in mind that some types of patients (young children, pregnant women, people with other diseases such as malnutrition, obesity) may need more or less than the standard dose.

• Using malaria treatments that combine medicines that have opposing mechanisms of drug resistance.

• Enhanced surveillance for drug resistance to ensure prompt changes in treatment policy when needed.

• Intensive efforts to develop new medicines to treat malaria, although these will still take years before they become widely available”

The takeaway:

Malaria is becoming more drug-resistant, but multiple approaches are being taken to address the problem.

May the facts be with you!

Eva

Do I need to get vaccinated if everyone else is?

Vaccination may be one way to tackle drug-resistant malaria, learn more about vaccines in our deep-diving review.

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According to a 2022 sleep study, 71% of adults living in the UK do not get the recommended 9 hours sleep a night, and 14% of those do not even sleep 5 hours a night!

This problem is not UK specific – 62% of adults around the world say they don’t sleep as well as they would like to. We know that if we don’t get a good night’s sleep, we feel tired the next day and may find it harder to focus, but could a lack of sleep also be affecting our health? We asked 10 experts in sleep research, gastroenterology and epidemiology, ‘Is lack of sleep linked to higher mortality?’, here is what they said…

EXPERT CONSENSUS

Is lack of sleep linked to higher mortality?

10 out of 10 experts say ‘yes’

What is the evidence connecting sleep and mortality?

Dr Tetyana Kendzerska, an expert in sleep research from Ottawa University in Canada, says “Despite some inconsistencies in the published literature, the accumulated evidence suggests an increased risk of all-cause mortality associated with self-reported short sleep duration (usually defined as ≤ six h/night), among both males and females, compared to individuals who report, on average, a ‘medium’ amount of sleep per night (generally defined as 7 to 8 h/night) (systematic review and meta-analyses: Gallicchio et al., 2009; Cappuccio et al., 2010; Alves da Silva et al., 2016; Yin et al., 2017).”

Dr Taha Qazi, an expert in gastroenterology from the Cleveland Clinic in the USA, says “Lack of sleep or poor sleep is likely associated with a higher mortality. Namely poor sleep has been linked with an increased incidence and progression of CVD [cardiovascular disease], diabetes, obesity, cancer and premature mortality.”

Extreme lack of sleep shows an even stronger link to mortality. Professor Zahra Moussavi, an expert in sleep research from Manitoba University in Canada, says “Studies on mice have shown that complete sleep deprivation kills them within a week or two.”

Why is connecting sleep and mortality complicated?

Dr Jason Wong, an expert in epidemiology from the National Cancer Institute in the USA, says “Mortality is a complicated outcome and there are many forms of mortality related to hundreds of different cancers, cardiovascular disease, deaths of despair, metabolic disease, accidents etc. Each of these forms of mortality depend on incidence or occurrence of that certain disease.” Essentially, ‘mortality’ is a very broad outcome that could have many different causes (such as diseases or accidents), so it is difficult to connect it to particular characteristics such as sleep.

The other complication is that a ‘link’ between sleep and mortality could be correlation rather than causation (i.e. if you suffer from a certain condition that increases mortality, this condition may also affect your ability to sleep. This doesn’t mean that your lack of sleep is causing increased mortality). This is emphasised by Dr Dennis Auckley, an expert in sleep research from Case Western Reserve University in the USA, who says the studies described above “do not, and cannot, establish a cause and effect relationship, but show an association.”

Dr Kendzerska expands, saying “Some but not all of the excess mortality among the short sleepers may be due to differences in the characteristics of the individuals who comprise this group; for example, individuals who report shorter sleep time are more likely to be in low income and poorer overall health and to have been diagnosed with medical conditions, including depression, than individuals who report average sleep times.”

How can sleep affect mortality?

Is there a biologically plausible way in which sleep could cause increased mortality? Dr Auckley says “there are plausible biologic and physiologic mechanisms by which this may be a cause and effect relationship (chronic lack of sleep leading to higher mortality).  Growing data in well controlled trials have found that sleep deprivation leads to pathophysiologic changes that result in worsening metabolic and cardiovascular outcomes (i.e. diabetes risk, weight gain, hypertension) that could be mediators for higher mortality rates.”

Dr Kenderska says “The specific mechanisms underlying the association between short sleep duration and all-cause mortality are unclear. Potential mechanisms suggested are adverse endocrinologic, immunologic, and metabolic effects associated with short sleep as well as chronic inflammation.”

The takeaway:

Lack of sleep is linked to higher mortality rates, but whether this relationship is causative is not completely clear.

May the facts be with you!

Eva

Why do we need sleep?

Learn more about sleep with our deep-diving reviews (Part 1 and Part 2).

If you like our newsletters you can make a donation to support our work here at Metafact.

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The flu, like the common cold, is a viral respiratory illness and is contagious. It has taken a back-seat in recent years, but millions get sick and hundreds of thousands die each year. While the cold can be caused by a range of viruses (including rhinoviruses and seasonal coronaviruses), the flu is specifically caused by the influenza virus.

There are various types of influenza virus, helpfully called A, B, C and D. The two main types of human flu viruses are A and B - these are the ones that are responsible for seasonal human epidemics every year. Influenza viruses have three proteins sticking out of their surface: the matrix protein (M2), hemagglutinin (H) and neuraminidase (N). The two latter can change. That’s how you get H1N1, for instance, a common subtype that circulates between people. However, with up to 18 different hemagglutinin subtypes and 11 different neuraminidase subtypes, there are dozens of possible combinations the virus can choose from. Lots of mutations of influenza means vaccines have to be developed and updated each year.

We asked our experts all about influenza. Just how deadly is it? Does the vaccine work? What is ‘Flurona’? Are we more likely to get a flu if we’re out in the cold? Should we worry about catching it from other species? Does vitamin C help? Read on to learn all the facts.

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NUMBERS

Meta-Index

1930: Year when the influenza virus was first isolated

17: Proteins encoded in the genome of influenza A viruses

130: Influenza A subtype combinations identified in nature

2: Days after catching the virus when people can start getting symptoms

3 – 4: Days after getting a flu when people are most contagious

290,000 – 650,000: Deaths caused by influenza every year worldwide

889 million: Value of the global influenza medication market in 2018 (USD)

0.5: mL of vaccine in a standard jab for adults

BACKGROUND

The great pandemic

In the Spring of 1918, near the end of World War I, a minuscule threat was causing just as much damage across the world. Most of those infected had the traditional, mild symptoms of influenza, but an unusually high number died after developing pneumonia. Over the three years following the initial outbreak, a third of the world’s population (an estimated 500 million) had been infected. In the US, life expectancy dropped by over 12 years. This episode is generally referred to as the great influenza pandemic or the 1918 pandemic, although it is also known as the ‘Spanish flu’ - likely due to the fact that Spain was neutral in the War and so their press was free to report on the outbreak.

With no vaccines and only a limited understanding of the threat, quarantine measures and rudimentary cloth masks were about everything the public could do to protect themselves - this may sound all too familiar to most of us, after covid. Although the lethality of the 1918 virus was not much lower than that of the SARS-CoV-2, the shorter incubation period of influenza allowed the flu to spread even more rapidly through the population than covid would do just over a century later. It is believed that the fact that battalions of soldiers were moving around the world while staying in crowded tents also contributed to the explosive spread. Indeed, case fatality was much higher among those living in inner cities or in military training camps. Some think this could have partly contributed to the intriguing “W shape” of this pandemics, which had a huge toll on people in their 30s.

While the origin of the causing virus remained obscure for the better part of the century, we now know the pandemic was caused by a H1N1 influenza virus with genes of avian origin, and its genome was eventually sequenced - remember that influenza viruses have genomes made of RNA, much more prone to degradation than DNA, so obtaining samples were the viral genome was preserved was not free of challenges. And yet, key questions as to why this virus was so devastating are still unresolved. Controversy remains, for instance, over why this particular outbreak was linked to severe pneumonias or on the reason why healthy people in the prime of their lives were so heavily affected.

This is not the only pandemic that influenza viruses have caused, either. There have been two more, the most recent of which was the 2009 swine flu pandemic. Now, over a century after the 1918 influenza pandemic, the risk of spill-over of influenza from livestock to humans is growing, as researchers study molecular patterns that allow the virus to switch hosts and global health experts warn of the impact of environmental changes have on pandemic risk.

CONSENSUS

Is the flu vaccine effective?

100% affirmative via 8 experts

Some vaccines, such as the ones against measles or mumps, need just one or two doses during our childhood to protect us from the disease. However, in the case of influenza virus, jabs are needed every year for optimal protection. What does it mean? Is the flu vaccine really working?

Yes, the flu vaccine is effective. “They do not necessarily prevent everyone who has them from getting sick – but they do help to reduce the impact of infection and prevent deaths,” writes Prof Janet Daly from the University of Nottingham. The flu vaccine can protect 60%+ of the jabbed from getting sick, says Dr Chuanxi Fu from Zhejiang Chinese Medical University, who argues that “vaccination is the most effective weapon to prevent the flu.” “Besides the direct protection of the vaccinated, receiving the flu vaccine will probably also [indirectly] benefit their relatives, friends and colleagues,” he claims.

And yet, vaccine effectiveness is higher for some influenza strains than for others. For instance, a recent meta-analysis showed that the vaccine “tends to be better against influenza B (61%) and influenza A/H1N1 (54%) than against influenza A/H3N2 (33%),” says Dr Ryan Malosh from the University of Michigan. Many studies are currently being done to figure out why, he says. For this reason, flu jabs are typically a mix. In the words of Prof Jeff Kwong from the University of Toronto, “influenza vaccines contain 3 or 4 different strains: 1 H1N1 strain, 1 H3N2 strain, and 1 or 2 B strains.” This way, we can maximise our chances of getting protection.

Prof Mark Doherty from GSK writes that “there are thousands of different strains of flu circulating at any one time.” The good news, he says, is that the bulk of the disease across the population will be caused by only a handful of common strains. The not-so-good news is, “what’s common will change from year to year.” This is exactly “why you need a new vaccination every year – to cope with the changing influenza virus population,” he concludes. “The WHO and other scientists try and predict which strains of flu are going to be circulating in a given year, and they make the vaccine to defend against those viruses,” explains Dr Larisa Labzin from the University of Queensland.

CONSENSUS

Is a universal flu vaccine possible?

50% affirmative via 10 experts

Influenza kills hundreds of thousands every year, and is a medical and economical burden affecting the whole society. Unsurprisingly, health systems work hard to try and avoid people from suffering from it. Besides prevention strategies and antiviral drugs, as we have seen, the vaccine is a key weapon to achieve this. However, viruses continuously mutate and evolve. This is very much the case for the influenza virus. “The high mutation rates, and the ease of spread, have meant influenza remains a need to which researchers continue to respond,” explains Prof William Rawlinson from UNSW Sydney. That’s why people, and particularly those at greater risk, need to get a jab every year to catch up with the latest changes in the virus.

A universal vaccine that could provide lasting immunity for various flu seasons or perhaps even for life - regardless of how the virus mutates - would be a game changer. But how far are we from that, and is it even possible? “There are many researchers developing a ‘universal flu vaccine’, but I am not convinced that we will have an ideal (i.e. effective, tolerated and truly universal) vaccine in the near future,” writes Prof Daly.

An important challenge in developing a universal influenza vaccine is demonstrating that it will protect against all strains all the time, according to Dr Marc André D’Aoust from Medicago. “That demonstration requires lengthy clinical studies which will prevent the regulatory approval of an universal for several years,” says Dr D’Aoust. He remains optimistic, however. “With the progress of recombinant vaccine technologies, we can expect vaccines providing broader protection to different strains or vaccines that can be administered every 2-5 years to come to market in the foreseeable future,” he explains.

That said, many experts don’t think an universal vaccine will be developed in the short term. With this in mind, it “is a big mistake to put all the funding to this development alone,” argues Dr Larissa Rudenko from MIT. In her view, “more research on the improvement of existing vaccines is urgently needed.” In a view shared by other experts, she argues that, in fact, a universal vaccine against the flu may not even be needed. “The adjuvanted inactivated and live attenuated influenza vaccines are cross-reactive enough by themselves,” she explains, so we just need to work on their “optimization to make them more efficacious and cross-protective.”

CONSENSUS

Does influenza peak in winter just because it’s colder?

83% uncertain via 6 experts

Winter is undoubtedly peak season for influenza transmission, and that has knock-on effects on hospitalizations and deaths across the world, which increase way above summer rates during the winter months. “Winter seasons often coincide with respiratory virus seasons in general—not just influenza, but other respiratory viruses like rhinovirus, adenovirus, and respiratory syncytial virus,” explains Dr Maria Sundaram from the Marshfield Clinic Research Institute. That might be why some of us see going out in the cold as a risky business. Is it really cold temperatures that make us more vulnerable to respiratory illnesses, though?

The truth is, we don’t really know. Dr Stephen Kissler from Harvard University argues that “if there is a direct link between influenza and the weather, it probably has more to do with humidity than temperature.” Influenza can thrive better in the air when humidity drops, he explains, which usually happens at low temperatures. Prof Patricia Foster from Bloomington University in Indiana agrees: “there is good evidence that the flu virus survives and transmits infection better through the air when the humidity is low, which, in temperate regions, happens both outside and inside in the winter,” she writes. “In addition, when the humidity is low people’s airways dry out and that can increase susceptibility to the virus,” she adds.

It might partly come down to how cold temperatures affect behaviour as well, as we spend more time indoors during winter months. According to Prof Anne Moore from University College Cork, “due to the cold weather people congregate more indoors, in closer surroundings with less ventilation.” This “density” allows better transmission of the virus, she explains.

The jury is still out on this, however. “We do still see flu spread in tropical regions of the globe, so this can't be the whole story,” admits Dr Kissler. Other experts we asked point to lower levels of vitamin D or melatonin during winter as additional factors that could also contribute to winter spikes of influenza.

CONSENSUS

Can influenza spread between species?

100% affirmative via 6 experts

Influenza viruses can not only infect humans, of course. Because of their great diversity, some of these viruses can circulate in pigs, bats, horses, dogs or birds. Indeed, bird flu outbreaks have been in the news a lot in recent months as high infection levels are being recorded in Europe, and countries like the UK have reported their highest ever toll of avian influenza. The flu is one of the most deadly animal diseases, as it turns out, and can kill up to 90% of infected chicken. While influenza didn't affect wild birds in the past, when the H5N1 strain emerged, spillover from poultry outbreaks meant these birds - including migratory species - could become infected as well. This can set a vicious circle where the virus mutates in packed chicken or turkey farms, is spread by migratory birds and could eventually be passed on to us.

The question is, can influenza spread from one species to another? Absolutely, say the experts. For many, this calls for a “one-health” approach that considers our relationship with other species. According to Prof Ian Frazer from the University of Queensland, birds “are a major vector for spreading the flu viruses that make humans sick, and pigs are a common intermediary between birds and humans, allowing the flu viruses to adapt to infecting mammals.”

There have been episodes where a jump to humans has happened, explains Prof Foster, such as the 1968 Hong Kong flu pandemic (caused by a jump from birds) and the 2009 swine flu pandemic (caused by a jump from pigs). “This mixing up of the different strains in animals and humans allows genetic exchanges among the viruses, producing new, potentially dangerous, variants,” she warns.

Are we breeding the next pandemic? “Currently several avian influenza A strains that have already infected some humans are being closely monitored by world health organisations for their potential to cause a new pandemic,” explains Prof Foster. However, she also urges calm: “a pandemic will only erupt if one of the variants acquires the ability to efficiently transmit from person to person.”

Quick Answers

• Does Vitamin C help with the flu? Not much evidence at all that it can help against flu symptoms. A lot more has been written about whether it helps with colds, but even then experts are split.

• Does zinc help against the flu? A recent study found that over-the-counter zinc supplements are associated with fewer upper respiratory infections. That said, the effect was modest (1 infection avoided for every 20), the strength of the evidence was poor, and zinc might come with side effects.

• Is ‘flurona’ a new threat? No. This made-up word was all over the news a few weeks ago following a confirmed case of a flu-COVID co-infection. However, these co-infections are not new, and over 80 had already been reported so far.

TOP ANSWER

Can we prevent the flu?

Yes, partially. Vaccines help to reduce the spread of flu, but their main purpose is to reduce the severity of influenza illness, making it less likely that people with flu will need medical attention. Our experience with COVID-19 has also shown that non-pharmaceutical interventions like masking and physical distancing can almost completely suppress the spread of flu; this is probably why we didn't see much flu spread at all in the winter of 2020. While we don't want to have such severe restrictions every year to eliminate the spread of the flu, this still provides good evidence that more manageable, intermediate changes to our behavior could go a long way toward reducing influenza cases.

Dr Stephen Kissler from Harvard University

Takeaways

• Influenza poses a threat to societies across the globe. It usually gives you fever, sore throat and aches, but it can be dangerous or even deadly for some.

• Jabs (developed against a mix of the strains expected to dominate) reduce serious illness and deaths. Antivirals and non-pharmaceutical measures, like mask wearing if you have symptoms, can also help us tackle spikes.

• Influenza viruses mutate - a lot. Researchers are working on a universal flu vaccine so we don’t have to change the recipe and get people jabbed every year, but we are not there yet. That said, vaccines providing broader coverage are being developed.

• The jury is still out on exactly why there’s a winter spike of influenza. Low temperature and humidity enhance viral transmission, but us spending more time in less ventilated indoor spaces is also likely to contribute.

• Influenza can affect other species too, which encourages a “one-health” approach to deal with emerging infectious diseases. It has jumped to humans in the past, so the concern is whether it will spread between humans following animal to human transmission.

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All content is general in nature and educational information only. Remember to always talk to your healthcare professional on questions regarding your health - they are your best source of evidence. 

We face multiple decisions a day: What should I have for breakfast? What’s the best route to get to work? Which project should I prioritise today? Some decisions we face have high stakes, such as choosing a treatment for a patient or making a financial investment.

As humans, our ability to make decisions can be limited by biases and irrational thinking, so could we turn to algorithms to improve our decision making? We asked 6 experts in computer science, mathematics, and artificial intelligence (AI), ‘Do algorithms outperform us at decision making?’, here is what they said…

EXPERT CONSENSUS

Do algorithms outperform us at decision making?

5 out of 6 experts say ‘yes’

What is an algorithm?

An algorithm is simply a set of rules or calculations which takes input information and gives you an output. There are three major components to an algorithm:

1. The input data (e.g. the words ‘cake’, ‘apple’ and ‘banana’)

2. A process or calculation performed on this input data (e.g. sorting by alphabetical order)

3. The output data (e.g. the words in the order ‘apple’, ‘banana’, ‘cake’)

What are algorithms used for?

Algorithms are central to computer programming and data processing. They allow for information on the internet to be organised and accessible, and prioritise which hits come up first in search engines and on social media. Algorithms are not just confined to computer science but used in many fields, such as in medical settings to assist diagnoses or in the financial world to make economic forecasts.

Algorithms are increasingly being used to assist or, in some cases such as self-driving cars, completely remove the need for human involvement. Their usage permeates every aspect of our lives, from matching us with a potential partner on a dating app to planning our route to work.

Do algorithms outperform us at decision making?

Professor Scott Fahlman, an expert in computer science and AI from Carnegie Mellon University in the USA, says “In many domains, yes. For example, chess is a decision-making process, and AI-based systems can now beat the world champion.” The AI algorithm Deep Blue beat the world chess champion Garry Kasparov in 1997.

Dr David Tuffley, an expert in software science from Griffith University in Australia, highlights a caveat, saying “A well written algorithm does have the potential to outperform the notoriously quirky and inconsistent decision making that many humans perform. But it really depends on how well it was written by a human in the first place. They just do what they are told to do.”

Professor Mark Lee, an expert in computer science from Aberystwyth University in Wales, says “Consider programs that play games like chess or Go. These AI systems have now reached grandmaster level and have beaten the world's best human players. The search algorithms used in chess can analyse millions of possible moves in seconds and this allows them to see much further ahead in the game than humans can manage. This produces excellent decisions and many game playing programs can now learn to play a game from scratch and quickly become champion players.”

Are there situations where humans make better decisions than algorithms?

Professor Lee says “games are a very constrained kind of problem. In a board game everything is well defined and consistent – nothing else happens other than pieces are moved! In the real world, in our human environment, there are all kinds of problems for algorithms to overcome.”

He goes on to say “Just deciding where to take a holiday, for example, can be influenced by weather forecasts, geographic choices, travel convenience, personal preferences, interactions with family and others, calculations of acceptable budgets of time and cost, etc. These are not straightforward yes or no issues, unlike making a move in chess, but involve uncertainty, missing information, and value judgements. Algorithms that attempt to replace general human decision making have not been successful. AI research is working in many areas that help us to make decisions, perhaps the most useful is in providing relevant information, but the subtly of the human mind still beats machines in many ways. So, yes, algorithms can massively outperform humans, but only in certain limited contexts and restricted applications.”

Professor Fahlman agrees, saying “Current AI systems cannot yet match human abilities where broad, common-sense knowledge is required, or when dealing with unpredictable, complicated humans.”

Professor Kay Kirkpatrick, an expert in mathematics and AI from Illinois University in the USA, highlights something humans have that algorithms don’t: emotions. She says “It’s recently becoming well understood in cognitive science that emotions can help humans make decisions well and quickly, and there’s nothing comparable to this in algorithms so far.”

The takeaway:

Algorithms can outperform human decision making, but currently only in certain contexts.

May the facts be with you!

Eva

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According to the World Health Organisation (WHO), air pollution is one of the greatest environmental risks to health and in 2019, 99% of the world’s population lived in places where the WHO air quality guidelines were not met.

Air pollution is known to be linked to lung disorders, but could it also harm our brains? We asked 6 experts in epidemiology, biostatistics and neurology, ‘Does air pollution cause Alzheimer's disease?’, this is what they said…

EXPERT CONSENSUS

Does air pollution cause Alzheimer's disease?

4 out of 6 experts says ‘likely’

What is Alzheimer’s disease?

Alzheimer's disease is a brain disorder that causes a gradual decline in cognitive function. Alzheimer’s disease is the most common form of dementia, an umbrella term which refers to memory loss and cognitive decline. Over 55 million people worldwide have dementia, and 60-70% of those people have Alzheimer’s disease.

What is air pollution and where does it come from?

Air pollution is the chemicals or particles in the air that can harm plants and animals (including humans). Air pollution can come from human sources such as emissions from factories, cars or planes, or natural sources such as wildfires or volcanos. Air pollution can be worsened by heat or mountains which prevent air movement.

Dr Eirini Dimakakou, an expert in epidemiology and biostatistics from Heriot Watt University in Scotland, says “Particulate matter (PM), also known as particulate air pollution, is a complex mixture of extremely small particles and liquid droplets that are in the air of our cities. Once these particles are inhaled, they can cause serious health effects. Particles that are very small in diameter cause the greatest problems, because they can get very deep into the lungs, and they may even get into the bloodstream or the brain. Particulate matter comes from both human and natural sources. Soot from diesel vehicles, smoke from fires and wind-blown dust are all sources of airborne particulate matter.”

What are the dangers of air pollution?

Dr Dimakakou, says “Exposure to air pollution is a particular concern to the public. In Britain, the 1952 ‘London Smog’ heightened public awareness of the problem because of the increased mortality and morbidity reported soon after the event.” The ‘Great Smog of London’ was caused by a combination of people burning coal in their homes to keep warm and smog-forming weather conditions, and it was estimated to result in the death of at least 4,000 people.

Dr Dimakakou says “It is now widely accepted that exposure to air pollution may cause or exacerbate allergic respiratory diseases (e.g., asthma), chronic obstructive pulmonary disease, pneumonia, lung cancer and cardiovascular disease. More recently, evidence has emerged from epidemiological and experimental laboratory studies that long-term exposure to particulate air pollution may be associated with dementia.”

Professor Paul Ernsberger, an expert in pharmacology from Case Western Reserve University in the USA, explains how air pollution can affect our health, saying “Very small particles can enter the blood stream within the alveoli of the lung. From there they can reach the brain and other organs. Rates of lung, heart and neurological diseases can be linked to exposure to fine particulates smaller than 2.5 microns in diameter.”

Does air pollution cause Alzheimer's disease?

Dr Tia Louise Cummins, an expert in neuroscience from the Florey Institute of Neuroscience and Mental Health in Australia, says “Scientists are still unsure of the exact cause(s) of Alzheimer's, however it is likely that a number of factors are involved. Air pollution may be associated with Alzheimer's, but it is unlikely that it is the ‘cause’. Many lifestyle and medical variables are associated with Alzheimers, but we can not deduce the finite cause just yet.”

Dr Tim Wilkinson, an expert in neurology and Alzheimer’s disease from Edinburgh University in Scotland, highlights a review paper that examined the results of 9 research articles looking at the relationship between air pollution and brain health. He summarises the conclusions of the review as  

• “There is now ample evidence that links air pollution to poor brain health

• We don't understand when in the life course air pollution has the most impact (i.e. is it worse if exposed to air pollution in childhood, midlife etc)

• We don't understand whether it affects one particular subtype of dementia (e.g. Alzheimer's disease, vascular dementia) compared to others.”

Dr Dimakakou says “Human epidemiological evidence suggests that long-term exposure to fine particulate air pollution may be a risk factor for neurodegenerative diseases. The mechanisms underlying this are currently unknown, but it may involve the particles moving from the inhaled air to the brain or the release of inflammatory chemicals from the lung, which may indirectly cause damage in the brain.”

Dr Dimakakou goes on to say that “It is not absolutely clear whether particulate air pollution causes dementia, although exposure to air pollution may contribute to the initiation of disease or accelerate disease development. Is particulate air pollution an important cause or just another cause?  It’s known that small air pollution particles can enter the brain and the research shows a fairly consistent evidence of a link between air pollution and neurodegenerative diseases, but just not quite sufficient to provide unequivocal scientific proof. There are so many questions still unanswered, which definitely suggests a need for further research in this field.”

Professor Ying Zhang, an expert in epidemiology from Sydney University in Australia, summarises by saying that air pollution “may not be a direct cause of Alzheimer's disease but an epidemiological risk factor that could contribute to the development of the disease.”

The takeaway:

Air pollution may be linked to Alzheimer’s disease, but more research is needed to confirm this.

May the facts be with you!

Eva

Can we help prevent Alzheimer's with diet?

Learn more about the Alzheimer’s disease with our deep-diving review.

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The alarm starts beeping. You turn it off. You stretch. You check your phone. You jump in the shower. You get dressed. You rush to the kitchen. You make yourself a cup of your hot drink of choice. And so on. Habits are such a key element in our lives as certain behaviours become automatic.

How do we make doing exercise or eating healthy habitual and automatic? What about getting rid of bad habits, like texting while driving or or binge eating late at night? It's very hard for us to shape our habits and we struggle to keep New Years Resolutions.

We asked 20 neuroscientists and habit experts to share the facts on everything relating to Habits. How do habits form? Are they important? Can we break bad habits? Do habit-based interventions work for weight-loss?

Here's what we found.

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Meta-Index

43%: percentage of our actions that are done everyday in the same context.

40%: people who give up on their New Year’s resolutions by June.

20%: adults in the world who smoke tobacco.

84%: increase in successfully quitting tobacco when intensive advice is received.

20%: people who achieve long-term weight loss after a diet.

60: million people in the US who are members of a fitness center or health club.

2: average time in months needed for new habits to peak.

BACKGROUND

What are habits?

Psychologist Dr Benjamin Gardner from King's College London writes that habits "are actions that proceed automatically due to learned context-action associations which are activated when people are exposed to the context." In other words, they are actions we do without thinking because we’ve done them in similar circumstances before. For example, going into a movie theatre may non-consciously activate an association between the movie theatre and eating popcorn, such that people experience an urge to eat popcorn when they enter the movie theatre says Dr Gardner.

The three-point seat belt was invented in the late 1800's, but drivers fiercely opposed it. Now, almost all of us in the US buckle up out of habit. Research has shown that wearing a seat belt reduces the risk of serious injury by half, but it was government regulations and car beeps that added friction to not doing so. As a result, 90% of people have formed a habit of using seat belts.

Habits are not universal though and very much depend on context: just 2 in 10 drivers use seat belts in India, for example. Face masks are a great example when it comes to cultural differences. People in Japan and other Asian countries have been wearing surgical masks in public for decades, even before the COVID-19 pandemic. Every year, mass wearing of face coverings becomes habitual with the start of the flu season.

So where did habits come from?

CONSENSUS

Did habit formation serve a function in evolution?

100% Affirmative via 6 experts

Specific habits have been recorded in a number of vertebrates (including humans, dogs, whales or geese). Samuel Nordlii from Indiana University, writes that all vertebrates can form habits and the brain circuits involved are retained across different species suggesting that formation of habits certainly served a role in evolution.

Habits become almost reflex, instinctive behaviours. Why would this be helpful for us as a species? We can think of them as a mechanism to bypass the decision-making step in contexts we are presented with repeatedly, and where we end up making the same decision every time. This way, we can ‘lock in’ the behaviours that we do so often and free up our attention or memory for tasks that we are not so familiar with.

Dr Wendy Wood, an expert in behavioural science from University of Southern California, agrees. If we get a reward doing a certain action in a context that keeps coming about, she says, evolution would create a shortcut to automate such response. Habit formation is a gradual process whereby your actions change the wiring of our brain. Every time we act in the same way, the habit strengthens. Over time, it becomes more automatic and is stored in our procedural memory, Wood explains. This is a form of memory which is no longer linked to consciousness, does not involve decision making and is less susceptible to changes.

This is why, according to Professor Klaus Rothermund from the University of Jena, habits almost certainly serve an evolutionary function: not because of the specific actions themselves, but because of the memory and learning processes that underlie them.

CONSENSUS

Are habits linked to the environment?

100% Affirmative via 8 experts

Forming a new habit means turning a cognitively demanding behaviour (which initially requires attention, intention, decision-making and planning) into a routine. According to our experts, the environment plays a key role here. Habit formation needs a stable context that favours our action, argues Dr Domenico Maisto, an expert in neuroscience from the National Research Council of Italy.

According to psychology expert Benjamin Gardner from King’s College London, it is the environment that ultimately triggers habitual actions. In environments where we have repeatedly done the action in the past, the habit will have formed so that we have learned to associate that environment to our action. Take popcorn as an example. Many of us ‘instinctively’ get popcorn when we go to the cinema, even if we are not particularly big fans in other contexts. So do we really like them, or is it out of habit?

A 2014 study placed either apples or popcorn near participants and looked at what they ate. Perhaps unsurprisingly, those with popcorn on hand ate more of that. However, those with apples placed near them ate more apples than popcorn, and so consumed much fewer calories. This is a great example that setting up a context that reduces friction for our preferred choice or action (here, eating apples) can be helpful.

Just like the environment which we have associated with a certain habitual behaviour is crucial, changing it can have clear effects. In another study, behavioral changes (such as stopping to use single-use bags) were found to be more successful among people who had recently moved house, showing that changing the context can help form new habits or indeed leave old ones behind — those we had learned to associate to our previous environment.

CONSENSUS

Is it harder to break a bad habit than form a good one?

71% Affirmative via 7 experts

Breaking old habits can be more challenging than forming new habits say most experts. "It is always easier to form a habit than to break one, irrespective of whether these habits are “good” or “bad” writes Professor Klaus Rothermund from the University of Jena. The reason is there is more conscious effort in breaking bad habits.

"Forming new habits requires creating a responding action to an environmental trigger" writes Dr Gina Cleo from Habit Change Institute. "For example when I’m having breakfast, I will eat a piece of fruit. On the other hand, breaking old habits requires preventing an automatic reaction from taking place (e.g., when I go to the cinema, I will not eat popcorn, or I will eat peanuts instead of popcorn). Habits are actions which are automatically responding to a triggering cue. Therefore, habitual action can be impulsive, subconscious and automatic, and we are generally not mindful of habitual performance" writes Dr Cleo.

Habits are also generally more likely to form when rewards are immediate writes Dr Rachel Smith from Texas A&M. Ice cream for an example is an immediate reward, whereas going to the gym and flossing are more often associated with long-term gratification. Many "bad" habits also involve negative reinforcement, when a behavior results in reducing a negative outcome (as opposed to increasing a positive outcome). For example, biting your nails might reduce your temporary anxiety, so the behavior is reinforced by feeling better or being distracted. For all these reasons, undesired behaviors often are the ones that are more likely to become habitual.

"Breaking a pre-existing habit therefore, requires deliberative and conscious control over automatic cue-response associations writes Dr Cleo. "This is certainly achievable" she writes "when we are highly motivated, however when we are stressed, tired, experience emotional exhaustion, cognitive overload or negative emotions, the necessary conscious control required to break a habit becomes extremely difficult to sustain. Although motivation and conscious effort are also required to form new habits, we can use external reminders to nudge us towards performing the habit, which reduces the need for action planning and prospective memory".

Quick Answers

How to build a new habit? Plan your desired action for a time and place which you encounter frequently, and place cues within your daily routine.

How can we break a habit? Avoiding the environments that trigger it, consciously refraining from performing the triggered action, or unlearning the association (which is probably the hardest).

Why do ‘bad’ habits stick so easily? They typically come with immediate gratification, while ‘good’ habits usually carry delayed reward (think of ice cream vs workout!)

Are ‘bad’ habits really bad though? Only for present-day standards. Eating junk food is arguably a bad habit today, but would have provided quick calories to our ancestors.

Do habit-based interventions for weight-loss work? Yes. Recent research suggests they are "2.4 times more likely to achieve clinically beneficial weight loss".

Is addiction a habit? Definitely not. Addiction is not a habit although habit may contribute to addiction.

TOP ANSWER

Are there methods to break habits?

Yes! Habits are malleable throughout our entire life and with enough motivation, self-regulation and persistence, can be modified, weakened or ‘broken’.

Habits are triggered by exposure to environmental cues which activate learned cue-routine associations. Breaking a habit therefore, requires inhibiting or avoiding these established cue-routine behavioural responses. There are two widely known methods to ‘break’ a habit:

1 - Creating a counter-habitual implementation intention where we reprogram an alternative behavioural response when encountering the existing habit-trigger.

For example, if an individual is in the habit of drinking wine after work to unwind, they could replace the wine with an alternative behaviour that will still help them to unwind (e.g., a cup of herbal tea, hot shower, soft music, meditation, deep breathing, stretching, etc).

Another counter-habitual strategy includes ignoring the critical cue associated with the habitual response. For example, ‘when I crave sugar, I will ignore my urge to eat something sweet’.

These strategies create new cue-routine associations that directly compete with the existing habit; with consistency, the new responses have the potential to override and diminish the old habits.

It is worth noting that implementation intentions weaken the past cue-routine associations and reduce automaticity but are effective only when they are supported by strong goal-intentions or desires.

2 - Avoiding the environments that trigger the habit are an effective strategy to breaking habits. However, some environments are difficult to avoid, for example, if you are triggered to smoke a cigarette when you get to work, it may not be possible to avoid going to work. In cases where triggering environments are possible to avoid, this should be the preferred strategy for breaking habits as it can be easier compared with creating counter-habitual responses.

It should be noted that habits vary in strength on a continuum, so that they may be more or less habitual, or automatic. It is not entirely accurate to say a habit is ‘broken’, as it is more likely weaker in strength on the habit continuum.

Dr Gina Cleo

A Habit Expert from Bond University

Takeaways

• The brain loves repetition, so habits are part of our normal brain functioning.

• Habits are linked to a type of memory that doesn’t involve decision-making. That’s why they feel automatic.

• If there’s something you want to stop doing, change the environment or cue. If not, create a counter-habit (e.g. if you want to stop having a wine after work, start replacing it using something else, a cup of herbal tea, hot shower, soft music, meditation, deep breathing).

• To form a new habit, reduce friction. Make sure there’s healthy food in your fridge and sportswear in your wardrobe for example.

• Habits take time to become automatic, which will vary across people. Reward yourself and don’t despair!

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All content is general in nature and educational information only. Remember to always talk to your healthcare professional on questions regarding your health - they are your best source of evidence. 

The vape industry has exploded in the last few years. Walking down the street you might be able to smell that someone is vaping close by, this means you are inhaling their second-hand vapour or aerosol. Although we have a pretty good understanding of the health impacts of second-hand smoke from cigarettes, the potential effects of second-hand vapour are less clear.

What is in second-hand vapour? If chemicals such as nicotine are found in second-hand vapour, are they at high enough levels to do damage to people close by? We asked 5 experts in smoking, chemistry, cell biology and public health, ‘Is a harmful level of nicotine exhaled when vaping?’, here is what they said…

EXPERT CONSENSUS

Is a harmful level of nicotine exhaled when vaping?

60% uncertain

What is vaping?

‘Vapes’ or ‘e-cigarettes’ are battery-powered devices that heat up liquids to create an aerosol that you inhale. The vaping and e-cigarette industry was valued at over 17 billion US dollars in 2021 and about 82 million people regularly vaped in 2021.

Here we will refer to people who regularly vape as ‘vapers’ or ‘primary vapers’, and those who inhale what vapers exhale as ‘secondary vapers’. The gas that is exhaled when vaping is called ‘secondhand vapour/aerosol’.  

Is nicotine exhaled when vaping?

Professor Mathieu Morissette, an expert in cell biology from Laval University in Canada, says “Vapes do exhale nicotine and it can remain in suspension in the room and be detected and quantified”. Dr Neal Benowitz, an expert in smoking and medicine from California University in the USA, says “Nicotine that is exhaled quickly leaves particles and enters the environment as a gas, then deposits on surfaces. Nicotine can be found on surfaces in homes and business where people vape. Non-nicotine users who lives with vapers have measurable but low levels of cotinine (the main metabolite of nicotine) in their blood.”

It is not clear exactly how much nicotine is exhaled due to the many variables involved. Dr Benowitz says “The amount of nicotine varies tremendously by the type of device and the behaviour of the vaper. High power devices generate large amounts of aerosol, much of which may be exhaled, such as in cloud chasing. Low power devices generate small amounts of aerosol, and very little is exhaled.” Professor Morissette adds that “Variables affecting the amount of nicotine in the air are/can be severals: nicotine concentration in the e-liquid (from 0 to >30mg/ml); vaping intensity; room size; ventilation; distance between primary and secondary vaper; etc”

Is the amount of nicotine in vapour harmful?

Dr Morissette says “Can it be harmful? Acutely, very unlikely. However, chronic nicotine exposure does have adverse effects, especially in young individuals. We also have to consider that secondary vapers could, over time, develop low grade nicotine addiction that could make them more susceptible to start vaping or smoking. However, this remains a hypothesis.”

Professor Lynne Dawkins, an expert in public health and addiction from London South Bank University in the UK, says “Detectable levels of nicotine have been found in e-cigarette vapour generated in the laboratory but these were 10 times lower than levels measured in tobacco smoke (3.32 μg /m3 compared with 31.6 μg /m3). Moreover, under normal usage conditions, the user would inhale most of this vapour, so exhaled levels would be even lower. So, using an e-cigarette in an indoor environment may expose others to low levels of nicotine but this is unlikely to be harmful.”

Is there anything else in secondhand vapour that could be harmful?

Professor Dawkins says “Nicotine actually carries minimal health risks - it's the thousands of other chemicals in tobacco smoke [from cigarettes] that are responsible for almost all the harms. There is clear evidence that second hand smoke is harmful but this is not because of the nicotine.”

Perhaps the secondhand vapour from vapes could also be dangerous, but not because of nicotine. Other things found in secondhand aerosols from vapes include heavy metals, cancer-causing compounds such as benzene and fine particles.

Although these chemicals are dangerous when inhaled at high doses, secondhand vapour only contains very small amounts. Professor Dawkins says that “In relation to e-cigarette vapour, in a recent evidence review of e-cigarettes commissioned by Public Health England it was concluded that there is no evidence that e-cigarette vapour is harmful to bystanders.”

Is there uncertainty around how harmful secondhand vapour is?

Dr Rebecca Williams, an expert in public health from the University of North Carolina at Chapel Hill in the USA, believes that “There is insufficient research evidence to answer this question at this time, particularly in a general sense without context (number of people vaping, size of enclosed/unenclosed space, proximity to non-vaping people, how you define 'harmful level of nicotine', etc).” She says “I suspect that as more and more research on this topic is published, the evidence for secondhand e-cigarette vapour being a health risk to non-vapers will grow substantially.”

The takeaway:

Current research suggests that second-hand vapour does not contain a harmful level of nicotine, but more research is needed.  

May the facts be with you!

Eva

Is it harder to break a bad habit than form a good one?

Learn more about the habits with our deep-diving review.

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With thousands of questions answered by our verified expert community of researchers, professors and doctors - I thought you’d like to know the questions that are the most google searched on Metafact.

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QUESTION #1:

Is drinking 1/2 bottle of wine each night harmful to health?

EXPERT CONSENSUS: 100% Yes via 4 experts in alcohol use

Drinking heavily increases the risk of serious illnesses such as cancers and liver disease, as well as injuries. The degree of risk varies according to specific diseases. While the individual risk may be small, in a population of 1000 people, there would be a significant increase in the rates of different diseases and injuries compared to drinking less or none at all.

Read what the experts say here.

QUESTION #2:

Is 400mg of caffeine a day a safe threshold?

EXPERT CONSENSUS: 100% Yes from 6 experts

The European Food Safety Authority has concluded that for the general population, 400 mg per day is the safe limit for caffeine intake. For others, the maximal dosage advised in one sitting is 200 mg (2 cups coffee) and 3 mg/kg for adolescents and children. Pregnant and nursing women should not exceed 200 mg daily.

Read what the experts say here.

QUESTION #3:

Does IQ decrease with age?

EXPERT CONSENSUS: Uncertain via 5 Intelligence experts

Approximately 67 percent of intelligence is influenced by genetic factors and 10-12 percent is influenced by early life factors. These factors generally do not change, so most of our intelligence does not decline with age. However, negative environmental stimuli and serious diseases can cause decrease in intelligence.

Intelligence is usually measured by a set of tests. Your intelligence will be the average of your scores compared to how well other people do, and as you age, different skills change at different rates. Generally, cognitive skills relying on crystalized knowledge increase or are resistant until late sixties; however, speed can decline. Overall intelligence can remain similar with age.

Read what the experts say here.

QUESTION #4:

EXPERT CONSENSUS: 100% Yes via 5 animal experts

Are Hyenas more closely related to cats than dogs?

Batman is correct! Contrary to appearances, hyenas are more closely related to cats than to dogs. The four species of hyena belong to the family Hyaenidae and the suborder Feliformia, while dogs, foxes and wolves belong to the order Carnivora but the suborder Caniformia.

Read what the experts say here.

QUESTION #5:

Are the stars we see in the sky actually 'dead'?

EXPERT CONSENSUS: 88% No from 8 Astrophysicists

Most of the stars you can see with the naked eye are still alive, as they are no more than 10,000 light years away. Most stars live for 1 billion years, so it's unlikely that any particular star died during the past 10,000 years. Even out of the 6,000 stars visible without a telescope, it's unlikely that any have died by the time we see them.

Read what the experts say here.

May the facts be with you!

Ben

Is the microbiome a human organ?

Learn more about the microbiome with our deep-diving review.

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Whether it is to nuts, animals or pollen, most of us have or know someone with an allergy. I personally suffer from hay fever, which is becoming a nuisance now in the British springtime. I’m not alone – its estimated that 10-30% of the world’s population has hay fever. Food allergies can be even more problematic, and in the US the number of children who have a food allergy has risen 50% from 1997 to 2011.

Genetics explains only around 10-40% of a person’s risk to develop allergies, so the remaining percentage lies with our environment. The hygiene hypothesis states that childhood’s lack of exposure to certain microbes could increase their chances of developing allergies. To find out more about this, we asked 5 experts in immunology, allergology and medicine, ‘Is there clear evidence for the hygiene hypothesis?’, this is what they said…

EXPERT CONSENSUS

Is there clear evidence for the hygiene hypothesis?

5 of 5 experts say likely

What is the hygiene hypothesis?

Professor Marie-Claire Arrieta, an expert in microbiology and immunology from Calgary University in the USA, says “The Hygiene Hypothesis was born from work made by Dr. David Strachan, who observed that younger siblings were less susceptible to eczema and asthma, and proposed that this was a result of increased transmission of infectious agents via unhygienic practices within a household.”

Dr Cosby Stone, an expert in immunology and allergology from Vanderbilt University in the USA, says “The central tenet of the hygiene hypothesis is that we have gone a bit too far and inadvertently killed off our good bacteria along with the bad. As our society progressed from one that was chronically burdened with infectious diseases caused by poor sanitation, the thinking goes, we reduced our exposures to the things that gave our immune system an appropriate training and tolerance. Historically, our totally rational fear of dying from a cholera epidemic led to sewage and water management, but may have kicked off the allergy epidemic.”

What conditions are linked to the hygiene hypothesis?

The most well-known condition linked to the hygiene hypothesis are allergies. Allergies are when the body reacts to something that is normally harmless. Apart from allergies, the hygiene hypothesis is also said to be linked to autoimmune diseases.

Professor Graham Rook, an expert in immunology from University College London in the UK, says “What we see in modern, particularly urban, communities is an increase in disorders where the immune system’s control mechanisms are failing so that it attacks things it should ignore. For example, in autoimmune diseases like multiple sclerosis our immune systems are attacking our own tissues. Similarly, our immune systems attack harmless molecules in the air, or in food (allergies) or they attack the contents of our guts which contributes to inflammatory bowel diseases.”

How can being ‘too clean’ negatively affect our immune system?

Professor Rook says “The vertebrate immune system has co-evolved, over about 500 million years, with an increasingly complex gut microbiota (the community of mostly symbiotic organisms that live in and on us, particularly in our guts). The microbiota plays an essential role in driving the development and function of essentially all our organs (including the brain), but particularly the development of the immune system, and of the mechanisms that regulate it.

Similarly, our airways need exposure in early life, to microbial components from the natural environment that provide signals involved in setting up the appropriate background level of activity of the immune system, and above all, appropriate activity of anti-inflammatory regulatory mechanisms in those sites… In summary, the vertebrate immune system is a learning system like the brain, and without various microbial inputs that provide essential data it cannot function correctly.”

What is the evidence for the hygiene hypothesis?

Professor Robert Clark, an expert in immunology from Connecticut University in the USA, says “studies have demonstrated increased asthma in genetically similar populations in which one population farms in an old fashioned and ‘dirtier’ environment while the other population uses modern and ‘cleaner’ farming methods. The cleaner population had a significantly increased frequency of asthma, suggesting that exposure to bacterial products in the dirtier environment ‘educates’ and ‘acclimates’ and essentially calms the immune system to environmental and self-stimuli, - so there is less of an over-reponse to both environmental and self stimuli (and less asthma). In the ‘cleaner’ and more asthmatic environment, direct evidence was documented showing that the immune system over-reacts to such stimuli.”

Dr Stone adds that “Studies in mice have shown that inhaling certain molecules from soil-dwelling bacteria can set off a beneficial cascade promoting an immune system which focuses more on threats rather than nonthreats, such as allergens.”

Does this mean we should stop washing our hands?

Professor Rook says “The problem lies in the misleading term ‘Hygiene Hypothesis’. It is certain that our immune systems are malfunctioning because of diminished microbial exposures and diminished ‘microbial data input’, but it is increasingly clear that hygiene does not play a major role in causing this diminished exposure…. I emphasise that hygiene, particularly hand-washing, is entirely beneficial”

Professor Rook explains the major areas where the hygiene hypothesis comes into play, saying “caesarean deliveries and some inappropriate hygiene might inhibit transfer of maternal microbiota to the infant… The second most important factor is the overuse of antibiotics, particularly during pregnancy and in early life. Repeated courses of antibiotics increase the incidence of allergies, other inflammatory disorders, and obesity. The third factor is the bad Western diet. The biodiversity of the gut microbiota is maintained by a varied diet, and by fibre (plant cell walls) and plant polyphenols that nourish crucial beneficial microbial species, several of which help to drive the immunoregulatory pathways. A fourth factor is lack of exposure to the natural environment. Keeping a dog in the home partially compensates, because the dog brings the environment into the home. But walking and exercising in green spaces, and gardening are the best solutions.”

Professor Rook concludes that “Major lifestyle changes (diet, antibiotics, lack of exposure to the natural environment) are leading to defective education of our immune systems, and to disorders attributable to failing immunoregulation. We clearly need to rename the hygiene hypothesis. Recent suggestions include ‘Biodiversity hypothesis’ and ‘Old Friends Hypothesis’.”

Dr Stone adds that “Vaccinations appear to be a crucial exception to the rule of the hygiene hypothesis. They confer protection against diseases without any associated increase in the risk of allergic disease, likely because they, unlike antibiotics, are very specifically targeting only the worst disease-causing organisms.

The takeaway:

Increased allergy and autoimmune disease risk is linked to overuse of antibiotics, poor diet and lack of contact to natural environments, because these can prevent your body’s exposure to ‘good’ or benign bugs. Importantly, allergies are not linked to hygiene and health practices such as hand washing and vaccinations, and these are important to protect against infections.

May the facts be with you!

Eva

Is the microbiome a human organ?

Learn more about the microbiome with our deep-diving review.

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Fish oil has been widely reported to help against a myriad of ailments from ADHD to gut health. Fish oil has most often been reported to be good for your heart, defending against cardiovascular disease and heart attacks. Is the hype around fish oil warranted? We asked 5 experts in physiology, neurology and cardiology, ‘Is fish oil good for heart health?’, this is what they said…

EXPERT CONSENSUS

Is fish oil good for heart health?

4 of 5 experts say likely

What’s in fish oil?

Fish oil is found in the tissues of oily fish such as mackerel, salmon and tuna. Dr Theresa Larkin, an expert in physiology from Wollongong University in Australia, says “Fish oil contains long chain omega-3 polyunsaturated fatty acids, often just called omega-3 fatty acids.” Omega-3 fatty acids are molecules made of a hydrocarbon chain with a carboxylic acid group. There are two types of omega-3 fats found in fish oil: EPA and DHA.

What does omega-3 do to the body?

Professor Ludmila Belayev, an expert in neurology at the LSU Health Sciences Centre New Orleans in the USA, says “Your body needs omega-3 fatty acids for many functions. Omega-3 fatty acids are essential for good health.”

Dr Larkin adds that omega-3 fatty acids “can lower inflammation and have positive benefits on the health of our heart and blood vessels.” She explains that “The direct effects of fish oil on heart health are in the heart itself. When there are more omega-3 fatty acids in the membranes of the heart’s cells, these cells function better. Fish oil can lower a high heart rate and can also reduce the risk of irregular heart rhythms.” She adds that “The indirect benefits of omega-3 fatty acids on the heart are via their effects on the blood vessels and factors in the blood.  Fish oil can reduce triglycerides in the blood and prevent blood from clotting too much.  They also relax the muscles of the blood vessels.  These effects can reduce blood pressure and allow the heart to contract more efficiently and use less energy.”

What is the evidence that fish oil improves heart health?

There have been a range of studies on the effects of fish oil and omega-3 on heart health, with mixed results. These studies vary in many details such as the source of omega-3 they use (e.g. fish diet vs omega-3 supplements), the amount and duration of the omega-3 treatment, or whether the patients are healthy or have existing heart conditions. There are also other factors that can influence whether someone benefits from fish oil or not, such as their genetics and their normal diet.

Dr Jawahar Mehta, a cardiologist from Arkansas University in the USA, says “The basic research shows promising effect of fish oil on thrombus formation and on cellular injury. In some clinical trials in patients with very high triglyceride levels and previous cardiac events, the use of fish oil, especially high concentrations of EPA, looks very good.” Dr Mehta adds that “Unfortunately, the large number of trials on the use of fish oil in patients with heart disease do not reveal very promising results. This is true in both primary and secondary prevention trials.”

Dr Larkin says “People who consume higher levels of fish oil have a lower risk of heart disease and lower risk of death due to heart disease.”

How can you consume fish oil?

Professor Belayev says “Fish oil supplements might be helpful if you have high blood pressure, high triglycerides, and cholesterol or rheumatoid arthritis. Try getting high-quality fish oil produced from Norwegian Atlantic salmon, which includes 500 or 1000mg of docosahexaenoic acid (DHA).” The omega-3 supplements market size was valued at 5.6 billion US dollars in 2020.

You can also get omega-3 from fish directly, particularly oily fish such as mackerel, salmon, seabass and sardines. A strong correlation between fish consumption and improved heart health has been observed since the 1970s, so perhaps fish consumption is a better way to improve heart health, as compared to taking omega-3 supplements.  

The takeaway:

Fish oil may improve heart health, but there are other ways that are more effective at improving your heart health: exercise, balanced diet and reduced smoking and alcohol.

May the facts be with you!

Eva

Do multivitamins make you healthier?

Learn more about supplements with our deep-diving review.

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Dr Oliver Baumann, an assistant professor at Bond University in Australia recently wrote in a The Conversation article that “the brain accounts for about 20% of the body’s energy consumption, despite only representing 2% of its weight. That’s around 0.3 kilowatt hours (kWh) per day for an average adult, more than 100 times what the typical smartphone requires daily.” That’s a lot of energy!

Creatine is used as a supplement by athletes to improve energy supply to muscles. Considering the brain’s high energy demands, could creatine increase energy levels in this essential organ and therefore improve cognition? We asked 6 experts in neuroscience, exercise physiology and psychiatry ‘Does creatine improve cognition?’, here is what they said…

EXPERT CONSENSUS

Does creatine improve cognition?

3 of 6 experts are unsure

What is creatine?

Our bodies can make use of different stores of energy. When Usain Bolt runs his 100m race, the first couple of seconds after the starting gun his body is using a molecule called ATP. In the next two seconds, the ATP stores in his cells are replenished by another chemical called creatine. In the last five seconds of the race, Bolt’s body is running off a process called anaerobic respiration, which creates lactic acid, a by-product that causes muscle pain.

Creatine is a naturally-occurring, organic compound that is involved in maintaining a reservoir of the energy-carrying molecule ATP in our cells. Creatine is made in the kidneys and liver and can also be consumed from meat, fish or dietary supplements. Whilst most creatine is found in the muscles, Dr Justin Roberts, an expert in exercise physiology from Anglia Ruskin University in the UK, says “Around 5% of the body’s creatine is stored in other tissues including our brain.”

How might creatine boost cognition?

The most intuitive explanation is that creatine supplies more energy to the brain, and this would lead to improved cognition. Dr Xuansong Mao, an expert in exercise physiology from Virgina Tech in the USA, says that creatine “contributes to form ATP when energy demand increases, [but] this area of research still remains to be confirmed. Other possibilities could be that creatine supplementation improves cognitive function through activating certain molecular pathways, resulting in increased synaptogenesis in the brain.”

Does creatine improve cognition?

Dr Philip Dean, an expert in neuroscience and neuroimaging from Surrey University in the UK, says “There are mixed results from animal and human research in this area, with mixed supplements given (some containing other substances than creatine e.g. in sports supplements with sugars/proteins added), at mixed doses (much higher in animals) over mixed periods (high dose/short time; low dose/long time) in different populations (e.g. vegan/vegetarian) with mixed output variables (cognitive tasks, neuroimaging). Whether oral creatine supplementation increases creatine in the brain is still not certain.”

Professor Caroline Rae, an expert in neuroscience and biochemistry from Neuroscience Research Australia, says “appropriate supplementation with creatine has been shown to improve some cognitive tasks, such as those involving short term memory and fast processing. We showed this in vegetarians in 2003 but this result has now been reproduced by others in omnivores. It has also been suggested that older people may benefit more.”

Studying the effects of creatine on cognition is not straightforward. Dr Dean explains that creatine research “becomes trickier when looking at Phosphocreatine vs Creatine in the brain, and when accounting for the osmotic properties of creatine (water retention) which can affect data collected. Any relationship between cognition and creatine might be caused by increases in the body, other substances in the supplement or placebo effects. Properly powered and controlled studies are needed to understand potential mechanisms”

Dr Beny Lafer, an expert in psychiatry from Sao Paulo University in Brazil, concludes that “A few small studies suggest a potential benefit of Creatine on cognition but this needs to be further tested in large and controlled studies”

The takeaway:

Creatine may improve cognition but more research is needed to verify this.

May the facts be with you!

Eva

Does Vitamin C boost immune function?

Learn more about supplements with our deep-diving review.

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