‘We know little about the effect of diet on health. That’s why so much is written about it’. That is the title of a post in which I advocate the view put by John Ioannidis that remarkably little is known about the health effects if individual nutrients. That ignorance has given rise to a vast industry selling advice that has little evidence to support it.
The 2016 Conference of the so-called "College of Medicine" had the title "Food, the Forgotten Medicine". This post gives some background information about some of the speakers at this event. I’m sorry it appears to be too ad hominem, but the only way to judge the meeting is via the track record of the speakers.
Quite a lot has been written here about the "College of Medicine". It is the direct successor of the Prince of Wales’ late, unlamented, Foundation for Integrated Health. But unlike the latter, its name is disguises its promotion of quackery. Originally it was going to be called the “College of Integrated Health”, but that wasn’t sufficently deceptive so the name was dropped.
For the history of the organisation, see
The new “College of Medicine” arising from the ashes of the Prince’s Foundation for Integrated Health
Don’t be deceived. The new “College of Medicine” is a fraud and delusion
The College of Medicine is in the pocket of
Crapita Capita. Is Graeme Catto selling out?
The conference programme (download pdf) is a masterpiece of bait and switch. It is a mixture of very respectable people, and outright quacks. The former are invited to give legitimacy to the latter. The names may not be familiar to those who don’t follow the antics of the magic medicine community, so here is a bit of information about some of them.
The introduction to the meeting was by Michael Dixon and Catherine Zollman, both veterans of the Prince of Wales Foundation, and both devoted enthusiasts for magic medicne. Zollman even believes in the battiest of all forms of magic medicine, homeopathy (download pdf), for which she totally misrepresents the evidence. Zollman works now at the Penny Brohn centre in Bristol. She’s also linked to the "Portland Centre for integrative medicine" which is run by Elizabeth Thompson, another advocate of homeopathy. It came into being after NHS Bristol shut down the Bristol Homeopathic Hospital, on the very good grounds that it doesn’t work.
Now, like most magic medicine it is privatised. The Penny Brohn shop will sell you a wide range of expensive and useless "supplements". For example, Biocare Antioxidant capsules at £37 for 90. Biocare make several unjustified claims for their benefits. Among other unnecessary ingredients, they contain a very small amount of green tea. That’s a favourite of "health food addicts", and it was the subject of a recent paper that contains one of the daftest statistical solecisms I’ve ever encountered
"To protect against type II errors, no corrections were applied for multiple comparisons".
If you don’t understand that, try this paper.
The results are almost certainly false positives, despite the fact that it appeared in Lancet Neurology. It’s yet another example of broken peer review.
It’s been know for decades now that “antioxidant” is no more than a marketing term, There is no evidence of benefit and large doses can be harmful. This obviously doesn’t worry the College of Medicine.
Margaret Rayman was the next speaker. She’s a real nutritionist. Mixing the real with the crackpots is a standard bait and switch tactic.
Eleni Tsiompanou, came next. She runs yet another private "wellness" clinic, which makes all the usual exaggerated claims. She seems to have an obsession with Hippocrates (hint: medicine has moved on since then). Dr Eleni’s Joy Biscuits may or may not taste good, but their health-giving properties are make-believe.
Andrew Weil, from the University of Arizona
gave the keynote address. He’s described as "one of the world’s leading authorities on Nutrition and Health". That description alone is sufficient to show the fantasy land in which the College of Medicine exists. He’s a typical supplement salesman, presumably very rich. There is no excuse for not knowing about him. It was 1988 when Arnold Relman (who was editor of the New England Journal of Medicine) wrote A Trip to Stonesville: Some Notes on Andrew Weil, M.D..
“Like so many of the other gurus of alternative medicine, Weil is not bothered by logical contradictions in his argument, or encumbered by a need to search for objective evidence.”
This blog has mentioned his more recent activities, many times.
Alex Richardson, of Oxford Food and Behaviour Research (a charity, not part of the university) is an enthusiast for omega-3, a favourite of the supplement industry, She has published several papers that show little evidence of effectiveness. That looks entirely honest. On the other hand, their News section contains many links to the notorious supplement industry lobby site, Nutraingredients, one of the least reliable sources of information on the web (I get their newsletter, a constant source of hilarity and raised eyebrows). I find this worrying for someone who claims to be evidence-based. I’m told that her charity is funded largely by the supplement industry (though I can’t find any mention of that on the web site).
Stephen Devries was a new name to me. You can infer what he’s like from the fact that he has been endorsed byt Andrew Weil, and that his address is "Institute for Integrative Cardiology" ("Integrative" is the latest euphemism for quackery). Never trust any talk with a title that contains "The truth about". His was called "The scientific truth about fats and sugars," In a video, he claims that diet has been shown to reduce heart disease by 70%. which gives you a good idea of his ability to assess evidence. But the claim doubtless helps to sell his books.
Prof Tim Spector, of Kings College London, was next. As far as I know he’s a perfectly respectable scientist, albeit one with books to sell, But his talk is now online, and it was a bit like a born-again microbiome enthusiast. He seemed to be too impressed by the PREDIMED study, despite it’s statistical unsoundness, which was pointed out by Ioannidis. Little evidence was presented, though at least he was more sensible than the audience about the uselessness of multivitamin tablets.
Simon Mills talked on “Herbs and spices. Using Mother Nature’s pharmacy to maintain health and cure illness”. He’s a herbalist who has featured here many times. I can recommend especially his video about Hot and Cold herbs as a superb example of fantasy science.
Annie Anderson, is Professor of Public Health Nutrition and
Founder of the Scottish Cancer Prevention Network. She’s a respectable nutritionist and public health person, albeit with their customary disregard of problems of causality.
Patrick Holden is chair of the Sustainable Food Trust. He promotes "organic farming". Much though I dislike the cruelty of factory farms, the "organic" industry is largely a way of making food more expensive with no health benefits.
The Michael Pittilo 2016 Student Essay Prize was awarded after lunch. Pittilo has featured frequently on this blog as a result of his execrable promotion of quackery -see, in particular, A very bad report: gamma minus for the vice-chancellor.
Nutritional advice for patients with cancer. This discussion involved three people.
Professor Robert Thomas, Consultant Oncologist, Addenbrookes and Bedford Hospitals, Dr Clare Shaw, Consultant Dietitian, Royal Marsden Hospital and Dr Catherine Zollman, GP and Clinical Lead, Penny Brohn UK.
Robert Thomas came to my attention when I noticed that he, as a regular cancer consultant had spoken at a meeting of the quack charity, “YestoLife”. When I saw he was scheduled tp speak at another quack conference. After I’d written to him to point out the track records of some of the people at the meeting, he withdrew from one of them. See The exploitation of cancer patients is wicked. Carrot juice for lunch, then die destitute. The influence seems to have been temporary though. He continues to lend respectability to many dodgy meetings. He edits the Cancernet web site. This site lends credence to bizarre treatments like homeopathy and crystal healing. It used to sell hair mineral analysis, a well-known phony diagnostic method the main purpose of which is to sell you expensive “supplements”. They still sell the “Cancer Risk Nutritional Profile”. for £295.00, despite the fact that it provides no proven benefits.
Robert Thomas designed a food "supplement", Pomi-T: capsules that contain Pomegranate, Green tea, Broccoli and Curcumin. Oddly, he seems still to subscribe to the antioxidant myth. Even the supplement industry admits that that’s a lost cause, but that doesn’t stop its use in marketing. The one randomised trial of these pills for prostate cancer was inconclusive. Prostate Cancer UK says "We would not encourage any man with prostate cancer to start taking Pomi-T food supplements on the basis of this research". Nevertheless it’s promoted on Cancernet.co.uk and widely sold. The Pomi-T site boasts about the (inconclusive) trial, but says "Pomi-T® is not a medicinal product".
There was a cookery demonstration by Dale Pinnock "The medicinal chef" The programme does not tell us whether he made is signature dish "the Famous Flu Fighting Soup". Needless to say, there isn’t the slightest reason to believe that his soup has the slightest effect on flu.
In summary, the whole meeting was devoted to exaggerating vastly the effect of particular foods. It also acted as advertising for people with something to sell. Much of it was outright quackery, with a leavening of more respectable people, a standard part of the bait-and-switch methods used by all quacks in their attempts to make themselves sound respectable. I find it impossible to tell how much the participants actually believe what they say, and how much it’s a simple commercial drive.
The thing that really worries me is why someone like Phil Hammond supports this sort of thing by chairing their meetings (as he did for the "College of Medicine’s" direct predecessor, the Prince’s Foundation for Integrated Health. His defence of the NHS has made him something of a hero to me. He assured me that he’d asked people to stick to evidence. In that he clearly failed. I guess they must pay well.
I think Ioannidis is just saying the effect size in PREDIMED is probably exaggerated due to the trial being stopped early for benefit.
That was certainly one reason, but Ioannidis gave several others too.
I don’t disagree with Ioannidis, but I guess what I’m reacting to is that in the text of your post, you make it sound like PREDIMED should be completely ignored because of statistical unsoundness.
I don’t think that anyone said that PREDIMED should be ignored entirely. But the large effects that are claimed are so out of line with other information that they should most certainly not be taken as the last word on the subject.
I completely agree!
By the way, I heard some interesting news today on the randomized trials front. A trial is being done on the effect of moderate drinking on incidence of MI, stroke and type 2 diabetes. I will paste in the relevant paragraph, since it is in the Wall Streeet Journal, which has a paywall.
“Researchers plan to enroll 8,000 subjects who are older than 50 and at risk for heart disease. Some will be randomly assigned to abstain from alcohol and the others to have one drink a day. The study will compare the incidence of heart attack, stroke and Type 2 diabetes in the groups after about six years. It isn’t designed to measure cancer risk.”
The trial is being funded by some alcohol manufacturers and the article says it is being overseen by the U.S. National Institute of Alcohol Abuse and Alcoholism. It’s unclear from the article if it also has U.S. government funding.
‘We know little about the effect of diet on health. That’s why so much is written about it’.
I would beg to differ for two reasons.
1. Continuous turnover of cells, cellular components and peptide hormones and catabolism of amino acids for gluconeogenesis requires substrates, all of which are supplied per os.
2. Deficiency conditions suggest that diet does affect health.
3. Therapeutic dietary manoeuvres have health benefits:-
Ketogenic diet for treatment of intractable epilepsy
Phenylalanine-free diet for PKU
Pancreatic enzyme supplements and MCT/LCT based diets for cystic fibrosis
Total parenteral nutrition for patients with intestinal failure
Iodine supplementation in areas of deficiency, to prevent goitre and low IQ in children
I could go on, but these are fairly standard examples with a long history. A balanced diet which meets macro- and micronutrient needs is not a binary choice.
What you seem to be hooked on is the “one drug, one target” paradigm and there we might agree on some things. If you brush aside the obvious fraudulent claims of efficacy (e.g. Spirulina – pseudovitamin B12, which is biologically inactive in humans), there is a growing evidence base for efficacy of food ingredients extracted from some waste product or other which might help in treatment of obesity (e.g. chitosan).
There have been some systematic reviews of efficacy and side-effects. The effectiveness seems weak.
In my opinion, it would be better for people to follow a pukka weight-reduction programme and change their dietary habits, than to buy this stuff over the counter and risk drug-nutrient interactions (e.g. valproate).
I think that you need to read a bit more about nutrition and nutrient requirements before laying into “nutrition” wholesale. There are some charlatans in every subject, but not all of us are charlatans.
In the case of real nutritionists (unlike most of those discussed in this post), I’m certainly not accusing them of being charlatans. Research in the area is hard because of the difficulty of doing proper RCTs.
But there is no doubt that real nutritionists must bear some of the responsibility for the constant barrage of advice about what to eat. The fact that that advice is so often contradictory itself shows that the information on which it’s based is quite dodgy. It can’t all be blamed on Ancel Keys’ promotion of fat-free diet advice. Similarly dubious advice is still pushed onto the public, almost daily.
I agree with John Ioannidis that much of this advice is likely to be plain wrong.
I’m really disheartened to read that Phil Hammond chaired this meeting. I shall in future read his Private Eye “M.D.” columns with a cautious eye.
David, I suspect you have fallen victim to your own success in unmasking dodgy “nutritionists”. I’m a nutritionist, but definitely not dodgy, yet it rankles that you still make sweeping and prejudicial statements about the area. The same critique could be made of pharmacology which is a positive hotbed of spin and contradictory advice.
I’m old enough to have observed the changes in treatment of gastric ulcer disease from truncal vagotomy, highly-selective vagotomy, antacids, H2-receptor antagonists, proton-pump inhibitors and, finally, antibiotics to eradicate helicobacter. We published the first UK paper on the 13C-urea breath tests. Each step in this progression was trumpeted by pharamcologists. I have to say that advice on HRT is also quite contradictory. No-one in their right would use this as a stick to beat the dignified high science of pharmacology, would they?
The issue at point is the strength of data which supports current dietary recommendations. It is quite good and we know not only the minimum requirements of each macro and micronutrient, but also the optimum requirements for dietary fibre, for example. Humans can run on a variety of fuels but our complexity as mammals means that differentiating long-term outcomes from lower-fat or lower-carbohydrate diets (for example) is hard to determine because of the plasticity of our systems. It’s much easier for pharmacologists working on one-drug/one-target and I envy you in that respect.
Nutrition is a subject that seems to attract a lot of attention from non-experts (very much like teaching, where everyone seems to know better than teachers). There is of course a lot of very dubious research out there – poor trial design, poor interventions, poor interpretation of data; very much like in many other fields, including medicine.
But there are some challenges which are unique to nutrition and poorly understood by outsiders and critics:
– Double blinded-RCTs are not always possible. This can be done for individual compounds (e.g. Vitamins, where it has been done), but it already becomes nigh-impossible with individual foods because creating a placebo is very difficult and expensive. With dietary interventions, it is impossible as subjects can’t be blinded – and it is extremely difficult to change subjects’ diets (PREDIMED put a lot of effort into this with limited success).
– the effect of diet on health (especially chronic diseases) is often very week and takes a very long time to emerge (even for smoking, it takes many years to show an effect on lung cancer or CVD). Therefore, very long, very large trials would be required – something that is simply not possible.
– biomarkers (or surrogate endpoints) are often rejected by critics, even though they are very commonly used in their own disciplines. These biomarkers need to be validated carefully, of course – but as long as they act as a marker (and not a target), they can be very useful. There are extensive reports by IOM, EFSA and ILSI Europe about this.
– observational studies are therefore the best alternative – but they need to be conducted and interpreted carefully. Exposure assessment is difficult and requires expert knowledge and support by epidemiologists and statisticians – suggesting that those people do not understand the difference between correlation and causation is disingenuous – perhaps it might be worth to have a look at some of the methods before outright rejecting them (http://epi.grants.cancer.gov/events/measurement-error/)
There is a lot of pressure from certain areas (especially the Arnold Foundation, but also people like Taubes, Teicholz, Harecombe or Malhotra) to discredit nutrition research and push the ‘low carb’ agenda. One of their approaches is to discredit anyone with any links to industry – as if industry funding was resulting instantly in poor quality research. In my experience (and I have been on more than one panel reviewing evidence), industry funded studies (at least those by the large companies) are generally of better quality, adhere to the appropriate criteria (e.g. CONSORT) and follow proper GCP (including data monitoring team and statistical support).
I, too, agree with Ioannides: “Even if the impact of dietary risks is one tenth of that suggested by the burden of disease study, it still deserves attention.”
Thanks to George Grimble and to BGeoffrey for their comments. They might perhaps have been more appropriate on my my posts about serious nutrition, rather than this post which is (mostly) about the vast quack nutrition industry.
They would have been more appropriate on “We know little about the effect of diet on health. That’s why so much is written about it“, or on my posts about red meat.
I have every sympathy with real nutritionists. As you point out, it’s almost impossible to do proper experiments. Indeed that’s precisely why so little is known with any certainty. Despite your protestations, it remains true that, as Ioannidis said
It does seem a bit irresponsible to deny this fact. It is, surely, the main reason that most of the public just laugh when the latest dietary dictum is handed down.
You (BGeoffrey) say
This is often said, but I’m always baffled by what exactly “carefully” means. No amount of care will remove hidden confounders.
You go on
I have no doubt that epidemiologists and statisticians understand the problem of causality. It’s explained carefully in the introductory parts of the WCRF report on diet and cancer, and that was edited by Professor Sir Michael Marmot, someone for whom I have huge respect Nonetheless, when I went carefully through the evidence for causality that was presented for red meat, I found it very unconvincing. And my scepticism seems to have been justified by subsequent events.
I fear that it’s true that epidemiologists, even the most distinguished of them, operate an extreme form of the precautionary principle. Despite the warnings about causality in the introduction, when it comes to the advice at the end, every small association is assumed to be causal.
I suspect that the tyranny of “statistical significance” also has a role in the crisis in reproducibility that we are living through (not just in nutrition studies, of course). It is still very common to hear people say that if a criterion of P < 0.05 is used to claim “statistical significance”, that means that the probability that your results occurred by chance is less than 5 percent. Of course it doesn’t mean anything of the sort. But ignoring false positive rates is too convenient for getting published for people to learn about it. Journal editors are also resistant to it, on the shameful grounds that it might decrease their impact factor if they were to treat false event rates properly.
I blame the culture of publish or perish, the preference of journals for positive outcomes, and the preference of the media for bad news and sensational results.
It would be hard to do a survey that lasted for years, and conclude that it didn’t provide enough information to allow any public health advice to be offered. But only too often that should be the conclusion. In my more extreme moments, I sometimes wonder whether observational epidemiology has had its day.
Your penultimate paragraph describes a key problem very well – but I don’t think the best solution is to make life difficult for all those who (try to) conduct proper research.
You comment on the word ‘carefully’, and this is obviously a very vague term here – what I mean is that results from observational studies don’t stand alone, they need to put into context, and that’s something that often doesn’t happen. Moreover, authors are too fixated on numeric results that they forget to look at the actual data they have (the number of publications finding a trend in data that simply shows a threshold effect, probably because there’s a difference between consumers and non-consumers). Or reviewers and editors that insist on making an ‘trending towards significant’ from p=0.1 or insist on describing p=0.04 as a meaningful finding (even though it is obvious that it isn’t). Statistical tests are very useful, but they need to be interpreted properly … (but of course this is what you have been saying for some time).
I don’t agree with your last statement – I still think observational epidemiology has an important role to play (and if it is to keep me happy until my retirement …). There are a lot of questions that can’t be answered differently, especially those relating to long-term exposure or the interaction of social factors and behaviour. But we need to change the way these studies are conducted and interpreted.
At the moment, the tabloidisation of science results in a very unpleasant environment where sentiments and opinions have become more important than facts. Those of us who try to do our work properly aren’t helped by constant attacks from all sides on our research – from those who believe that we are quacks and from those who believe that we are in the pocket of industry. This summers’ hoo-hah about fat and carbohydrates has probably caused more damage than it did good – because a small but vocal minority gives the impression that the consensus is completely wrong (very similar to anti-vaxxers or climate-change deniers).
What would help – at least in my humble opinion – would be a more respectful way to interact with each other. Assuming that most people have good intentions, it is better to find the positive and not focus on the negative.
As a (fairly junior) scientist working in the often criticised field of observational epidemiology, I’m obviously quite sensitive to the accusations coming from all sides.
I can’t quite agree about “the hoo-hah about fat and carbohydrates”. One of the most interesting aspects og Gary Taubes’ book was his description of the history of how Ancel Keys managed to persuade a generation to adopt his low fat ideas on the basis of very slim evidence, much of which has subsequently proved to be wrong. Similarly the alleged dangers of red meat are, almost certainly, illusory. It’s taking a remarkably long time for nutritionists to admit that they got it wrong, and that’s worrying. None of this is to say that I subscribe to the extreme Malhotra versions of the ‘white powder [sugar and salt] is poison evangelists. All I wish is that people would stop over-interpreting weak associations.
Incidentally, Taubes has written one of the best accounts of why randomisation is so important -in the New York Times!
I regret the “tabloidisation” of science as much as anyone. But I don’t blame that entirely on journalists. Journal press releases, and those from universities (which have been approved by authors) are, far too often, hyped up, and that’s refelcted in what the journalists write.
Gary Taubes might be a good writer, but he does have a mission and is therefore – in my opinion – biased. Whether Keys manipulated data (as is claimed) or not is of historic interest as there are many studies not conducted by Keys investigating links between fat intake and disease risk, largely confirming it.
We have been getting better measuring fat intake, from using secular data to more advanced instruments such as FFQs, diaries and biomarkers, and especially the latter give us a very good idea what people actually consume. Odd- and even-chain SFAs seem to have a very different – indeed opposite – effect on health, so combining those two (which has commonly been done) results in a much weaker observed association.
There are a number of large biomarker studies (not only for fat but also for polyphenols) which should give us a much better idea about associations between intake and health.
I don’t know much about meat – but the data I’m aware of does suggest to me that there is probably a small effect. Whether meat consumption acts just as a surrogate marker for something else or not is a different question. Measuring meat intake is quite different as a lot of meat is hidden in different foods (something that can’t be easily assessed by FFQs and requires a lot of work with diaries) – and there are no objective markers for meat intake at the moment. Attempts to measure HCA/PAH were not very successful as their formation depends on processing/cooking methods.
This is a very interesting discussion but, BGeoffrey, you shouldn’t be so defensive about methodology in nutritional epidemiology. FFQ and diet diaries have limitations. So what? All measurement methods have their limitations and we can accept that without thinking that the pillars in the temple are about to collapse. This specific limitation has been known for a long time and thinking on this was crystallised in Gail Goldberg’s paper on cut-off values for implausible reported energy intakes which should be ignored in nutritional surveys. I repeat the same experiment with UCL MSc and MBBS students and every time, 85% will have underreported their intake according to Goldberg’s cutoffs. It is salutory for the students and in a general sense has spurred on development of better methods to correct for underreporting of sugar intake (urinary sucrose excretion). It has also led to more use of good measures of energy expenditure in free-living, hairless, bipedal mammals. When one considers that development of obesity in a man over 30 years involves a mismatch of intake/expenditure of 20-25 kcal/day (or about 1% of total energy expenditure) then you can see the technical challenge involved in measuring this.
Coming back to you the assertion that it is extremely difficult for nutritionists to perform controlled experiments, I’d respectfully refer everyone to the field of clinical nutrition where this happens a lot of the time. In fact, the ESPEN conference in Copenhagen, this week, focussed on the many PRCTs and meta-analyses of trials in critical care nutrition.
Clinical nutrition is a very different field – because the effect can be observed directly and it is much easier to control. There is a big difference between say branched-chain amino-acids in TPN and increasing the amount of olive oil in the diet over several years. (I’m somewhat envious of clinical nutritionists in this context.)
Regarding the instruments: FFQs are incredibly crude instruments that work fine only for the nutrients they have been designed for. Using them for anything different (now very popular are all sorts of plant metabolites) is always difficult (and IMHO not really appropriate). Multiple 24HDR are probably best, but expensive and difficult to conduct.
Emerging technology (especially apps such as MyMealMate or the ASA24) is probably the future and will give us much better data.
Biomarker are good, but limited to existing samples, existing timepoints, funding and expertise. I’ve been involved in a few large-scale biomarker projects, and they are incredibly complex and expensive – which means obtaining funding is difficult. The scale makes rigorous QA imperative, something that adds cost and is often seen as redundant. And apart from fat and protein there are not many very reliable markers. There are a few interesting ideas such as sugar (although there are still some limitations) and a few exotic ones – but whether they can be applied successfully has to be seen. There are too many failed attempts (Methyl-Histidines, TMAO) and metabolomics didn’t really achieve much despite the amount of funding used.
I think I agree with some of David’s concerns about nutritional research, I just don’t agree with the conclusions as I know we can do better.
You’re correct with regards to many of the limitations nutritional studies face. You’re incorrect with one: the difficulty in creating RCTs. Let me explain.
With any RCT, we should be testing the intervention that is most like the intervention that we intend to put in practice (assuming our hypothesis checks out, of course). When it comes to nutrition, that intervention is not likely to be IV administration of some vitamin; it is not likely to be lying to people about what they’re stuffing into their sandwiches. It is instead likely to be advice about how to eat in order to increase the chances of living a long and healthy life. And so the interventions we should be testing are not any particular diet, but rather the advice to follow some particular diet. Because there is no such thing as a placebo diet, of course, we’ll never be looking at if our diet is “effective”– what would that mean?– but rather that it leads to less all-cause morbidity/mortality than the standard of care. In that sense, creating a control is ridiculously easy. You educate your control group carefully on current recommended diets and tell them that you want them to eat that way. (Then you watch. For fifty years, hopefully.) Yes, compliance is an issue– just as it will be when you roll out your intervention. And thankfully, issues related to compliance, like bingeing in response to unrealistic demands, will show up in your trial and not blindside you long after your roll out.
You say, surely there is a place for observational studies in nutrition. And there is, just as there is a place for observational studies in all fields. It is the same place. It is in the generation of hypotheses. As long as nutrition limits itself to these observational studies that are incapable of showing causality, all it is doing is creating hypotheses. (I believe there are now enough. Time to get to the experimental work.) Will it be hard to go further? Yes! Science is hard. It is often expensive. We’re not going to know everything before we die. None of this is an excuse for calling the cheap, not-really-good-enough version science.
Finally, I wanted to comment on the disconnect between two of your statements. In one comment, you complain about how many disregard science performed with industry funding; in the next, you complain about Taubes’s agenda that pollutes all of his work. I hope you can see that these are really the same thing, seen from two different perspectives. When it comes to diet, every one of us has an agenda from a lifetime of eating, something that approaches such a moral level that all of the world’s major religions make rules about it. Food is bigger than sex, bigger than drugs. What’s important to recognize is that we all have that agenda, and that it creates bias in all of our work. This is even more reason to be suspect about dietary research. So it’s even worse than you think: not only are we going to need huge studies that last past the primary author’s death, we’re going to need more than one of them, because this is a field where we need actual reproducibility and not the assumption of it that we’re all used to accepting.
Thanks for your perceptive response to BGeoffrey’s comments.
I couIdn’t agree more.
@vaslin – thank you for your reply, but I believe it ignores some of the important fctors.
Your suggested RCT protocol is very limited because dietary interventions are not limited to dietary advice. They can also include the provision of supplements, the fortification of food or other measures to promote certain dietary patterns (the sugar levy is one example). If we want to understand how diet can affect health, we need to ensure that we observe the effect of diet itself – not that of dietary recommendations. Your suggested protocol does the latter. And a control group as you suggest would only be possible if you were to separate these groups – which is practically impossible over a long time. We have conducted such type of studies over a fairly short one-year period and within this time it was impossible to ensure advice did not reach the control group.
You call observational studies ‘cheap’ (which they aren’t) – but for many questions there are no viable or ethical alternatives. It would not be ethical to expose participants to foods or compounds that are potentially dangerous (or deprive them of foods that might benefit health). You suggest RCTs on dietary recommendations: on what would you base these recommendations? These patterns have to be established first – and I there are not many alternatives to observational studies.
The fact that many of those studies are used to create poorly written papers should not be equated with the quality of the data and the opportunity the data presents. But take fibre as an example – observational studies were crucial in establishing its role. I agree we need both – but I disagree that we have enough from observational data.
Finally regarding Taube: the problem I see is that industry is seen as biased per se, whereas here Taube’s book is seen as a more objective contribution. He has a very clear agenda and it has been shown more than once that his books are very biased (for example his account of low-fat guidelines). It is a bit like Guardian and Daily Mail – people trust the former, even though both are equally bad and biased. Or fruit juice and coke: fruit juices contain often more sugar but are believed to be healthy.
I would like to recommend the following report by Yetley et a.:
This report deals with the development of dietary recommendations, but discusses quite extensively strengths and weaknesses of different types of studies (including RCTs and observational cohorts) and the use of surrogate endpoints. The authors are neither complete novices nor entirely uncritical of current methods – but come to rather different conclusions.
Why is everything a “NO”?
I’m not sure that I understand your question. I’d put it thus: why is there so much dishonesty and misunderstanding about? The dishonesty is a result of people valuing fame and money above honesty and helping the sick. The misunderstanding results from poor education about statistics and trial design.