> BTW, what I like most about John Ioannidis's work is that he not only proved theoretically that most medical research is false
"Proved" is being thrown about a bit liberally in connection with Ioannidis' work. It's certainly in dispute [1]
Either way, it seems your central point has a number of flaws. What you are attributing to superstition (e.g. consuming more leafy greens) is in fact more often than not rational decision making based on admittedly limited information.
Will the consumption of vegetables ultimately improve ones health? I don't know, let's take a more specific example. For instance, take someone interested in positively affecting their likelihood of developing diabetes. A quick google search turns up a study that notes a correlation between increased vegetable intake and a reduced risk of diabetes[2].
Of course, increasing intake of green vegetables may mean a decrease in some other substance. Another quick search turns up a research study documenting a link between increased fructose consumption and insulin resistance [3]. Thus, if I were hypothetically interested in positively affecting my insulin response, it would be quite logical to increase my consumption of green vegetables while decreasing my intake of sugar.
Is this course of action wrong? Possibly. However, it's certainly rational and not exactly "superstitious". You've defined the term so loosely as to encapsulate even such things as making rational decisions based on limited information. That is certainly not what superstitious really means. Certainly, someone who refuses to change their dietary habits despite ample refuting evidence could be classified as superstitious, but that's not a distinction you have made.
> However, many of the epidemiological studies are over very large populations and time periods, so it's not as though the body of evidence consists of a 6-8 week studies. And honestly the fact that the effects are so strong in such a short period of time strengthen the argument in some ways.
The studies all tell us nothing about the long term implications of diet. The long study tells us nothing because it is purely correlational. The short studies tell us nothing because they are not measuring the thing we care about (long term health outcomes). You can't somehow generate knowledge by combining two types of studies which each are incapable of generating knowledge about the thing we care about.
> I never claimed that meat was bad, only that leafy vegetables were good.
Yeah, I clearly was hallucinating. Nowhere did you mention red meat. And yet I rambled on about it for a paragraph. :-) Sorry!
But:
> I find it almost incredible that your argument against the nutritional value of leafy vegetables is that there aren't enough double blind clinical trials, and then your defense of red meat uses a time correlation that doesn't adjust for any confounding variables at all.
That's because correlation cannot demonstrate causation, but it can demonstrate the lack of causation. It's all about confounding variables, as you point out. If you have two trend lines which correlate, there can always be a third, unmeasured variable which is actually causing the two measured variables. However, if you have trend lines which do not correlate, then the only way they can be related is by some extremely convoluted chain of causation. Which, I guess, is technically possible, but rapidly approaches 0 probability.
In other words, epidemiology is very useful for narrowing the possibly explanations for some phenomena, and it can suggest places where we should continue focusing our attention, but it can't actually tell us if we've found the right culprit.
> I don't roll my eyes at people who tell me carrots are healthier than potato chips, even though I don't really understand nutrition or digestion. There's nothing wrong with trusting experts.
Nutrition is a specially bad example. There are plenty of studies that are overhyped and make crazy claims about why some food is good or bad for you, but the are not reproducible, have a small sample number, barely reach p=0.05 using p hacking. And a few weeks later you can read a equally bad study with the opposing conclusions.
For example "I Fooled Millions Into Thinking Chocolate Helps Weight Loss. Here's How." http://io9.gizmodo.com/i-fooled-millions-into-thinking-choco... It's a bad study made on purpose, but the problem is that many studies have the same bad methodologies. Are eggs good for you? The food pyramid?
Nutrition is a good example of a field were you have a very complex system and you can´t make very controlled experiments, so it's very difficult to make reliable measurements.
>For example, people who like the taste of plants are probably far less likely to enjoy eating red meat, salty foods, and many other things that have been associated with increased mortality.
Which, incidentally, have really only been associated with increased mortality through flawed epidemiological studies such as this one.
> Science does not in fact prove only fruits and vegetables are good for you
I will agree with your objection to the “prove” claim about the science (if only because it’s an overstatement of what science does) but the negative associations between various adverse health outcomes and a plant-based diet are well-supported in the literature: lower risk of type 2 diabetes, lower systolic BP, lower risk of cardiovascular events, lower total cardiovascular mortality, lower rates of certain malignancies.
> with the number of dietary science that turned out to be wrong over time, I must be skeptical about every new study.
This I agree with. There is so much noise and so many confounding factors affecting the underlying data that you are bound to frequently get conflicting results. Compound this with the fact that studies with the most surprising (read: contrarian) results tend to get the most press, and you get an infinite see-saw in the literature.
> Am I wrong to have suspicions about the possibility that food conglomerates may have funded this study?
This I don't agree with. I think your model of more fasting equals less spending on food is overly simplicitic. The sort of health conscious people who are interested in IF tend to be wealthy and willing to spend on premium health related products. I'd wager that you can make a lot more money selling a few premium, organic, protein bars that you pitch as premium feel-full-for-12-hour-guaranteed products than you can by selling the same old breakfast cereals.
Besides, Occam's razor. Intermittent fasting is not a subject where there is or ever has been an overwhelming consensus in the literature, as opposed to say, climate science. It's not surprising or suspicious in the least to see a contrarian result in this field.
> Generally in the community people theorize all kinds of things about diet and some are lucky to reach and stay in remission by eating a narrow diet that agrees with them - but what exactly that is varies wildly across individuals. I've never found a common thread.
It also really looks like a methodology problem on the medical science side to me, statistics easily nullify important data when variables are difficult to control.
> For example, what you eat is shaped far more by what you see than by what you search for.
The linked study is co-authored by the disgraced researcher/fraudster Brian Wansink. I guess this was one of the studies that didn’t get retracted, but I still wouldn’t put a lot of faith in anything with his name on it.
> The Mediterranean diet has been linked to longer lifespans
Did you read anything I wrote? Every single fad diet in the world has multiple scientific papers showing how great it is. (p = 0.05. Nevermind that there were 1000 research projects about this fad diet that didn't get published because they didn't reject the null hypothesis, so who cares. Nevermind that nutrition scientists don't practice good behavior to mitigate the effect of the base rate fallacy on popular subjects.)
Almost no scientific fields practice enough discipline to have very high predictive power. Particle physics mitigates base-rate failures by having an extremely high confidence requirement (5 sigma). Even with absolute best practices, it's sometimes not enough. http://slatestarcodex.com/2014/04/28/the-control-group-is-ou...
> They actually adjusted for age, smoking (never, former, current), pack-years of smoking, energy intake using the USDA's HEI, alcohol intake, physical activity (some/none), BMI, and waist circumference.
All of which are self-reports (food and energy intake as a self-report, when it's well known in the field that self-reports are flattering? and you have the gall to imply that this is good reliable science) or based on weight, just as I said. Please think a little more about this.
> I'm not sure what you're trying to imply with this one though.
What...? OK, I'll charitably assume you're just ignorant here of problems with dietary research and explain (hopefully I won't be wasting my time and receive a response of 'I WANT TO BELIEVE'): whenever a large regression like this is run, there are always many correlations with various behaviors and food consumption; for example, people who eat nuts or blueberries or who exercise regularly or take statins are also people who tend to live longer on average or have other good outcomes. It is tempting to implicitly assume that eating blueberries is a random practice in the population and so this shows that blueberries probably cause you to live longer; however, it is also true that blueberries are widely believed by the general population to be healthy foods, and so the sort of people who pay for and eat blueberries (or claim to eat them, anyway) are also the sort of people who are in good health, are health-conscious, will follow their doctors' orders, comply with drug dosing regimens or regularly test their blood glucose, etc. This bias is universal, and this is why, for example, in the infamous Nurses's Study, hormones seemed so great when they turned out to be murderous in randomized practice: because hormones were believed to be healthy, it was healthy compliant nurses who self-selected into use of hormones and because they were healthy and complaint, had good outcomes anyway.
So, what is a warning sign of healthy user bias? It's when the common trait among harmful/beneficial correlates is whether they are generally believed to be harmful/beneficial even when the supposed causal chemical mechanism is inconsistent. In this case, soda is considered by the general population to be unhealthy, diet soda to be healthier (it's got diet in the name!), and fruit juice the healthiest of all. The former seems to be bad, and the latter two good or at least neutral. And why would soda be so harmful? Well, generally you'd suggest the acidicness or the sugar content; except... either of them should cause either diet soda or fruit juice to be harmful (acidicness or very high sugar content, respectively). But there is an explanation resolving the lack of harm for either: people with better health habits or interest will preferentially consume diet soda or fruit juice and avoid awful soda... and if we correlate consumption with outcomes, we'll find the soda drinkers have the worst outcomes. Voila: healthy user bias.
(You see something similar in studies of maternal smoking or smoking by pregnant women; the effect seems dramatic and harmful to the child, but consider this: given that everyone believes only the worst mothers in the world would smoke while pregnant, what sort of woman would over the past decades smoke while pregnant? Probably not one who plans ahead, is self-disciplined, health-conscious, rich, or intelligent, all of which are heritable, and are difficult if not impossible to completely measure in all their manifestations & remove as confounds.
If you wanted a more accurate analysis, taking this possibility into mind, you might do something like find women who smoked while having one child and didn't smoke while having a second child, and compare pairs of children; then you'll find that the harmful effects mostly disappear.)
This cannot be adjusted away simply by a few self-reports because it is a systematic subtle effect on all life outcomes - for example, to name just 2 of the lurking confounds, in other studies one can find longevity boosts to IQ and Conscientiousness for what is suggested to be the same exact reason (more likely to understand or carry out good health practices, respectively), but neither of those was measured by this study.
> It's surprising how the general public seems to rely on research instead of first hand experience.
But medical research assumes that first hand experience can be deceiving, because of placebo effect. It also considers the impact self-deception on researchers, and tries to remove that effect with double-blind studies.
I find it difficult to believe that dietary changes that require a consistent level of engagement, both to be mindful of what you eat and to resist temptations, can be free of placebo effects. And since you're also evaluating subjectively the effects, you are also prone to the researcher's self-deception.
Science is the last place I'd look if I wanted information about diet. Some of the worst, least reproducible stuff comes out of the nutritional science world. You can find studies for and against every diet and class of food.
The best place to start is tradition. What have you and your ancestors traditionally eaten? From there, make changes based on how you personally react to certain foods. From here, you can now very carefully look over some scientific studies to somewhat corroborate the effectiveness of your traditional diet.
But this is not nearly enough. As you do this, you have to be mindful of frequency; seasonality. Maybe your tribe kills a mammoth and you eat nothing but steaks, fat, high meat, and jerky for a month. Maybe your hunters come up short for the next month, so you live on foraged berries and rationed pemmican. In winter storms, the last thing you want to do is venture out into the crippling blizzard, so you subsist on stored tubers, or maybe you just starve for a week (you'll be fine). Maybe this kind of randomness is what your body is adapted for. Maybe this is your ideal diet.
Maybe Jews, Christians, and Muslims discovered the benefits of randomness in their diets and that's why they codified the practice of fasting in their books. And maybe there actually is some modern valid science to corroborate these ancient traditions.
>"If the results are true, this gives another reason to boost your fruit and veg intake. We already know eating these foods is good for physical health, and this study suggests they can improve your mental health, too."
I feel like this is nothing really groundbreaking news. I don't have any scientific sources or proofs so maybe I'm retarded, but it was always obvious to me that physical and mental health are largely interlinked. People who exercise regularly are more likely to have better mental health, perhaps even regardless of their diet (counting out extreme cases). People who make an effort to eat more fruit and veg to improve their physical health generally are also practicing the mental discipline needed to stick to a long-term plan/goal, which will mean better mental wellbeing as a result.
Will this study do any good to motivate people to eat more healthily? The cynic in me tells me no, because everyone already knows fruit and veg are good, yet many will still refuse to incorporate them into their diet and choose to eat convenient junk instead. The people who are already eating fruit and veg already know it is making a positive impact on their health, I guess this is another form of confirmation for them so they can continue?
>sure natural=better is not a rule true 100% of the time
It isn't even a loose correlation. It is no better than random.
>One example is how it became clear in the last years in nutritional science that in general the more processed the food is the more harmful it is for us.
That has not become clear at all, that is something people like to repeat, but is simply a misinterpretation of the recommendation that people "eat mainly unprocessed foods" to maintain a healthy weight. The recommendation is not due to some magical pixie dust inherent in unprocessed food, it is because processed foods are often very high in calories.
>There is also the reverse problem, illustrated by the condescending attitude toward herbalism in this article, of people who idealize modernity, and for example believe only medicine in the form of pills can be effective, even though plants may contain exactly the same chemical compounds.
Except the article had no such attitude, and said nothing like what you are suggesting it says.
>In general I think it is ridiculous to ignore the thousands of years of experimentation and exploration of our ancestors just because it wasn't "science-based".
It isn't ignored. It is studied, and if it is found to actually be effective, it is used. If it is found not to be effective, it is not used. The quack/fraud "medicine" crowd really need to grow out of lying about this. Scientists do not ignore old herbal remedies, they study them.
Yeah, sure, we’re made to primarily eat something you can’t find for 9 out of 12 months. How do you keep believing this crap?
> Yes. It's been shown again and again in large studies that humans do better on predominantly whole plant foods.
No, it really was not. Any research you link to will be riddled with problems like measuring the wrong thing or affected by heathy user bias. Just because it confirms your belief doesn’t make it a good source.
I am skeptical of the conclusion because of the imprecise language. For example, concluding ritual may be more effective than stringent dieting. 1. What is the documented efficacy of dieting over the same limited time period? 2. Are dieting and ritual mutually exclusive?
Is eating a carrot instead of chocolate necessarily a demonstration of will power? At least with the other studies, the subjects had a stated goal of weight loss.
How many subjects participated? Were the trials run more than once? The scholarly articles are paywalled, so all we are left with is this article. And this article seems more fitting for a grocery store checkout line rag than for Scientific American.
> overwhelming majority of scientists claim that consuming meat in quantities we do in North America is not good for health
Does your skepticism (which by the way does not really disprove anything what the scientist who wrote this article says, and rather simply tries to discredit it) also extend to these "overwhelming majority of scientists"? Because if it did you will understand that nutrition epidemiology studies are not scientific experiments; they are wildly inaccurate, questionnaire-based guesses (hypotheses) about the possible connections between foods and diseases. This approach has been widely criticized as scientifically invalid [see here(1) and here(2)], yet continues to be used by influential researchers at prestigious institutions.
Even if you think epidemiological methods are sound, at best they can only generate hypotheses that then need to be tested in clinical trials. Instead, these hypotheses are often prematurely trumpeted to the public as implicit fact in the form of media headlines, dietary guidelines, and well-placed commission reports like this one.
Tragically, more than 80%(3) of these guesses are later proved wrong in clinical trials. With a failure rate this high, nutrition epidemiologists would be better off flipping a coin to decide which foods cause human disease.
> there's no way the brain can tell I've eaten 1/3 meat and 2/3 salad vs 3/3 meat in the span of 15 minutes
Again, I think this is trusting too much in "today's science". Who's to say that your body/brain can't detect whether a food is nutritious? For all we know, some trace nutrients are subconsciously detectable in taste and smell, even if heuristically.
I'm not saying that is what happens, but I don't think we know nearly enough to dismiss such a possibility.
Nutrition science has been around for decades and people get PhDs in it. Like in most fields medicine there's always space to discover more but claiming that data is "scarce" is exaggerated.
> lacking solid information at a population level it's irresponsible to promote diets that may cause harm.
> To not advise people to do things that may deprive them of necessary nutrients, is the responsible thing to do.
There are millions of people in the world facing risks related to obesity like hearth attack and following other bad diets due to ignorance, or poor availability of healthy foods, or following absurd fad diets.
Of all irresponsible diet advice that can be given... you are clearly painting a boogeyman, like the article does.
> I know, but when is the last time you saw a diet recommendation article of the form "Our Bayes factor on kale doing such and such is..."?
The only things 99.9% of people pay attention to (or know how to interpret) are authoritative-sounding recommendations, so that's what diet writers write.
Attacking writers (to no disagreement from me) is a pretty odd response to a defense of science's role in society. Science coverage is garbage, but that has approximately nothing to do with your point, nor my response to it.
> No, I think you actually misunderstand what science can do for us here. Science can give us confidence intervals that let us maximize expected utility given what we know. We don't just assume that the most likely hypothesis is true.
Oh for the love of God, this is a masterpiece of pedantry. You're mistaking "I assume everyone here is intelligent enough to understand what I'm getting at despite my lack of precision in a brief three-sentence comment" for "I don't understand what I'm talking about". Just because you don't fit the former statement doesn't mean I fit the latter.
"Proved" is being thrown about a bit liberally in connection with Ioannidis' work. It's certainly in dispute [1]
Either way, it seems your central point has a number of flaws. What you are attributing to superstition (e.g. consuming more leafy greens) is in fact more often than not rational decision making based on admittedly limited information.
Will the consumption of vegetables ultimately improve ones health? I don't know, let's take a more specific example. For instance, take someone interested in positively affecting their likelihood of developing diabetes. A quick google search turns up a study that notes a correlation between increased vegetable intake and a reduced risk of diabetes[2].
Of course, increasing intake of green vegetables may mean a decrease in some other substance. Another quick search turns up a research study documenting a link between increased fructose consumption and insulin resistance [3]. Thus, if I were hypothetically interested in positively affecting my insulin response, it would be quite logical to increase my consumption of green vegetables while decreasing my intake of sugar.
Is this course of action wrong? Possibly. However, it's certainly rational and not exactly "superstitious". You've defined the term so loosely as to encapsulate even such things as making rational decisions based on limited information. That is certainly not what superstitious really means. Certainly, someone who refuses to change their dietary habits despite ample refuting evidence could be classified as superstitious, but that's not a distinction you have made.
[1] http://www.technologyreview.com/view/510126/the-statistical-...
[2] http://www.eurekalert.org/pub_releases/2010-08/bmj-glv081810...
[3] http://www.nutritionandmetabolism.com/content/2/1/5
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