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November 22, 2013 / JayMan

Nuts Over Nuts

This was on NBC Nightly News two nights ago:

“The evidence would suggest that if one chooses nuts over other alternative foods, there is potentially a 20% improvement in mortality, which is quite striking.”

I’ll say. Does this mean you have a 20% better chance of dying (to follow my wife’s tendency to interpret things literally)? Or does it mean I have a 20% chance of living forever? Which is it? Either would be quite goddamned striking. I know that sound bite was taken out of context, but either way, it’s nonsensical – but it is what the public hears.

“The study found people who eat nuts tend to be thin and healthy.” Really? How interesting…

Just wanted to give you guys a glimpse of the bullshit machine in action. As recently put by James Thompson:

Most nutritional studies are observational, not experimental, and depend on questionnaires. There is always a nagging doubt as to whether every bacon sandwich and slice of chocolate cake will be faithfully reported, under the strain of recalling in vivid detail every lightly boiled cabbage and spoonful of cottage cheese.

Epidemiologists sometimes forget that people differ. Some are compliant boy scouts, some irresponsible spirits who don’t return questionnaires or follow instructions. Humans differ in intelligence and personality, but these considerations do not normally darken the door of diet epidemiologists. As far as they are concerned, people are what they eat, or become so after a decade of imprudent gluttony. Indeed, the meme “you are what you eat” seems to have had a great impact, despite being demonstrably false. Curious, the power of ideas, even stupid ones.

If any one wonders why we keep getting one pop diet fad advice after another, this is why. Medical science suffers from an over-reliance on observational studies. People trained to draw unwarranted conclusions from these studies however make up the backbone of the establishment, which is why we keep getting junk advice like this. As Thompson continues:

The other gripe among the cognoscenti? You read it here first. The sample sizes are too small, not followed long enough, and with high levels of sample attrition. Whoever you are, you cannot get round sampling theory. Samples of about 70,000 followed until death (with a proper link to death registers) will be required to identify even a few general patterns in diet which might account for a 5-10% increase in risk. If the studies are to mean anything, IQ, personality, sociological and occupational variables will have to enter the mix, and participants will probably have to be paid to stick to the course, and put up with random visits of inspectors looking in the fridge and the medicine cabinet. Count me out. So, although these correct and worthy researchers want controlled studies, they are not going to get them. Liberty will triumph over the food police.

These problems would in fact plague even randomized controlled trials, which I heavily advocate. In short, we continue to be utterly clueless which foods – if any – are useful to help ward off illness or extending life.

I will say this. Nuts are expensive. A decent sized can cost upwards of $5, which is one reason I don’t eat them anywhere as much I’d like, despite the fact that I love nuts (yes, I really do, all of you! :p). I’ll let you guys figure out the rest.

By the way, here’s the paper (abstract only, paywalled): “Association of Nut Consumption with Total and Cause-Specific Mortality

Previously: Trans Fat Hysteria and the Mystery of Heart Disease

Even George W. Bush Has Heart Disease

IQ and Death

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19 Comments

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  1. Mangan / Nov 22 2013 2:39 PM

    The study did have a huge sample size, and according to the abstract, the result was “after adjustment for other known or suspected risk factors”. Still observational, and one doesn’t know if the risk factors known or otherwise included things like IQ and SES, but your stricture that nuts are expensive and therefore a different population was involved needs more evidence to back it up. It’s not obvious to me that nut eaters would also be divided in other way,s such as by SES. In fact, mainstream advice for the past few decades has been to avoid them since they’re high in fat, and adherents to health doctrines (true or false) tend to be of higher SES and IQ.

    • JayMan / Nov 22 2013 4:44 PM

      @Mangan:

      The study did have a huge sample size, and according to the abstract, the result was “after adjustment for other known or suspected risk factors”.

      Isn’t that what they all say? 😉

      Still observational, and one doesn’t know if the risk factors known or otherwise included things like IQ and SES

      Precisely. And therein lies the problem.

      but your stricture that nuts are expensive and therefore a different population was involved needs more evidence to back it up.

      I wouldn’t be surprised if nut eaters are wealthier (they would have to be, given the price). However, that said, it’s worth noting that IQ is predicts lifespan independently from and stronger than SES.

      It’s not obvious to me that nut eaters would also be divided in other way,s such as by SES. In fact, mainstream advice for the past few decades has been to avoid them since they’re high in fat, and adherents to health doctrines (true or false) tend to be of higher SES and IQ.

      It would be worth looking at, especially in a way that controls for the obvious know important factor (IQ).

      The other obvious possible confound is race.

      I will note that there may be something to the nut thing. But naturally, this observational study is incapable of proving such.

      Thanks for commenting! 🙂

    • Anonymous / Nov 24 2013 3:21 AM

      when all “confounds” are controlled for and the sample is large, then it’s unlikely correlation doesn’t equal causation. smoking and lung cancer is an example. the odds ratio is simply too high to be mere association.

      “In fact, mainstream advice for the past few decades has been to avoid them since they’re high in fat, and adherents to health doctrines (true or false) tend to be of higher SES and IQ.”

      for at least the past 20 years it’s been the official doctrine that mono-unsaturated fat is healthful, and that other fats are un-healthful over a threshold easily crossed by most americans. stearic acid and omego-3s from animals are an exception.

      the inuit eating a traditional diet have no issues with heart disease, but the composition of fat in wild animals is much different from that of domesticated animals.

    • JayMan / Nov 24 2013 7:33 AM

      @Anonymous:

      Is it all the confounds, or all the ones they can think of? That’s the problem with observational studies. It just doesn’t work the way you’re saying.

      Better still, one key variable I’m pretty certain wasn’t controlled for: IQ.

      As for hunter-gatherers on traditional diets, one has to remember that such people have high youth and young adult mortality rates. The ones that make it to old age may be the toughest of the tough, so it’s not actually a fair comparison.

    • Anonymous / Nov 24 2013 11:33 PM

      right. it’s always the one’s “they” can think of, but if smokers are 10x more likely to contract lung cancer you’re wasting your time looking for confounds imho. why? i’d have to think about it. the same goes for alcohol and throat cancer. drinkers who’ve never smoked have an odds ratio of 3 or 4 compared to never smoked, never drank. (and i’m a heavy drinker.)

      nuts are fatty but the fat of most nuts is predominately mono-unsaturated.

      seal oil is the official explanation for why the inuit aren’t dying from heart disease. i did read that athero was found in inuit mummies though.

      “As for hunter-gatherers…”

      this isn’t the case always. life expectancy in the solomon islands is now 74. http://en.wikipedia.org/wiki/Tsiman%C3%A9_people#Health. paul theroux, in his happy isles of oceania, meets a 100 year old man in the trobriands. even the very aged in these cultures die from infections, like tuberculosis, not from cancer or heart attacks or strokes or kidney failure or diabetes.

      you may argue over the risk factors for ischemic heart disease and athero generally, but i don’t think there’s any arguing that some have risk = 0. if you’re bp is 100/60, your hdl is > 70, your ldl is < 100, you're active, you're anti-diabetic, and you're thin your risk is 0. you will never have a heart attack.

      and all of these can be realized just by doing what alexander selkirk did or what tom hanks did in cast away. "when diet and exercise aren't enough…" BUT THEY ARE!

      argue and nitpick tell the cows come home. it's not about details. it's too complicated.

      the diseases of civilization aren't a fiction, aren't just the result of differences in mortality. with the exception of antibiotics and vaccines and plumbing civilization has almost nothing to offer in terms of increased life expectancy. and until the last 100 or 200 years life expectancy at birth in the civilized world was less than for man's pre-agriculture ancestors. (for this see pandora's seed).

      each piece of evidence on diet, exercise, sleep, stress, etc. and health by itself is meaningless, but all of the evidence points in one direction—the way people live today is not as nature intended. with vaccines, antibiotics, antihelmenthics, the best advice for long and healthy life is live like a savage.

    • JayMan / Nov 25 2013 8:52 AM

      @Anonymous:

      right. it’s always the one’s “they” can think of, but if smokers are 10x more likely to contract lung cancer you’re wasting your time looking for confounds imho. why? i’d have to think about it. the same goes for alcohol and throat cancer. drinkers who’ve never smoked have an odds ratio of 3 or 4 compared to never smoked, never drank. (and i’m a heavy drinker.)

      Strictly speaking, I’d say no. But yes, it would be something to give a closer look, yes.

      They didn’t even find something even remotely to being that strong with nuts.

      Look, correlational studies are incapable of demonstrating causation. Even “genetically informed” ones, which come the closest to being able to do this, have their limits.

      this isn’t the case always. life expectancy in the solomon islands is now 74. http://en.wikipedia.org/wiki/Tsiman%C3%A9_people#Health. paul theroux, in his happy isles of oceania, meets a 100 year old man in the trobriands. even the very aged in these cultures die from infections, like tuberculosis, not from cancer or heart attacks or strokes or kidney failure or diabetes.

      You’re not getting me. Sure, they are certainly old individuals, even some that are very old. But how many had to die for those strongest individuals to survive? Most hunter-gatherers lose a considerable number in childhood/early adulthood.

      and all of these can be realized just by doing what alexander selkirk did or what tom hanks did in cast away. “when diet and exercise aren’t enough…” BUT THEY ARE!

      Except they’re not. Most every true controlled test of these has failed. These things just aren’t effective.

      the diseases of civilization aren’t a fiction, aren’t just the result of differences in mortality. with the exception of antibiotics and vaccines and plumbing civilization has almost nothing to offer in terms of increased life expectancy. and until the last 100 or 200 years life expectancy at birth in the civilized world was less than for man’s pre-agriculture ancestors. (for this see pandora’s seed).

      You just demonstrated that you don’t understand the concept. There’s a huge difference between life expectancy at birth and life expectancy at age 5 or 15, the former of which pre-agricultural societies fare poorly.

      each piece of evidence on diet, exercise, sleep, stress, etc. and health by itself is meaningless, but all of the evidence points in one direction—the way people live today is not as nature intended. with vaccines, antibiotics, antihelmenthics, the best advice for long and healthy life is live like a savage.

      Even in toto, the “evidence” is largely meaningless. This is because the overwhelming bulk of it comes from worthless observational studies like the one here. All the best evidence we have suggest that there is little external modification can do to alter these outcomes.

      For the record, I’m not completely discounting the connection to an agricultural lifestyle being behind certain diseases, like heart disease. But you need to make a much better case than you’re making here.

    • Anonymous / Nov 24 2013 11:45 PM

      i wish these had an edit. that should have been “till the cows…” and “antihelminthic”.

  2. Canadian Friend / Nov 22 2013 2:50 PM

    Maybe people who eat a lot of nuts tend to do other healthy things such as avoiding processed foods, eating more fruits and vegetables, maybe they exercise more, avoid smoking or drinking too much et cetera…

    Maybe they visit their doctor more often, maybe they know how to relax better than other people and suffer from less insomnia et cetera…

    Maybe they are people who are well informed on what healthy habits are and they apply this in their lives…

    and maybe that explains the 20% decrease in mortality ( not “improved” mortality)

    The eating of nuts might simply be one of many “symptoms” ( for lack of a better word, French is my first language, the right word does not always come easily to me ) of a more healthy lifestyle and not the magic health food it seems to be.

    • JayMan / Nov 22 2013 4:49 PM

      @Canadian Friend:

      Maybe people who eat a lot of nuts tend to do other healthy things such as avoiding processed foods, eating more fruits and vegetables, maybe they exercise more, avoid smoking or drinking too much et cetera…

      Yes, maybe. It may be a lot of things. That’s the problem with observational studies.

      The eating of nuts might simply be one of many “symptoms” ( for lack of a better word, French is my first language, the right word does not always come easily to me ) of a more healthy lifestyle and not the magic health food it seems to be.

      Precisely!

      I will note that, for the record, it’s unclear to what extent “lifestyle” is responsible for longevity and health, and for these things connection with IQ. It is possible that much of it – indeed, perhaps the majority, is due to intrinsic healthiness. That is my suspicion at present (see this Twitter conversation with Education Realist).

  3. chrisdavies09 / Nov 22 2013 6:10 PM

    Lol, I saw this news story about nuts earlier today on the BBC news website, and immediately I thought of Jayman warning about correlational, observational, and self reported studies..

  4. Staffan / Nov 23 2013 8:10 AM

    It’s likely researchers don’t like the idea of some people being unintelligent and having poor health simply because they’re second rate, having a high mutation load or something like that. After all, they are largely White and Asian upper middle class people and most of them are no doubt very liberal.

    • JayMan / Nov 23 2013 10:50 AM

      @Staffan:

      You’re likely quite right.

    • JayMan / Nov 23 2013 12:02 PM

      @Staffan:

      I will also note this talk by Kevin Mitchell, which plays into the point you mentioned about genetic load, which I discussed back in my post IQ and Death:

  5. Avery / Dec 9 2013 6:28 AM

    When I was a kid, we always got nuts from our trees. 🙂
    For what most people pay for chocolate, chips, and soda, they could afford nuts. On the converse, it is likely that nut-eaters are forgoing other snacks, like chocolate. And nuts do carry fewer calories per volume than chocolate. I find it hard to feel full on nuts.

    Still, I don’t think it’s a terrible idea to try to imitate the habits of people who are succeeding at the things I want to do.

    • JayMan / Dec 25 2013 11:12 PM

      @Avery:

      Probably not necessarily the worst idea, but not exactly guaranteed to be fruitful. No more than emulating Tiger Woods or LeBron James would necessarily make you great at golf or basketball, respectively.

  6. Steve Johnson / Mar 6 2014 2:15 PM

    Here’s some dead certain evidence that any effect is telling you about the health of the type of people who eat nuts vs the type of people who don’t:

    Peanuts aren’t nuts and yet people who eat peanuts show the same reduced mortality.

    The obvious explanation is it that people think peanuts are nuts and so there is no difference between the group of people who eat peanuts versus the group of people who eat actual nuts and that this is the key difference.

    This suggests a simple study – break out exclusive peanut eaters versus those who eat nuts. Quiz all the groups on whether or not peanuts are nuts. The “yes, peanuts are nuts” groups should be about equally healthy

    The “no, peanuts are legumes” group should be healthier (being higher IQ). If there’s a real health benefit to eating nuts then the nut group will be healthier than the matched on peanut knowlege peanut eating group.

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