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Healthy By Default's avatar

I just read the linked article "Should Modern Humans Eat Like Hunter-Gatherers?". The article is an argument against using the robust health of hunter-gatherers as evidence that any of their lifestyle choices (particularly diet) have a positive impact on their health, because of survivorship bias. Basically child mortality rates are quite high in hunter-gatherer societies (which is true), so it follows that the adult population has been selected for the healthiest individuals (or the least susceptible to common causes of childhood mortality). Intuitively, this strikes me as incorrect because I would guess that the sorts of things that would kill a child would not also make that child susceptible to chronic diseases in old age. I could be completely wrong but that's just my first intuition. Curious to hear your thoughts.

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John Lawrence Aspden's avatar

Yes I think I largely agree, survivor bias will make people look healthier, but it shouldn't be completely eliminating obesity and heart disease, say, unless we're actually expecting everyone who's obese or has high blood pressure to be killed before we get to measure.

Of course it's not just childhood diseases, adult males in a state of nature get into deadly fights, women die in childbirth, people fall out of trees and get bitten by snakes and infested by parasites. The real world is a deadly place, and wild animals are beautiful because they have hard lives.

For a mental model, imagine that a mad philosopher takes a typical US town and forces everyone to run a marathon at gunpoint, shooting anyone who stops running.

At the end of the day, we'd expect to have a much smaller, but much healthier population.

But the actual details depend on how good a shot the philosopher is, how likely his bullets are to maim rather than kill, and the illnesses we're interested in.

Knee problems are likely to be completely fixed, statistically, but there may be little to no effect on anosmia rates.

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Nick's avatar
Sep 9Edited

"... the sorts of things that would kill a child would not also make that child susceptible to chronic diseases in old age"

What is the argument for this? Nearly all chronic diseases have a fundamental immunological component, and the overwhelming majority of infant and child mortality is immunological in nature. There is very plausibly a direct point of interaction between the two.

Nevertheless, I demonstrated in the article that even traditional populations eating ancestral diets have pretty much the same rates of ASCVD that can be found in the US population, so the point is moot with respect to ASCVD anyway.

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John Lawrence Aspden's avatar

Nick, would you be brave enough to try 'your normal diet plus an unreasonable amount of high-linoleic sunflower oil' for a bit and see how it makes you feel? Or maybe something like linseed oil that has more omega-3s in it if you think that's important?

I should do it myself but I am too scared.

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Scott Anderson's avatar

tried reading his stuff (again - used to run into him on twitter) - tough to do. he writes like a 12 yo. oozing his bias from the jump and a 'liberal' dose of ad hominem along the way. maybe he makes good arguments. . . but I'll never know. N of 1 I have found considerable improvements in health from greatly restricting the dietary PUFA. No need to reintroduce industrial fats. BTW - if vegans want to avoid PUFA, easy peasy - coconut oil.

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John Lawrence Aspden's avatar

I do think it's important not to be misled by style. I want to know the truth, and if people are giving me new tools to help me think then I try not to be deterred by surface stuff.

In this particular case I really do think that Nick's got interesting things to say to us, and he explains his thoughts well.

I'm sure there's a problem. I'm pretty convinced there's something evil in modern food, and I think it's probably PUFAs, but there are plenty of things that don't quite fit with the idea.

We may be wrong. And if we are wrong, it's very much in our interest to work that out and find out what the real problem is.

At the very least, by helping me understand the mainstream position he shows me why "PUFAs bad" isn't just obvious to everyone in medicine!

It does seem to be obvious to lay people. More and more I'm saying to people "Avoid the polyunsaturated abomination, oh my brother" and they're saying "Oh yes, I've been avoiding vegetable oil for a year or so now."

I'm not necessarily reassured by this. If we're starting a popular movement against vegetable oils we really should be sure vegetable oils are actually bad news.

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Scott Anderson's avatar

'We may be wrong.' Prudence requires that we always allow for this possibility. But the chances that I'm going to EVER obtain an understanding of the relevant literature to surpass @TuckerGoodrich is basically nil. Just not smart enough OR have the time to invest. My reading of Nick is that he isn't really interested in persuasion (and did I read that his wife is employed by big soy?). Anyway, '. . .we really should be sure. . .' Advisable, but metaphysical certitude is probably not a realistic goal. Counter question, what's the DOWN-SIDE of eliminating industrial oils (in the vanishingly small chance that we're mistaken)?

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John Lawrence Aspden's avatar

> But the chances that I'm going to EVER obtain an understanding of the relevant literature to surpass @TuckerGoodrich is basically nil. Just not smart enough OR have the time to invest.

No me neither, but that's also true of all the medical types who are really into studies.

I'm more interested in what we can work out without playing the study-wrangling game, which seems kind of hopeless, for reasons.

Nullius addictus iurare in verba magistri, quo me cumque rapit tempestas, deferor hospes.

Once we have plausible looking mechanisms, then we can 'do studies' to find out if they're true.

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John Lawrence Aspden's avatar

> Counter question, what's the DOWN-SIDE of eliminating industrial oils (in the vanishingly small chance that we're mistaken)?

Probably nothing! Maybe a slight increase in the risk of CVD if they really are helpful. Not enough of a risk that I could actually bring myself to care.

The real risk is that by blaming seed oils we miss the real problem.

It's not a vanishingly small chance. Plenty of very convincing looking theories have just been flat wrong. I am convinced 'on balance of probabilities', I am not nearly convinced 'beyond reasonable doubt', let alone to 'vanishingly small chance' levels.

I'm not worried that we're wrong because that's the epistemically virtuous thing to do. The Lord knows that I am not a virtuous man.

I am worried that we might be wrong because I think that we might be wrong.

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Scott Anderson's avatar

ok, well, I applaud your willingness to wade thru his, uh, writing in the pursuit of truth. Would you care to summarize the single most compelling argument that he makes that we PUFA sophists are wrong? <and I'll admit that 'vanishingly small' is a bit of hyperbole>

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John Lawrence Aspden's avatar

So the one that's currently giving me most conniptions is definitely the 'survivor bias' thing, which means I'm much less confident in 'healthy pre-modern populations', which kneecaps *a lot* of my arguments. And I'm kicking myself for not having realised it earlier.

So be it. That which can be destroyed by the truth should be.

There was also a good discussion of SFA/PUFA trials for heart disease, which if it all checks out is in the opposite direction I'd expect. I can probably explain that but I feel uncomfortable having to.

His attempt to show that lipid peroxidation doesn't matter actually convinced me that it does, more than anything of Tucker's, precisely because it's coming from someone trying to show the opposite. (you can prove what you like with studies, but if you try to prove something and have trouble that's interesting).

The antagonistic pleiotropy thing strikes me as very good, but it 'proves too much', I think, and it wasn't an idea I'd encountered before, so I'm going to have to think about all that.

And there's lots more that I haven't had time to process yet.

I actually enjoy Nick's style. I'm a combative man myself, and so I don't mind it in others. A man should say what he thinks. I think a reluctance to call bullshit is half of what's wrong with academia.

But what I really like is that it's giving me an insight into how it's possible to believe 'PUFAs good'. A man who can't even see where the other side are coming from has no business taking a position.

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Scott Anderson's avatar

Re: survivor bias. Just re-read WA Price's Nutrition and Physical Degeneration. Cannot escape the conclusion that 'healthy' pre-modern pops become way less so when introduced to 'modern' foods. No evidence that the subsequent degradation in population health was due to change in infant mortality. Suggested reading. (note: if I'm misunderstanding Nick's argument here, pls elucidate)

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John Lawrence Aspden's avatar

> N of 1 I have found considerable improvements in health from greatly restricting the dietary PUFA.

Yeah, me too! And many other such cases. But it could all be from getting rid of processed food generally, I mean everyone thinks that's a good idea. My money's on 'there is a particular ingredient that we think is safe but which is not in fact safe', and PUFAs look like the first place to look.

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Scott Anderson's avatar

'. . .from getting rid of processed food generally.' Not in my case. Went low-carb/keto/carnivore 11 years ago to good effect. However, some things refused to resolve until I ditched the PUFA 3+ years ago.

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John Lawrence Aspden's avatar

Excellent evidence! But was your 'low-carb/keto/carnivore' free of processed crap full of chemicals?

What would be really convincing is if someone noticed a difference between 'no-PUFA diet' plus pure linoleic acid and 'no-PUFA diet', but none of us is brave enough to actually try that, because we all think linoleic acid is the anti-Christ.

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Scott Anderson's avatar

yup. pretty much. then (as now) cooked/ate 95+ % at home. whole foods, little/no ingredient list (beef, chicken, pork - had to drop the chicken and pork post PUFA). Used to eat a LOT of bacon and $0.97/lb Smithfield pork shoulder in the crock pot (there a reason they're giving that stuff away!) as well as roasted chicken from the market. Now those just look like canola oil. Have bought B Marshall's Firebrand low PUFA pork, but, $18/lb.? Yowza!

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John Lawrence Aspden's avatar

Oh nice, bravo, you should write that up! I'll post your write up here if you like.

The pork thing is weird. American pork fat seems to be something like 28% linoleic acid, which is just freaky. Those poor pigs. What on earth does it taste like? It should be practically a liquid. No wonder 'studies show' lard is baaad.

Brad's got his down to 6%, but that's actually the same as the cheap-ass cooking bacon in my local Sainsbury's apparently. Not that I'll eat that, because I won't eat anything I'm not reasonably confident hasn't been made of misery.

Even 6% seems way high.

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