I've been watching for several years now (I adopted the diet myself in 2010), and all of the negative critiques tend to fall into (a) critiques from non-experts, (b) critiques from experts in unrelated fields, (c) health experts who agree that his recommendations have merit, but that they're impractical for the general public to follow.
I produce for you a book written by a relevant expert with ~2.5 times as many references as The China Study (2034 vs 758) who advocates eating an ancestral diet (lean unprocessed meat/fish, fruit, nuts, vegetables/root vegatables) (1). A list of individuals with relevant graduate degrees who more-or-less agree with him can be found in this list of speakers at a paleo conference he spoke at. His recommendations are at least as similar to the recommendations the Mayo clinic returned for me as Campbell's.
That is, I can make a symmetrical argument for a significantly different diet (2), complete with experts and evidence and stuff.
So, to address your questions directly: you should believe that nutrition is a young and complex field, and therefore shouldn't have everything all figured out; my take is that you may do well to replace grains with root vegetables, since that's something everyone agrees is good (plus they're really tasty!); this isn't good enough to inform your dietary choices because I just used a symmetrical argument for a diet that has nonnegligible discrepancies with the diet Campbell recommends; and I don't know how to dig out a signal that experts, to my knowledge, haven't managed to dig out without becoming an expert.
(FWIW, I spent about 5 years as a vegetarian, followed by 1.5 years doing the paleo thing, and now subsist entirely off DIY soylent, which combines the virtues of deriving all its protein from animal sources and being processed.)
(1) Interestingly, Campbell's and Lindeberg's diets can be eaten simultaneously, and this intersection is 100% in-line with what the Mayo clinic recommended me. The difference is that Campbell allows grains and beans, and Lindeberg allows (unprocessed) lean meats, fish, and eggs.
(2) Again, there's substantial overlap, but also substantial disagreement: Lindeberg, for instance, observe the Inuit derive something like 98% of their calories from animal sources and are virtually untouched by Western disease, and concludes that very high consumption of (unprocessed) animals is perfectly fine, whereas Campbell claims that humans should eat minimal amounts of animal.
the Inuit derive something like 98% of their calories from animal sources and are virtually untouched by Western disease, and concludes that very high consumption of (unprocessed) animals is perfectly fine
Just how genetically isolated are the Inuit?
I am thinking of things like the evolution of adult lactose tolerance, and wondering if what's good for the Inuit might be different from what's good for the rest of us. I'd expect the ability to consume large amounts of meat without ill effects would be pretty powerfully selected for, in an environment where nearly all calories come from meat.
The selective pressure on being able to digest lactose as an adult is stronger than the selective pressure to not develop heart disease from eating too much meat, since the former kills you before you can reproduce. Lindeberg claims that humans have sufficiently recent common ancestry that, in absence of the kill-you-before-you-reach-childbearing-age selective pressures, we're able to generalize from group-to-group fairly well. Non-Inuit probably do worse than Inuit on Inuit diets, and bool is_Inuit is a useful input in a program to produce an optimal soylent blend for someone, but the selective pressure isn't strong enough for the Inuit to be mostly devoid of heart disease [1] simply because it was selected for.
Also, many other hunter-gatherers from all over eat large amounts of meat (though as much as the Inuit) and are just as devoid of Western disease as are the Kitavans, who consume relatively little, which supports the hypothesis that Inuit aren't mostly devoid of heart disease because they're genetically unusual.
[1] IIRC Inuit do suffer from slightly more Western disease than Kitavans (most calories from plants), but not by a very impressive margin.
And also, where the Inuit live it's frigging cold, and maybe a protein-rich diet like theirs is only healthy in cold weather (and a protein-poor diet like pre-WW2 Okinawans' is only healthy in warm weather) for some reason or another. (Anecdotally I tend to eat much less meat during the summer, which may or may not have something to do with that.)
Separate topic!
(FWIW, I spent about 5 years as a vegetarian, followed by 1.5 years doing the paleo thing, and now subsist entirely off DIY soylent, which combines the virtues of deriving all its protein from animal sources and being processed.)
What I find alarming about soylent-like diets is the idea that you can completely capture human nutritional needs as a table of micronutrients quantities to fill, and then go out and source those individual micronutrients, combine them, and drink.
Aren't you discounting the importance of the configuration of these micronutrients as they arrive in their natural packages? That is, you can certainly decompose an apple into fructose, fiber, vitamins, minerals and water (and etc), but I find it hard to accept that shopping for these individual components, blending, and pouring down your throat is just as good (or better) than eating the apple. Surely we do not completely understand everything nature has done in building us this apple.
This discussion has already happened at great length here.
To summarize my stance: there's risks, but considering that everyone I've read on discourse.soylent.me has had positive results across the board, from body composition to semen taste. I get noticeably improved mental clarity (along with getting so lean I'd be scared I was undereating if I didn't know precisely how many calories I was eating and clearer skin), which makes me willing to accept those risks. Also, because soylent might be safe and come with a load of benefits, there's data-generating value in taking individual components, blending, and pouring them down my throat to see if anything bad happens. (Julia Galef on tradition as it pertains to social systems, that happens to be applicable here.)
But I'm not very worried; I have trouble imagining a food that has positive effects of "improve body comp, improve mental clarity, clear skin, make semen taste good" and no known negative effects and is biochemically plausible to actually be bad in the long term. Certainly not impossible, but not very probable, I think.
Makes sense, thanks for the link and your summary.
I've taken a keen interest in soylent but am happy to let others beta test long-term effects for me before I give it a shot :)
FWIW, the way soylent people describe their results is more or less how I describe what happened to me when I adopted a whole food plant-based diet (the "china study diet"): BF% dropped/I got leaner, various body odors improved, huge reduction in acne, became a morning person, was able to stop taking ADHD meds, and felt no negative effects at all. Except for maybe I now have so much energy I just had to pick up distance running and ultimately hurt my ankle. :P
I'm specifically trying to avoid weighing the actual science or studies myself, because I don't think nutrition is linear enough for me to just dive in and read contradictory studies and start making informed decisions about my diet. So, all I'm really electing to do here is try to valuate experts. In that vein...
I produce for you a book written by a relevant expert
According to Wikipedia the author of that book, Staffan Lindeberg, is "M.D., Ph.D., (born 1950) is Associate Professor of Family Medicine at the Department of Medicine, University of Lund, Sweden. He is a practicing GP at St Lars Primary Health Care Center, Lund, Sweden."
I agree he's a health expert. I even agree he's more qualified to judge nutrition science than me. But shouldn't a nutrition scientist like Campbell be even more qualified to evaluate nutrition literature than a professor of Family Medicine?
He may be right, and Campbell completely wrong but I don't see a good way to figure this out for myself unless, say, someone can make an extremely good case that Campbell is either a rogue in nutrition science, or that nutrition science shouldn't be trusted. Getting to your next point...
So, to address your questions directly: you should believe that nutrition is a young and complex field, and therefore shouldn't have everything all figured out
Why wouldn't nutrition scientists studying nutrition come to a similar conclusion about how young, murky, and complicated nutrition is? Shouldn't they on average know this better than anyone and only make very careful and strongly supported recommendations?
If you can't trust nutrition scientists to judge the literature properly, why should you trust scientists outside of the field or layman attempting to dive into the field would be better?
Why wouldn't nutrition scientists studying nutrition come to a similar conclusion about how young, murky, and complicated nutrition is? Shouldn't they on average know this better than anyone and only make very careful and strongly supported recommendations?
They have very strong incentives (ie earning money and building a career and having patients) to pretend to be certain. People don't want to pay for honest but vague guesses.
If you can't trust nutrition scientists to judge the literature properly, why should you trust scientists outside of the field or layman attempting to dive into the field would be better?
You shouldn't really trust scientists outside the field to talk about the entire field of nutrition but insofar as experts in older and more reliable fields like chemistry or biology disagree with specific nutritional claims you should probably agree with the actual scientists.
They have very strong incentives (ie earning money and building a career and having patients) to pretend to be certain. People don't want to pay for honest but vague guesses.
I would expect consensus (or the lack thereof) is an important signaler for exposing this kind of bias?
Maybe? It's a lot safer to be certain if you're saying the same thing as the consensus. Then at worst you can say you had the same opinion as a lot of other providers.
Lindeberg is a nutrition researcher (conducts studies, co-authors papers) coming from a medical background, which makes him just as much an expert as a nutrition researcher coming from a biochemistry background.
Why wouldn't nutrition scientists studying nutrition come to a similar conclusion about how young, murky, and complicated nutrition is and only make very conservative, very strongly supported recommendations?
We can measure how much a field has progressed by its predictive power, and nutrition is already making concrete predictions with high confidence. Not a lot, not with the confidence of, say, Newtonian mechanics but, given how very much literature there is and how very complicated things are, the level of consensus across researchers who are coming at the problem from disparate-but-legitimate approaches (e.g. biochemical, evolutionary) is sufficiently impressive that I do trust them to judge the literature properly. Humans are biased, so it's unsurprising that we don't yet have a consensus as broad as, say, existence of the golgi apparatus, but the world looks exactly as we'd expect it if nutrition scientists were doing good work in a complicated field.
To summarize: Lindeberg, like Campbell, is an experienced nutrition researcher with impressive and relevant credentials. Nutrition is a young and complex field, so there's no broad consensus about everything—although there is broad consensus about some things—but nutrition scientists are doing a decent enough job of figuring things out that I trust them to judge the literature properly.
Lindeberg is a nutrition researcher (conducts studies, co-authors papers) coming from a medical background, which makes him just as much an expert as a nutrition researcher coming from a biochemistry background
Am I asking for too much by insisting on a nutrition researcher from a biochemistry background to refute Campbell? Or are you saying they can both be right within the framework of their fields?
To summarize: Lindeberg, like Campbell, is an experienced nutrition researcher with impressive and relevant credentials. Nutrition is a young and complex field, so there's no broad consensus about everything—although there is broad consensus about some things—but nutrition scientists are doing a decent enough job of figuring things out that I trust them to judge the literature properly.
I am moved enough by your insight and your persistence to give Lindeberg's book a read. :)
Largest effects with the smallest error bars around them: Processed meats bad, fruits and vegetables good, fish and nuts good.
Everything else is significantly smaller effect size or large error bars AFAIK.
All we have for that are questionnaires, not on the same level of evidence as the others. AFAIK https://archinte.jamanetwork.com/article.aspx?articleid=1819573
I know very well a registered dietitian who deeply knows her stuff. She's explained quite a lot to me, and given me considerable knowledge (it helps that my field is chemistry, and while biochem is different than what I do it's not completely alien).
Unfortunately I can't say much about nutrition in one single post. Like so many things, it's a really complex and rich science and to really know something about it would take years of education on the subject. As you may imagine, everything comes with lots of exceptions and qualifiers. My recommendation if you really want to learn this stuff is to talk to a registered dietitian (any quack can call themself a neutritionist, but RD is a protected title), or read recent academic textbooks (NOT popular books) on nutrition.
About the subject matter in the main post, from my knowledge, meat and heavily processed foods tend to be more in the territory of things that are worse to eat a lot of. I can pretty certainly say it's true that many people would do better to eat considerably less of that stuff than they do.
Speaking from my area of expertise now, I'll say that it's pretty silly from a thermodynamics standpoint to eat meat. You can do fine as a vegetarian, and raising plants to eat is significantly more energy efficient than raising plants to feed animals to eat. Animal raising leads to a considerable amount of energy waste, as well as material pollution. I don't have the numbers on hand, but it's enough to be a significant factor. So what do I do? I don't eat meat very often.
(6.) The natural world can be complicated, and scientists have limited tools to investigate and a lot of incentive to oversell.
It is difficult to arrange RCTs for nutrition -- and so you must be very careful. My advice is to engage with their actual citations.
(6.) The natural world can be complicated, and scientists have limited tools to investigate and a lot of incentive to oversell.
Agree that the world is complicated. Could you go into more detail about incentive to oversell? Do you mean they need to promise groundbreaking results to close funding?
Scientists have to market themselves to earn kudos in their field, and get grant money. This isn't bad in and of itself, but there are usual marketing incentives here.
Diet doesn't seem to be a one size fits all proposition.
Different people have different metabolisms and different gut flora profiles.
It's more likely that everyone has a perfect diet that would be just right, but just for them. The particular bacteria in your gut might be very adept at turning lactose into calories, and not so in others. Things like this would help prescribe foods, and in certain cases where your flora are too helpful, maybe a fecal transplant from a skinny person.
When we have enough calories to meet our needs every day, we have to find ways to help people whose only way to stay thin is to walk around feeling starved, which used to be adaptive but now isn't.
D'oh! I thought it meant some kind of special honor. Does it at least mean "was granted tenure and was not fired"? That's not useless information, I guess.
Yeah, it's generally reserved for tenured professors that retired with the title of "Professor" (instead of "Associate Professor" or "Assistant Professor"). In general, after you get the title of "Professor", there aren't any more promotions to get.
My view of nutrition is basically option 2. "Nutrition science" as it exists today seems to be primarily an attempt to study subtle, complex effects using small, poorly-controlled samples. There are basic facts about nutrients that are fairly well supported, but I have never become convinced of the superiority of any "diet" based on the supposed evidence for it.
I think the answer is mostly two, with a little side of four. Nutrition science is very difficult to perform correctly, because of the difficulty and cost of randomized controlled trials of diets. In particular, the China study was not controlled, and it was performed via surveys (which have a reputation for being inaccurate in diet studies). Added to that is the fact that food isn't really about food. It's deeply intertwined with our sense of personal identity and culture, and that leaves you with many researchers stretching their relatively weak evidence a little bit further than is warranted. Once you get as far removed from the actual science as recommendations from the FDA or Harvard School of Public Health, there is virtually no room left for nuance, and they are already making recommendations from a public health perspective, which is not the perspective you seek.
With respect to confirmation bias, I suspect there is some of that going on. Specifically, you say, "There are lots of people who are PhDs of exercise, anthropology, or economics who criticize his recommendations, but I have a hard time finding a mass gathering of nutrition scientists coming out of the woodwork to shoot down his recommendations." There are probably not "mass gatherings of nutrition scientists" who disagree with the China Study, but there are mass gatherings of experts in medicine and various biological fields (and maybe the odd nutrition scientist) who would probably disagree with the China Study. Googling "paleo conference" I could easily find several such mass gatherings. So you aren't wrong, but you are implying more with your selection of outsider expertises than is warranted (exercise, anthropology or economics, rather than doctors, biologists, etc.).
With respect to the object-level consideration, I recommend you read Stephan Guyenet's recent series of articles on meat Is Meat Unhealthy?, which considers both positive and negative factors of eating meat. He is not a nutritional scientist (he is a neurobiologist), but he is by all appearances a careful scholar. You can read the summary first if you want to see his ultimate conclusions, which don't strongly support either the "vegan" or the carnivorous sides of the debate.
However, with respect to the China Study itself, he only touches on it in this series thusly:
The China Study
The China Study was a massive ecological study relating diet and lifestyle to chronic disease risk in China. It has been invoked by researcher and vegan diet advocate Colin Campbell to support the idea that animal foods promote cardiovascular disease and cancer, even in the small quantities that were typical of the regions studied. After having reviewed the study data, the publications based on it, and the various commentaries on it, it appears relatively clear that the China Study does not support the conclusion that meat consumption is associated with cardiovascular disease or cancer risk (17, 18, 19, 20, 21). Everyone seems to agree on that, except Campbell and certain other vegan diet advocates. I won't discuss the China Study further.
And elsewhere has criticized it on methodological grounds (e.g. here)
Reading a little bit, I'm reminded that there's more than one party involved here.
Now, I'm no scientist, but you don't have a diet without a person. We can correctly assume that you can't go on without one or the other. Coming from this way, we can make an rather simple observation that not every diet is the same, and that not every person is the same. While the diet part is extremely important, it's not as important as the person, as ultimately the diet is digested inside the person. Considering every person is different, would it be a far stretch to say that their diet should be different, too?
This is a simple observation I made just now. I've noticed an dispropronate weight on people's diet. It's not entirely incorrect - there is some common ground between people. But people are micro/macro-different, healthy is still a vague term (some sort of close-to synonym with nutriential value) and even my observation might not include all of the parties involved. But I think it's a good general look in the right direction.
So, if we were to think about nutrition, we should first clear the things with the largest weight so we have a good base to stand on. And we incrementally build the pyramid from there.
Why doesn't your list of "things I've considered" include an option like, "Nutrition science is real science, and Campbell's work is correct"?
Given "I adopted the diet myself in 2010", I assume that's the option that the poster implicitly favors, and the question is why more people do not do the same.
and the question is why more people do not do the same
I find the whole idea of diets, as normally presented, weird. There is a cultural, ethnic and family tradition of what meals to cook and eat for me. This is part of my identity and lifestyle. The first issue is that diets do not even talk about meals, they talk about ingredients: meat, vegetables etc. are ingredients, a peas and chicken breast casserole in so-and-so sauce is a meal. So unless diets are meant for people who were always, no offense, eating boring as a family tradition, in a meat-and-two-vegs style, diets are weird. I am not eating meat or potatoes, they are merely the ingredients of the meals.
The same way you don't eat "flour" or "wheat" or "grains" or "carbs", you eat e.g. Italian sourdough bread from so-and-so bakery, so diets that talk about flour/wheat/grains/carbs get the inferential distance, the mental map completely wrong. They require a huge cognitive effort and facing unfamiliar and non-obvious thinking.
I mean, the point is here that diets want you to think bottom-up, you want to eat X ingredients and look for recipes for them. This is a huge distance from the usual, normal thinking, which is top-down, that you eat meal Y and buy whatever ingredients the recipe requires or buy the meal ready in a restaurant or somewhere and don't even know the ingredients. (I can identify the cucumbers in my restaurant ordered Stroganoff but not sure if the other tidbit is mushrooms or what, example.)
Add to it the factor of finding out the ingredients in everything you did not cook yourself, from your aunt's cake to the street hot dog (brown-bagging every work lunch is another "boring guy" territory to me, it is just too "anal" to not eat random things that are offered but carry your food supply the same way an astronaut carries oxygen supply).
Instead of all this weirdness, I manage my weight with 1) cutting down on vices, snacks, sugar soda (just drink coke zero) etc. stopped boozing etc. 2) intermittent fasting, as not-eating is never cognitively weird and probably autophagy is one of the most important parts of dietary health (read Eat Stop Eat). This is not an easy process either, I think I got to the point where the calories are right, so now the potential issue is micro-or macronutrient deficiencies.
My larger point is that any specific diet is merely an instance of the more generic class of being on diets, on being choosing and conscious about eating instead of drifting in a largely unconscious family and ethnic tradition, and I find that cognitively difficult and weird. However, it is a classic case of being the average of the five people you spend the most time with. If diets in general are normal in your subculture or culture, it is easy to adopt one, so basically your friends going pale can help you go vegan because they both are subsets of the whole choosy and conscious eating thing. If diets sound like some weird new sissy fashion to most people you spend time with and they make fun of "reform kitchen" and everybody just drifts in their ethnic and family tradition or whatever can be bought on the street, you will also find it hard.
(I should also say I am not longevity oriented because I find it hard to fill out time with goals. But the quality of the 60-65 years I roughly expect to spend alive does matter, hence the experiment with things like intermittent fasting.)
Disallowing certain ingredients does not restrict one's range of recipes that much. That is how some traditional cuisines came to be, in countries where the local religions forbid certain types of foods. For example Islamic countries. They just found ways around pork and alcohol, and judging by the popularity of Middle Eastern cuisine, it's not as if they're any worse off for it. The same thing happened recently with vegetarian or vegan food. So many recipes are explicitly branded as vegan that it's not difficult for a vegan person to find things to eat.
I find myself at the midpoint of the two approaches to eating. On one hand, I don't have any specific ingredients which I altogether avoid for other reasons than the fact that I absolutely hate their taste or find the idea of them yucky. I rather avoid certain classes of meals than of ingredients. I find myself new stuff to eat by rummaging the internet for recipes, and then whatever those recipes demand, I add in my shopping basket next time I go shopping for groceries. I don't need to diet, have gotten good at counting calories, and rely on that and on my own feeling of satiety to maintain my weight (as well as the trick of leaving home for hours at a time without eating out in town). I've tried cutting some stuff off my list of allowed foods (big classes of foods, such as everything sugary) and followed it successfully for months, then suddenly I started getting such strong cravings for the disallowed stuff and such a feeling of nausea when trying to continue eating my regular foods that I found it impossible and not worth it to continue.
On the other hand, this international, experimental way of cooking is absolutely completely not the way things are done around here. I always wind up with what my relatives regard as weird fancy gourmet food as opposed to the traditional food in my country. I mean, if I asked my grandma about quinoa or zucchini or persimmon or other such foreign-named stuff I eat, she'd just give me a blank stare. Besides, I do consciously avoid most processed food, push myself to eat more vegetables, and impose fairly strict limits on the caloric intakes I find acceptable, even when I'm not consciously monitoring everything I eat down to the tens of kcal. Otherwise, it's pretty much just down to cravings.
I can't say much about restaurant eating, though. It's not a habit for me. I like cooking too much, and tipping, too little.
intermittent fasting
Mind elaborating on this a bit? Do you just stop eating entirely for X days, or limit yourself to very small amounts, or what? How hard do you find it to maintain? How effective is it?
I often find abstaining from something entirely to be much easier than attempting moderation; I'm sort of wondering if this might work for me, to more reliably drop the weight I usually put on around holidays.
Use Beeminder with a weight goal, eat whatever you like when you're below the centerline, and stop eating entirely whenever you go above it, until you're under it again.
This sounds like a fairly horrible idea. There is no guarantee that you will feel like doing fasting when you go above the centerline, if anything, you go above because you are in a bad mood and eat or drink to deal with it, so you would be fasting at times when it is the least convenient. Instead, you can simply fast whenever you feel it would be easy. Whenever you feel strong and happy and proud.
I do intermittent fasting by limiting my consumption of carbs and protein to a six hour window six or seven days a week. Other people might consume only water 2 or 3 days a week. A big goal of intermittent fasting is to promote autophagy.
So what do you eat what is not carbs and not protein? Steamed broccoli? Because I have recently learned even vegs like peas or carrots have carbs. This surprised me.
How about sauerkraut? The carbs are fermented away before you eat it. Perhaps there are similar ways to cook other veggies like that.
No, for X hours. X between 12 and 24, and the first 8 hours of it asleep. Zero solid food, but a little bit of milk in my coffe is a must, I cannot drink it otherwise.
Hardness goes away after about 12 hours. But the 8 to 12 hours are bad enough to call it hard and not do it that often. Hardness depends on many factors, mood, if alcohol was drunk the day before or not etc. I cannot tell the effectiveness of it yet, as I started it when I started to do other changes as well. I am losing weight, but not sure due to this.
Sorry, as gwillen assumes below, that's my actual position proviso nobody explains to me why nutrition science is hopelessly broken and/or Campbell should be ignored. Which is what I was hoping to learn by posting this.
When talking about diet, some people are focused on health and some are focused on weight loss. These are related, but not identical. I'm assuming you're focused on health because of your phrasing.
My view is that the Mayo Clinic's food pyramid recommendations come closest to orthodox theory. The top alternative is probably Harvard's nutrition source. Neither of those two sources strike me as politically influenced. I read a lot of Aaron Carroll as I think he does a pretty balanced job of discussing a lot of nutrition research. He recently argued against the claim that heavy red meat consumption is as dangerous as people claim.
Vegetables and fruits have ridiculously good nutrient density. From that perspective Campbell is correct to focus on them. But most nutritionists would argue you should eat other foods to obtain the other nutrients. There is also some concern over claiming bigger health benefits than can be reliably demonstrated. Overall, his views come close enough to orthodoxy that I doubt it's worth worrying about too much, and his biggest difference is in the way he talks about the diet (telling people 0% instead of telling them 10%), so your views are pretty much in line with mine.
Recommendation summary:
Thus far it seems:
Limit meat consumption to >10%
Eat as much fruit as you like
Don't eat grains, replace them with root vegetables
Anything else?
No one has any gossip about overly liberal maximum residue limits? Official documentation suggests Aus and Nz food safety authorities tend to be conservative, but we're a whole another level of conservative and risk averse here :)
Based on what I know about the words "professor" and "emeritus" and "cornell", I assume this is written by an authority in the field of nutrition.
The value of being an authority in a field is that you can accurately convey the consensus within that field. Whenever consensus within a field does not exist, the ancient injunction against "argument from authority" remains true. The "authority" derives not from the authoritative individuals themselves, but the collective wisdom of the field to which they've been exposed.
- Science is crap. Don't believe expert predictions about the natural world.
Science isn't crap - it's just that when science is weird and inconsistent and wrong it's obvious and everyone notices because science has better epistemic hygiene practices than non-science methods of discovering things. You're just overestimating the degree of accuracy and agreement science aught to have.
I might have the specifics of this story wrong, but once upon a time, scientists (correctly) showed that blood cholesterol is correlated with bad things. So people stopped eating more than 1-2 eggs a day. Now we know dietary cholesterol doesn't directly control blood cholesterol and you can eat lots of eggs and your LDL won't rise in a meaningful way. That doesn't make the original findings wrong, it just means the resulting interpretation was wrong. The original scientists weren't being dumb, it was perfectly reasonable interpretation to make.
The China study found some probably correct things assuming they followed protocol and did statistics well, and now they're interpreting it to mean "go vegan". As a consumer of primary research, you should ask yourself if the findings -> practical interpretation link is reasonable.
nutrition science is crap
It's really not significantly different from "we thought there was Aether, and now we don't", but in fields like economics and psychology and nutrition people notice more when you mess up, because laymen understand enough to know what it means to make a mistake - Everybody votes, deals with minds, and eats, but most people don't understand the implications of their not being an aether. .
But, yeah - scientists are people, and some fields tend get more contaminated with personal biases that the researchers might have acquired entirely outside the laboratory. This can inform the types of questions they study, confirmation bias, bias in the interpretation of the data, and so on. Also, whenever an issue of public policy is at stake, I imagine special interests groups get involved.
Why isn't this good enough to inform your dietary choices?
The evidence certainly does inform my hypothesis, but that's not the same thing as agreeing with the author's interpretation. (I don't say "choices", because my interest is mostly academic and I'm not particularly diet conscious in my personal life, and I do factor in moral concerns with respect to meat, which makes my actual diet not particularly in line with what I think is nutritionally optimal.)
The important thing is to inform ones views based on the evidence gathered, rather than trusting the researcher to interpret their own evidence.
I accept that chinese diets are likely superior to Western diet. Leafs, shoots, roots, fruits, nuts, and the like are all extremely, extremely important. When meat replaces or otherwise funges against those foods (as you'd expect it to given limited calories per day) meat is bad. The average American lives on meat and grains, skipping the fruits and veggies, and that's no good. The average American vegetarian will probably be healthier than the average American omnivore for this reason, even controlling for caloric intake. The average American would probably benefit from going vegetarian, not to mention the various moral horrors and environmental damage meat entails. It's not surprising that we see the same trend in China.
But, well - none of that means that vegan is nutritionally optimal. Hunter gatherers, lacking grains and dairy to provide calories, would have probably "maxed out" the benefits leafs, shoots, roots, fruits, nuts, and other plants despite also eating lots of meat. The Inuit pretty much just eat meat and do fine. (Don't try it at home - the Inuit can only do this through judicious consumption of organ meats, which are glycogen rich and nutrient dense. They actually often discard the lean muscle meat, probably because they've intuitively grasped the macro-nutrient ratio problem it would pose.)
When you look at the evidence provided from the China study - not the interpretations, just the evidence - there's very little room for suggesting that hunter-gatherer diets are suboptimal.
Assuming you don't plan to become an expert in the field of nutrition yourself, what's a better way to inform your dietary choices?
There's no way out. I can say "Eat a balanced diet, with natural real foods" or whatever but the true meaning of "balanced" and "natural" is a lot more controversial than it seems at first. If you don't do your research you are down to guesswork, and after you do your research you are still mostly down to guesswork due to how little we really know.
FWIW, having a totally optimal diet is probably not extremely important in the grand scheme of things. For all practical purposes you'll be just fine so long as (1) your calories are okay, (2) your macronutrient ratios are not horribly awful, (3) you have no obvious symptoms of micronutrient deficiency, and (4) you exercise. Everyone agrees on those four and that you should eat fruits and veggies. Beyond that, it's all controversial and I doubt the additional worrying will really buy you that many extra years of quality health when one factors in the likelihood of choosing the correct arguments among the controversy. (Outside view. Inside view, I totally think I'm right in choosing the "take cues from hunter gatherers" thing.)
Based on what I know about the words "professor" and "emeritus" and "cornell", I assume this is written by an authority in the field of nutrition.
The value of being an authority in a field is that you can accurately convey the consensus within that field. Whenever consensus within a field does not exist, the ancient injunction against "argument from authority" remains true. The "authority" derives not from the authoritative individuals themselves, but the collective wisdom of the field to which they've been exposed.
Who says there is no consensus? Given that he's a nutrition science authority, and that other nutrition science authorities aren't refuting him, that's some small evidence that he's representing a consensus (there are other possible explanations as well, that I touched on in my OP).
The China study found some probably correct things assuming they followed protocol and did statistics well
I don't think they did statistics well:
Notice Campbell cites a chain of three variables: Cancer associates with cholesterol, cholesterol associates with animal protein, and therefore we infer that animal protein associates with cancer. Or from another angle: Cancer associates with cholesterol, cholesterol negatively associates with plant protein, and therefore we infer plant protein protects against cancer.
But when we actually track down the direct correlation between animal protein and cancer, there is no statistically significant positive trend. None. Looking directly at animal protein intake, we have the following correlations with cancers:
I've seen her critique, but with her being a blogger and me being neither a statistician, epidemiologist, nor a nutritionist, and after seeing the resulting fight about methodology in the comments by people who claim to be those things, and knowing that Campbell stands by his claims even after reading her critique and has written his response, and with me having a rather low base rate confidence in any given study being correct anyway, it didn't influence my opinion that much in any direction.
I'm pretty much out of my depth insofar as methodology is concerned in this case so, I'm not really in a position to evaluate anything on those grounds, yet. It at least feels more productive to just skim tons of abstracts and get a big picture idea than to analyze whether one particular study is correct.
Also, there's a big difference between the claims of The China Study book which cites a range of findings (some of which I believe fall into the "made sense at the time but are now outdated" category), and the findings of the China-Oxford-Cornell study in particular, and as I read her critique it seems she's getting those two confounded.
PS - The "meat, especially red meat, is carcinogenic" claim is one of those for which Cambell provided fairly robust support from other studies, not relying on the China-Oxford-Cornell data alone. I think subsequent research found that preserved meat (deli, smoked, etc) and maybe various common methods of grilling explain the carcinogenic factor, but don't quote or trust me. (Not that I have strong priors against meat being carcinogenic, the "ancestral environment" arguments might not hold for extremely late-stage diseases like cancer)
me having a rather low base rate confidence in any given study being correct anyway, it didn't influence my opinion that much in any direction.
If your prior is that the study likely doesn't provide much value then this might not change your opinion. On the other hand reaffirm your priors should mean not putting much weight in Campbell case.
On the other hand reaffirm your priors should mean not putting much weight in Campbell case.
Not sure I understand what is meant by this.
Was trying to say: The data brings value. I don't trust conclusions drawn from data. I also don't trust Minger's belief that the data analysis was obviously flawed because I see many people arguing over that. Rather than investigating further about Minger vs. Cambell on an argument that has experts disagreeing, it's more worthwhile as a reader to just provisionally assume the data analysis is passable and read more on the topic elsewhere, because the risk of being mislead by flawed data analysis or other methodological issues is ever present, and in a field like this one is better off reading widely and look for broad trends and conceptual replications than one is by reading extremely closely. (And hoping any wrong beliefs brought about by bad data analysis fall away because the other experiments don't support them.)
That's what I mean by "low base rate". If I'm just reading to get a big picture of reality in a field, rather than dive into the difficult rabbit hole of "are the methods ok", I just operate under the assumption that there's always an x% risk of any given study being flat-out wrong about everything and keep reading more without worrying about it.
(Which is why "Minger disagrees with those methods" falls into the "well, methods are frequently complicated and controversial and you've already factored that in so don't worry" box. If other experts unanimously chimed in agreement with Minger, or if what she wrote about the flaws seemed obviously true to me, it would be a different matter).
I've come across this quite often. This is written by an amateur whose authority stems from "I typically spend about five hours a day reading and writing about nutrition—voluntarily".
As a layperson myself I'd be a lot more moved if other nutrition scientists agreed with her. As it stands for me her input is basically +1 "non-nutrition scientists disagree' with Campbell".
There's a book called The China Study. It's written by the "Professor Emeritus of Nutritional Biochemistry at Cornell University, and his son Thomas M. Campbell II, a physician". Based on what I know about the words "professor" and "emeritus" and "cornell", I assume this is written by an authority in the field of nutrition.
When it was published in 2005 it recommended clearly crazy stuff: by minimizing or eliminating the consumption of animal based foods as well as refined/processed foods (e.g. adopt a "whole food plant-based diet"), you could greatly reduce your risk of diseases of affluence like heart disease, diabetes, some cancers, etc. The book follows his 60+ year career through cancer experiments on animals, conducting a pretty large epidemiological study (the China-Cornell-Oxford study), and then discusses some important clinical trials that support his recommendations. He also surveys some nutrition literature that corroborates his research.
Some other experts vocally support him; further, his recommendations don't seem to be a radical departure from either public health recommendations or prior research in the field. The FDA MyPlate, and also the UK's health initiatives ("5 fruits/vegetables a day"), as well as the Harvard School of Public Health's recommendations and others all seem to be moving in his general direction, although seemingly filtered by politics (e.g. telling Americans to stop eating meat entirely seems like political suicide, so baby steps in the direction seem more expedient; but I'm conjecturing this).
The book is widely dismissed as vegan propaganda, but the author says he's not advocating a vegan diet and in fact criticizes vegan diets as only minimally healthier than the "standard American diet". He also conducted experiments which subjected animals to carcinogens, which is not a very vegan thing to do. He does not admit to being vegan. He even observes that the evidence says restricting animal based calories to under 10% of total calories offers almost all of the health benefits as restricting them to 0%, but says as a practical matter this is much harder to stick to (e.g. you may only eat a 3mm slice of chocolate cake is much harder than simply saying no to chocolate cake). He also admits he had a bias when he entered the field of nutrition, but a bias in favor of attempting to justify the use of dairy to cure malnutrition (he came from a family of dairy farmers). He said when he discovered that his research did not support his dairy bias he abandoned his dairy bias (and would later shut down his diary farm).
Anyway, the China Study is widely criticized, but not by people in his field? I've been watching for several years now (I adopted the diet myself in 2010), and all of the negative critiques tend to fall into (a) critiques from non-experts, (b) critiques from experts in unrelated fields, (c) health experts who agree that his recommendations have merit, but that they're impractical for the general public to follow.
(C is worthwhile, but this is a problem for public health authorities to worry about. I'm much more interested in what any sufficiently motivated individual can elect to do to maximize their health)
So, this is the part that I find most surprising. There are lots of people who are PhDs of exercise, anthropology, or economics who criticize his recommendations, but I have a hard time finding a mass gathering of nutrition scientists coming out of the woodwork to shoot down his recommendations.
What should I believe? Here are things I've considered.
1. Science is crap. Don't believe expert predictions about the natural world.
2. No no, just nutrition science is crap. Don't believe any expert predictions about nutrition.
3. Nutrition science isn't crap, but the Campbells are rogue and the community of nutrition scientists have better things to do than debunk pop culture books.
4. Nutrition scientists **are** criticizing him in droves, I just don't come across them because I have confirmation bias blinders on.
5. "Nutrition scientist" is a made up discipline, and I've been tricked!
I'm more or less at a loss on how to make progress on these points. Am I missing something crucial?
What's the LW take on this? Why isn't this good enough to inform your dietary choices? Assuming you don't plan to become an expert in the field of nutrition yourself, what's a better way to inform your dietary choices?
EDIT: I would just like to thank everyone who responded. I've tried to discuss this in many forums, both IRL and on the internet and it's almost always a disaster unlike here on LW. Your measured, insightful responses are an enormous relief. You've given me a lot of food (ha!) for thought.