(a good number of people feel just as fine on a vegan diet as a non-vegan one [example] - most of the potential “costs” are in terms of energy/vitality which they will feel if they feel it). I am ovo-vegetarian and I have reasonably high iron levels myself. From the limited studies available, vegans have lower ACM than even vegetarians do.
It’s important for people to get an ION Panel to test for amino acid deficiencies (these are hard to order w/o a doctor)
Scientists found three genes linked with vegetarianism and another 31 genes that are potentially associated.
Several of these genes, according to the study, are involved in lipid (fat) metabolism and/or brain function including two of the top three (NPC1 and RMC1).
“My speculation is there may be lipid component(s) present in meat that some people need. And maybe people whose genetics favor vegetarianism are able to synthesize these components endogenously,” Dr Yaseen said.
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4.2. Long Term Health Outcomes
Estimating the long-term health outcomes of eating certain things is difficult because food is highly bound up in the culture we live in and culture correlates to just about every health outcome you could possibly imagine. Even less conveniently, nutritional science is highly anti-inductive; if a particular food group is identified as being healthy people with an interest in being healthy flock to that food group, and people with an interest in being healthy are likely to be healthy for a bunch of reasons regardless of diet.
So here’s a nice headline result: vegetarians have less heart disease with extremely high certainty, and probably less cardiovascular disease and cancer too. Most of the studies in that meta-analysis have had some of the really obvious stuff adjusted away (race, income, etc.) but not all studies adjust for all confounders, and we should be cautious about trusting studies that ‘adjust for confounders’. If you ignore confounders then the answer is clear; eating vegetarian is good for you in every single way we can measure (including, possibly, circulating testosterone in defiance of stereotypes about meat eaters!).
If you are interested in confounders: There are a handful of cool natural experiments, taking groups with reasons to eat certain food but not bother with the associated healthy lifestyles, which are the closest we are likely to come to a true experiment in this area. In particular, the American Adventist Health Studies are pretty much state of the art in the field from what we can see. Adventists have quite unique dietary habits, brought about by religious prohibitions on certain foodstuffs which some Adventist churches follow and some don’t. Consequently, if you are an Adventist you are functionally ‘randomized’ into different food-eating conditions depending on which church you attend, and this randomization can be exploited by researchers.
Based on the Adventist Health Studies, a vegetarian diet increases life expectancy by around 3.6 years. The less meat you eat, the healthier your BMI and the less likely you are to get diabetes.
Overall we might expect lacto-ovo vegetarians to have a health related quality of life around 10% better than a meat eater, with most of this benefit being apparent 20 years after making the switch to a vegetarian diet.
You could complicate this picture a lot (especially by introducing future discounting) but we think the general principle that if you value life-years towards the end of your life you should likely go vegetarian is well demonstrated by the data:
One final point on how meat might affect your lifespan; there is a growing awareness of the fact that industrially produced meat is an ideal breeding ground for zoonotic disease, and that those diseases can mutate and jump to humans very quickly. Previous pandemics such as H1N1 (‘swine flu’) and H5N1 (‘bird flu’) may have originated with farmed animals, and were rapidly spread by the close contact of unhealthy animals and global nature of the meat supply chain. At the margin, eating meat probably increases the probability of a global pandemic but there isn’t good evidence on how much your individual consumption affects things at the margin.
In the model we take the Adventist study result at almost face value, estimating that eating vegetarian will increase your lifespan by 3 years, and include constant low costs due to possible nutritional deficiency and moderate benefits to health that appear later in life.
Thank you for the link, that adventist data is indeed beautiful. But if I’m reading it correctly it’s comparing omnivores to vegetarians, not vegans. I think eggs and milk handle most of the issues caused by veganism, so this doesn’t update me on that front.
Hi Elizabeth, I’m the co-author of the piece linked above. You’re absolutely right we chose to focus on the omnivore-vs-vegetarian comparison, for a variety of different reasons. However, AHS-2 does have some comparisons between omnivores to vegans. From the abstract: “the adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs non-vegetarians was 0.88 (95% CI, 0.80–0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73–1.01)”. So depending on how strict you are being with statistical significance there’s somewhere between a small signal and no signal that veganism is better with respect to all-cause mortality than omnivorism.
I think AHS is the best data we’ve got on this topic, but I’d be cautious about over-interpreting it. In my mind the biggest criticism is that Adventists are generally more healthy than the typical American (they do a lot more exercise, avoid alcohol and tobacco etc), which leads to extremely pernicious selection bias. For example, it could be that a vegan diet is much healthier than an omnivorous diet if you are the kind of person who spends a lot of time worrying about your health generally, but the risk of getting the wrong nutrients is so high with a vegan diet that it is harmful to people who are not otherwise concerned about their health. So I’m not confident the very slight improvement in overall mortality from switching from a vegetarian diet to a vegan diet can be judged to be a real effect from AHS alone.
On the other hand, I think I would be confident enough in the AHS data to say that it shows that veg*nism does not entail a tradeoff on the ‘years of life lived’ axis. The most conservative reading of the data possible would be that a veg*n diet has no effect on years of life lived, and I think it is probably more reasonable to read the AHS study as likely underestimating the benefits a veg*n diet would give the average person. Obviously ‘years of life lived’ is not the same thing as ‘health’ so I’m not saying this is a knock-down argument against your main point—just wanted to contextualise how we were using the data in the linked piece.
Scott describes the study as functionally randomized because restrictions vary by church, which is indeed the closest I could possibly hope to get with a nutrition RCT. However the cohort description makes no mention of this, and the 7DA I talked to said that it wasn’t his experience: individual churches varied a little in their recommendations, but people within the same church varied a little in their choice of diet. This seems corroborated by the fact that meat eating is associated with ~every bad thing.
Also if I’m reading this correctly, the rank ordering of death rates is for women: pescatarian < lacto-ovo-veg <vegan < omnivore (lower is better) for men: pescatarian =~ vegan < lacto-ovo vegetarian < omnivore
I have several questions on how you did the statistics, would you be willing to talk more over email?
Ah sorry, I seem to have slightly misled you. The quote which you attribute to Scott is actually written by me and the co-author of an adversarial collaboration hosted on Scott’s old blog. I’m not the author of the Adventist Health Study linked, much that I wish I was!
If you have questions about the statistics in the adversarial collaboration I’d be more than happy to talk through the approach we used. If you have questions about AHS2, by all means let’s share the work of finding the answer but I can’t promise to be any more help than any other random person you’d pick off the street
Getting the paper author on EAF did seem like an unreasonable stroke of good luck.
I wrote out my full thoughts here, before I saw your response, but the above captures a lot of it. The data in the paper is very different than what you described. I think it was especially misleading to give all the caveats you did without mentioning that pescetarianism tied with veganism in men, and surpassed it for women.
I made the mistake of looking at the total of the 7DA health data and I’m both excited and overwhelmed. Are there papers you would recommend I prioritize, besides the AHS2 one? Is there anything on adventists with medical issues affecting digestion?
most of the potential “costs” are in terms of energy/vitality which they will feel if they feel it
I think there are many people for whom this is not true.* Many of even the most-affected people don’t keel over the second they decide to identify as vegan; it takes time for nutrient stores to deplete. If it happens slowly enough they may never notice, or not notice until it becomes life-ruiningly severe (obviously this effect isn’t unique to veganism, and many of the ill effects of meat are very hard to notice). I’ve also seen vegans who knew they had serious energy issues just… not consider diet as a hypothesis, and not had any vegan friends suggest it either.
I want to be fair, so I should note that in one case I’m thinking of there’s some evidence veganism wasn’t the problem. It’s the person here who tested deficient on almost everything including vitamin C, which is just not a problem a plant-based diet should cause. But something has gone wrong if anyone with fatigue issues doesn’t consider dietary causes, much less a vegan.
*I feel like I should quantify many here but it’s hard because by definition, everyone I see with a fatigue issue either hasn’t noticed or doesn’t know how to fix it. People who notice minor energy drops and immediately fix them drop out from the sample.
https://slatestarcodex.com/2019/12/11/acc-is-eating-meat-a-net-harm/?utm_source=substack&utm_medium=email
(a good number of people feel just as fine on a vegan diet as a non-vegan one [example] - most of the potential “costs” are in terms of energy/vitality which they will feel if they feel it). I am ovo-vegetarian and I have reasonably high iron levels myself. From the limited studies available, vegans have lower ACM than even vegetarians do.
It’s important for people to get an ION Panel to test for amino acid deficiencies (these are hard to order w/o a doctor)
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Thank you for the link, that adventist data is indeed beautiful. But if I’m reading it correctly it’s comparing omnivores to vegetarians, not vegans. I think eggs and milk handle most of the issues caused by veganism, so this doesn’t update me on that front.
Hi Elizabeth, I’m the co-author of the piece linked above. You’re absolutely right we chose to focus on the omnivore-vs-vegetarian comparison, for a variety of different reasons. However, AHS-2 does have some comparisons between omnivores to vegans. From the abstract: “the adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs non-vegetarians was 0.88 (95% CI, 0.80–0.97). The adjusted HR for all-cause mortality in vegans was 0.85 (95% CI, 0.73–1.01)”. So depending on how strict you are being with statistical significance there’s somewhere between a small signal and no signal that veganism is better with respect to all-cause mortality than omnivorism.
I think AHS is the best data we’ve got on this topic, but I’d be cautious about over-interpreting it. In my mind the biggest criticism is that Adventists are generally more healthy than the typical American (they do a lot more exercise, avoid alcohol and tobacco etc), which leads to extremely pernicious selection bias. For example, it could be that a vegan diet is much healthier than an omnivorous diet if you are the kind of person who spends a lot of time worrying about your health generally, but the risk of getting the wrong nutrients is so high with a vegan diet that it is harmful to people who are not otherwise concerned about their health. So I’m not confident the very slight improvement in overall mortality from switching from a vegetarian diet to a vegan diet can be judged to be a real effect from AHS alone.
On the other hand, I think I would be confident enough in the AHS data to say that it shows that veg*nism does not entail a tradeoff on the ‘years of life lived’ axis. The most conservative reading of the data possible would be that a veg*n diet has no effect on years of life lived, and I think it is probably more reasonable to read the AHS study as likely underestimating the benefits a veg*n diet would give the average person. Obviously ‘years of life lived’ is not the same thing as ‘health’ so I’m not saying this is a knock-down argument against your main point—just wanted to contextualise how we were using the data in the linked piece.
Scott describes the study as functionally randomized because restrictions vary by church, which is indeed the closest I could possibly hope to get with a nutrition RCT. However the cohort description makes no mention of this, and the 7DA I talked to said that it wasn’t his experience: individual churches varied a little in their recommendations, but people within the same church varied a little in their choice of diet. This seems corroborated by the fact that meat eating is associated with ~every bad thing.
Also if I’m reading this correctly, the rank ordering of death rates is
for women: pescatarian < lacto-ovo-veg <vegan < omnivore (lower is better)
for men: pescatarian =~ vegan < lacto-ovo vegetarian < omnivore
I have several questions on how you did the statistics, would you be willing to talk more over email?
Ah sorry, I seem to have slightly misled you. The quote which you attribute to Scott is actually written by me and the co-author of an adversarial collaboration hosted on Scott’s old blog. I’m not the author of the Adventist Health Study linked, much that I wish I was!
If you have questions about the statistics in the adversarial collaboration I’d be more than happy to talk through the approach we used. If you have questions about AHS2, by all means let’s share the work of finding the answer but I can’t promise to be any more help than any other random person you’d pick off the street
Getting the paper author on EAF did seem like an unreasonable stroke of good luck.
I wrote out my full thoughts here, before I saw your response, but the above captures a lot of it. The data in the paper is very different than what you described. I think it was especially misleading to give all the caveats you did without mentioning that pescetarianism tied with veganism in men, and surpassed it for women.
I made the mistake of looking at the total of the 7DA health data and I’m both excited and overwhelmed. Are there papers you would recommend I prioritize, besides the AHS2 one? Is there anything on adventists with medical issues affecting digestion?
I think there are many people for whom this is not true.* Many of even the most-affected people don’t keel over the second they decide to identify as vegan; it takes time for nutrient stores to deplete. If it happens slowly enough they may never notice, or not notice until it becomes life-ruiningly severe (obviously this effect isn’t unique to veganism, and many of the ill effects of meat are very hard to notice). I’ve also seen vegans who knew they had serious energy issues just… not consider diet as a hypothesis, and not had any vegan friends suggest it either.
I want to be fair, so I should note that in one case I’m thinking of there’s some evidence veganism wasn’t the problem. It’s the person here who tested deficient on almost everything including vitamin C, which is just not a problem a plant-based diet should cause. But something has gone wrong if anyone with fatigue issues doesn’t consider dietary causes, much less a vegan.
*I feel like I should quantify many here but it’s hard because by definition, everyone I see with a fatigue issue either hasn’t noticed or doesn’t know how to fix it. People who notice minor energy drops and immediately fix them drop out from the sample.