I would like to endorse that last item, that there is a potential harm that is not widely known. It's not specific to veganism, but the risk is elevated for them.
Oxalic acid is ubiquitous in plant-based foods. Absorbed oxalic acid can precipitate in the body as calcium oxalate. This most often damages the kidneys, but it can also cause joint pains and degeneration. The crystals are not as inflammatory as the crystals that cause gout, but they are much more persistent.
People who have trouble with fat absorption are at an increased risk for getting too much oxalic acid from their diet, a condition called enteric hyperoxaluria / oxalosis. These include persons treated for obesity with baryatric surgery or old fashioned weight loss drugs, and sufferers of IBD. This is a growing demographic. Their problems with kidneys and joints can very easily be imputed to pre-existing conditions like diabetes, overweight or autoimmune disorders.
The studies on oxalate content of foods are somewhat conflicting as to the precise amounts in each plant or foodstuff. It is not always clear what part is bound to e.g. calcium and how much is in a more readily absorbed form.
Legumes seem to contain significant amounts. Rhubarb is a well known source, but how many people know that a larger serving of carrots, sweet potatoes or almonds can be just as dangerous? Processing methods have a big effect: instant coffee has manyfold higher levels than ground and percolated coffee.
Oxalic acid also has some endogenous sources in the body, such as protein metabolism. It is a metabolite of both xylitol and ascorbic acid. Gut flora can both generate and consume oxalic acid, depending on the species.
I haven't found any oxalate data on novel highly processed plant based foods like meat and dairy substitutes. Fermentation might push it either way. Many of the ingredients, like mushrooms, almonds, spinach, beetroot and coconut seem to have very high levels of oxalate to begin with.
Perhaps you can now see why I'm worried. Add some supplement (or eating liver as suggested in other comments) that has too much vitamin A or D to the mix and you might also get a high blood calcium level and more crystallization in the body.
Oxalic acid is more famously the most common constituent of stones in the urinary tract. Kidney stones are often described as a "ten" on the pain scale from 1 to 10. It is not given that large stones will be the first symptom of too much oxalic acid, their formation might require low hydration or abnormalities in the pH of the urine. Smaller stones or crystals might imitate a urinary tract infection or a STD with painful discharge. There might be no urinary symptoms other than those resulting from kidney damage. Animal protein intake is a risk factor for renal and urinary tract calculi, so if vegans don't have a higher risk of stones it does not necessarily mean they are safe from other oxalate pathologies. But stones are definitely something to look for.
The standard way to prevent problems with dietary oxalic acid is to consume a small amount of calcium carbonate after meals to bind it in a non-soluble form. I would also recommend that people avoid xylitol and big doses of vitamins A, C and D.
If you are now concerned about it (you're welcome!), oxalate absorption and production can be assessed with a 24-hour urine collection sample. Note that the upper reference range might not be all that far from what is observed in primary (i.e. hereditary) hyperoxaluria, a very serious condition.
Most likely oxalic acid does not and will not have a big impact on the health of the vegan population. But is has some potential of being a major under-the-radar (persistent and low-grade inflammatory, crystal deposits perhaps hard to image) threat for serious and long-term problems like chronic kidney disease and osteoarthritis. Why do some people get these conditions early in life?
I hope this helps.
PS. I'm not a vegan, but I believe meat and dairy has had an immense negative impact on everyone's health, including vegans. There is of course the historic zoonotic origin of many high impact infectious diseases in domesticated animals. But I'm talking about a more modern development.
It used to be the case that the distribution and prevalence of gut microbiota was largely dependent on the fitness and mobility of the host. Nowadays the vast majority of mammal biomass is either livestock or humans. Their mobility and that of their manure is mainly supported by technology.
This independence of the host's fitness frees the microbiome to increase its own fitness in new, potentially pathogenic ways. One obvious modification could be to make the host eat more. Because the manure is spread by mechanized means, any increase in eaten and excreted volume results in a roughly proportionate advantage to the microbe. Animal breeding and market forces aren't strictly working against this development, perhaps the opposite.
This model of the etiology of obesity fits with the geographical prevalence: lower at high altitudes, i.e. upstream of agriculture. It would also explain why wild animals are getting fatter, if that is the case. It suggests the quick health fix of getting a fecal transplant from a healthy hunter-gatherer. The more remote and isolated the donor, the better. But we would have to be careful not to corrupt them as they get wealthy off their product.
Introduction
To me, it is obvious that veganism introduces challenges to most people. Solving the challenges is possible for most but not all people, and often requires trade-offs that may or may not be worth it. I’ve seen effective altruist vegan advocates deny outright that trade-offs exist, or more often imply it while making technically true statements. This got to the point that a generation of EAs went vegan without health research, some of whom are already paying health costs for it, and I tentatively believe it’s harming animals as well.
Discussions about the challenges of veganism and ensuing trade-offs tend to go poorly, but I think it’s too important to ignore. I’ve created this post so I can lay out my views as legibly as possible, and invite people to present evidence I’m wrong.
One reason discussions about this tend to go so poorly is that the topic is so deeply emotionally and morally charged. Actually, it’s worse than that: it’s deeply emotionally and morally charged for one side in a conversation, and often a vague irritant to the other. Having your deepest moral convictions treated as an annoyance to others is an awful feeling, maybe worse than them having opposing but strong feelings. So I want to be clear that I respect both the belief that animals can suffer and the work advocates put into reducing that suffering. I don’t prioritize it as highly as you do, but I am glad you are doing (parts of) it.
But it’s entirely possible for it to be simultaneously true that animal suffering is morally relevant, and veganism has trade-offs for most people. You can argue that the trade-offs don’t matter, that no cost would justify the consumption of animals, and I have a section discussing that, but even that wouldn’t mean the trade-offs don’t exist.
This post covers a lot of ground, and is targeted at a fairly small audience. If you already agree with me I expect you can skip most of this, maybe check out the comments if you want the counter-evidence. I have a section addressing potential counter-arguments, and probably most people don’t need to read my response to arguments they didn’t plan on making. Because I expect modular reading, some pieces of information show up in more than one section. Anyone reading the piece end to end has my apologies for that.
However, I expect the best arguments to come from people who have read the entire thing, and at a minimum the “my cruxes” and “evidence I’m looking for” sections. I also ask you to check the preemptive response section for your argument, and engage with my response if it relates to your point. I realize that’s a long read, but I’ve spent hundreds of hours on this, including providing nutritional services to veg*ns directly, so I feel like this is a reasonable request.
My cruxes
Below are all of the cruxes I could identify for my conclusion that veganism has trade-offs, and they include health:
Those are my premises. Below are a few conclusions I draw from them. I originally didn’t plan on including a conclusion, but an early reader suggested my conclusions were milder than they expected and it might be good to share them. So:
My evidence
One is first principles. Animal products are incredibly nutrient dense. You can get a bit of all known nutrients from plants and fortified products, and you can find a vegan food that’s at least pretty good for every nutrient, but getting enough of all of them is a serious logic puzzle unless you have good genes. Short of medical issues it can be done, but for most people it will take some combination of more money, more planning, more work, and less joy from food.
“Short of medical issues” is burying the lede. Food allergies and digestion issues mean lots of people struggle to feed themselves even with animal products; giving up a valuable chunk of their remaining options comes at a huge cost.
[Of course some people have issues such that animal products are bad for them and giving them up is an improvement. Those raise veganism’s average health score but don’t cancel out the people who would suffer]
More empirically, there is this study from Faunalytics, which found 29% of ex-vegans and ex-vegetarians in their sample had nutritional issues, and 80% got better within three months of quitting. Their recorded attrition rate was 84%, so if you assume no current veg*ns have issues that implies a 24% of all current and former veg*ns develop health issues from the diet (19% if you only include issues meat products cured quickly). I’m really sad to only be giving you this one study, but most of the literature is terrible (see below).
The Faunalytics study has a fair number of limitations, which I went into more detail on here. My guess is that their number is a moderate underestimate of the real rate, and a severe underestimate of the value for naive vegans in particular, but 24% is high enough that I don’t think the difference matters so I’ll use that for the rest of the post.
Evidence I’m looking for
The ideal study is a longitudinal RCT where diet is randomly assigned, cost (across all dimensions, not just money) is held constant, and participants are studied over multiple years to track cumulative effects. I assume that doesn’t exist, but the closer we can get the better.
I’ve spent several hours looking for good studies on vegan nutrition, of which the only one that was even passable was the Faunalytics study. My search was by no means complete, but enough to spot some persistent flaws among multiple studies. I’ve also spent a fair amount of time checking citations made in support of vegan claims, only to find the study is either atrocious or doesn’t support the claim made (examples in the “This is a strawman…” section). There is also some history of goalpost moving, where an advocate cites a study, I criticize it, and they say it doesn’t matter and cite a new study. This is exhausting.
I ask that you only cite evidence you, personally, find compelling and are willing to stand by, and note its flaws in your initial citation. That doesn’t mean the study has to be perfect, that’s impossible, but you should know the flaws and be ready to explain why you still believe the study. If your belief rests on many studies instead of just one (a perfectly reasonable, nee admirable, state), please cite all of them. I am going to be pretty hard on people who link to seriously flawed studies without disclosing the flaws, or who retract citations without updating their own beliefs.
A non-exhaustive list of common flaws:
A non-exhaustive list of evidence I hope for:
Preemptive responses to counter-arguments
There are a few counter-arguments I’ve already gotten or expect to get shortly, so let me address them ahead of time.
“You’re singling out veganism”
Multiple people have suggested it’s wrong for me to focus on veganism. If I build enough trust and rapport with them they will often admit that veganism obviously involves some trade-offs, if only because any dietary change has trade-offs, but they think I’m unfairly singling veganism out.
First off, I’ve been writing about nutrition under this name since 2014. Earlier, if you count the pseudonymous livejournal. I talk about non-vegan nutrition all the time. I wrote a short unrelated nutrition post while this one was in editing. I understand the mistake if you’re unfamiliar with my work, but I assure you this is not a hobby I picked up to annoy you.
It’s true that I am paying more attention to veganism than I am to, say, the trad carnivore idiots, even though I think that diet is worse. But veganism is where the people are, both near me and in the US as a whole. Dietary change is so synonymous with animal protection within Effective Altruism that the EAForum tag is a wholly-owned subsidiary of the animal suffering tag. At a young-EA-organizer conference I mentored at last year, something like half of attendees were vegan, and only a handful had no animal-protecting diet considerations. If keto gets anywhere near this kind of numbers I assure you I will say something.
“The costs of misinformation are small relative to the benefits of animals”
One possible argument for downplaying or dismissing the costs of veganism is that factory farming is so bad anything is justified in stopping it. I’m open to that argument in the abstract, but empirically I think this isn’t working and animals would be better off if people were given proper information.
First, it’s not clear to me the costs of acknowledging vegan nutrition issues are that high. I’ve gotten a few dozen comments/emails/etc on my vegan nutrition project of the form “This inspired me to get tested, here are my supplements, here are my results”. No one has told me they’ve restarted consuming meat or even milk. It is possible people are less likely to volunteer diet changes, although I do note I’m not vegan.
But even if education causes many people to bounce off, the alternative may be worse.
That Faunalytics study says 24% of people leave veg*nism due to health reasons. If you use really naive math, that suggests that ignoring nutrition issues would need to increase recruitment by 33%, just to break even. But people who quit veganism due to health issues tend to do so with a vitriol not seen in people leaving for other reasons. I don’t have numbers for this, but r/exvegans is mostly people who left for health reasons (with a smattering of people compelled by parents), as are the ex-vegans angry enough to start blogs. Even if they don’t make a lifestyle out of it, people who feel harmed are less likely to retry veganism, and more likely to discourage their friends.
I made a toy model comparing the trade off of education (which may lead people to bounce off) vs. lack of education (which leads people to quit and discourage others). The result is very sensitive to assumptions, especially “how many counterfactual vegans do angry ex-vegans prevent?”. If you put the attrition rate as low as I do, education is clearly the best decision from an animal suffering perspective. If you put it higher it becomes very sensitive to other assumptions. It is fairly hard to make a slam-dunk case against nutritional awareness, but then, (points at years of nutrition blogging) I would say that.
“The human health gains are small relative to the harms to animals”
I think this is a fair argument to make, and the answer comes down to complicated math. To their credit, vegan EAs have done an enormous amount of math on the exact numeric suffering of farmed animals. But honest accounting requires looking at the costs as well.
“The health costs don’t matter, no benefit justifies the horror of farming animals”
This is a fair argument for veganism. But it’s not grounds to declare the health costs to be zero.
It’s also not grounds to ignore nutrition within a plant-based diet. Even if veganism is healthy for everyone and no harder a switch than other diets, it is very normal for dietary changes to entail trade-offs and have some upfront costs. The push to deny trade-offs and punish those who investigate them (see below) is hurting your own people.
“This is a strawman, vegans already address nutrition”
I fully acknowledge that there are a lot of resources on vegan nutrition, and that a lot of the outreach literature at least name-checks dietary planning. But I talk to a lot of people (primarily young EAs focused on non-animal projects) with stories like this one, of people going vegan as a group without remembering a single mention of B12 or iron. I would consider that a serious problem even if I couldn’t point to anything the movement was doing to cause it.
But I absolutely can point to things within the movement that create the problem. There are some outright lies, and a lot more well-crafted sentences that are technically correct but in aggregate leave people with deeply misleading impressions.
While reading, please keep in mind that these are formal statements by respected vegans and animal protection organizations (to the best of my ability to determine). All movements have idiots saying horrible things on reddit, and it’s not fair to judge the whole movement by them. But please keep that context in mind while reading: these were not off-the-cuff statements or quick tweets, but things a movement leader thought about and wrote down.
The piece ends with “When people tell me they want to feed [their pet] a vegan diet, I say, ‘Get a goat, get a rabbit”.
While this can be useful, as in the case of a planned non-vegan diet, it is not necessary. A vegan diet is suitable for people of all ages and conditions. A vegan nutritionist may help plan custom menus to meet specific requirements – for instance, if you are an athlete or if you want to gain or lose a lot of weight as a vegan. It is always advised to consult a nutritionist regularly for a check-up. However, it is important to note that some nutritionists are biased and don’t know a lot about vegan nutrition. Note also that medical doctors are often not experts on nutrition.”
Why is this so hard to talk about?
This is probably the least important section. I’m including it mostly in the hope it lowers friction in the object-level conversation.
The stakes are so high
Hardcore vegan advocates believe we are surrounded by mass torture and slaughter facilities killing thousands of beings every day. That’s the kind of crisis that makes it hard to do really nuanced math people may use to justify ignoring you.
Vegans are sick of concern trolls
Vegans frequently have to deal with bad-faith interrogation of their choices (“wHxt ABuoT proTEIn?!?!”). I imagine this is infuriating, and I’ve worked really hard to set myself apart by things like investing hundreds of hours of my time, much of which was unpaid, and working to get vegans the nutrition they needed to stay healthy and vegan.
Typical minding/failure of imagination
People who find veganism easier are disproportionately likely to become and stay vegan. That’s what the word “easy” means. Then some of them assume their experiences are more representative than they are, and that people who report more difficulty are lying.
E.g. this comment on an earlier post (not even by a vegan- he was a vegan’s partner) said “there is nothing special one needs to do to stay healthy [while eating vegan]” because “most processed products like oat milk, soy milk, impossible meat, beyond meat, daiya cheese are enriched with whatever supplements are needed”. Which I would describe as “all you need to do to stay healthy while vegan is eat fortified products”. That’s indeed pretty easy, and some people will do it without thinking. But it’s not nothing, especially when “no processed foods” is such a common restriction. Sure enough, Faunalytics found that veg*ns who quit were less likely (relative to current veg*ns) to eat fortified foods.
That same person later left another comment, conceding this point and also that there were people the fortified foods didn’t work for. Which is great, but it belonged in the first comment.
Or this commenter, who couldn’t imagine a naive vegan until an ex-vegan described the total ignorance they and their entire college EA group operated under.
Lies we tell omnivores
Ozy Brennan has a post “Lies to cis people”. They posit that trans advocates, faced with a hostile public, give a story of gender that is simplified (because most people won’t hear the nuance anyway), and prioritizes being treated well over conveying the most possible truth. The intention is that an actual trans person or deeply invested ally will go deeper into the culture and get a more nuanced view. This can lead to some conflict when a person tries to explore gender with only the official literature as their guide.
Similarly, “veganism requires no sacrifice on any front, for anyone” is a lie vegans tell current omnivores. I suspect the expectation, perhaps subconscious, is that once they convert to veganism they’ll hang around other vegans and pick up some recipes, know what tests to get, and hear recommendations for vegan vitamins without doing anything deliberately. The longer sentence would be “for most people veganism requires no sacrifice beyond occasional tests and vitamins, which is really not much work at all”.
But this screws over new vegans who don’t end up in those subcultures. It’s especially bad if they’re surrounded by enough other vegans that it feels like they should get the knowledge, but the transmission was somehow cut off. I think this has happened with x-risk focused EA vegans, and two friends described a similar phenomenon in the straight-edge punk scene.
Failure to hear distinctions, on both sides
I imagine many people do overestimate the sacrifice involved in becoming vegan. The tradeoff is often less than they think, especially once they get over the initial hump. If omnivores are literally unable to hear “well yes, but for most people only a bit”, it’s very tempting to tell them “not at all”. But this can lead even the average person to do less work than they should, and leaves vegans unable to recognize people for whom plant based diets are genuinely very difficult, if not impossible.
Conclusion
I think veganism comes with trade-offs, health is one of the axes, and that the health issues are often but not always solvable. This is orthogonal to the moral issue of animal suffering. If I’m right, animal EAs need to change their messaging around vegan diets, and start self-policing misinformation. If I’m wrong, I need to write some retractions and/or shut the hell up.
Discussions like this are really hard, and have gone poorly in the past. But I’m still hopeful, because animal EAs have exemplified some of the best parts of effective altruism, like taking weird ideas seriously, moral math, and checking to see if a program actually worked. I want that same epistemic rigor applied to nutrition, and I’m hopeful about what will happen if it is.
Thanks to Patrick La Victoire and Raymond Arnold for long discussions and beta-reading, and Sam Cottrell for research assistance.