I don’t doubt the Faunalytics data. If anything the number seems surprisingly low, considering it comes from self-reporting among people who went on to quit veganism.
I’m not sure how to weigh ‘importance’ other than subjectively, but I’ll attempt to at least put bounds on it. As a floor, some number of people experience health issues that are important enough to them that they are motivated to quit veganism. As a ceiling, the health risks of veganism are less important than those of other harms related to diet – for example, dyslipidaemia or diabetes – that increase mortality, given that veganism doesn’t seem to increase mortality and may reduce it.
My stance at the moment is still more ‘generally confused about what you’re trying to communicate/achieve’ than ‘disagreeing with a particular claim you’re making’. I’d like to close the inferential distance if possible, but feel free to ignore this comment if you don’t think it’s leading anywhere useful.
I still don’t understand which of the following (if any) you would endorse:
Many vegans don’t know about the risk of nutrient deficiencies and would benefit from this knowledge (in which case I’m still confused why you wrote this post instead of just presenting this information)
The health harms of nutrient deficiencies in veganism are more serious than is widely recognised
There are serious health harms of veganism other than the risk of nutrient deficiencies that are known but this knowledge is not widespread, or that we don’t know about yet but have good reason to suspect exist
This feels very epistemically cooperative, thank you.
The answer is primarily point 1, although whether that’s distinct from point 2 depends on the definition of “widely recognized” . Which brings me to your question:
in which case I’m still confused why you wrote this post instead of just presenting this information
The answer is that I did present the information, and proactively provided help, and I got pushback that only made sense if people disagreed with “veganism is a constraint on a multidimensional problem”. But they would never defend that position. Announcing my own view and asking for counter-evidence was my Plan C after “offering help” and “asking why certain people thought that help was harmful” failed.
Thanks, this and your comment here helped a lot to clarify your position and intentions. My initial impression was similar to Natália’s, i.e. that you believed something more like point 3.
Re. point 2, by “widely recognised” (and similarly for “widespread” in point 3) I meant something like “widely recognised in relevant academic literature/textbooks/among experts” rather than “among people who have ever tried a vegan diet”. My impression is that on this definition you wouldn’t endorse point 2 either.
We may still disagree on the “importance” of point 1, although to be clear I completely support any effort to inform vegans or potential vegans about the risk of nutrient deficiencies. It’s probably not possible or worth the effort to resolve this disagreement, but it does make me wonder about:
Could at least some of these encounters be explained by a similar “disagreement about importance”, as opposed to disagreement about the basic facts? That might explain why these exchanges seemed obfuscated or un-cooperative; you thought they were evading obvious facts, while they thought you were making mountains out of (what they saw as) molehills.
I don’t think anyone thought “oh, Elizabeth’s statement is obviously true but I will argue with her and make obviously false claims” while twirling a mustache. That’s not how people work. But I also think my words were extremely clear, and if they’re being misread this often there’s a systemic problem in the readers.
I realize this is a big claim; frequent misunderstandings are by default the fault of the author. But a lot of people got it, and I don’t know what I could have done to get a different outcome. You can argue the framing of the post was suspicious, and I can see why that would be true for this post and why it would make people overly aggressive in rebuttals. But what about when I was offering nutritional tests and vegan supplements? And that one was at least pretty overt, some private ones were mental jui-jitsu to which my only defense was stating my own opinions very plainly.
Relatedly: this is not my first time asking for this evidence. Every time I posted installments of my nutrition testing program, someone would say “this sample size is too small” and I’d say “you are correct, do you know of anything better?”, and nothing would come of it. It took this post for someone to send me the 7th Day Adventist data.
So if I focus on productively treating the object level problem, people push back in ways that can’t be argued with because they’re not epistemically cooperative. If I try to engage in a way that feels epistemically tractable, people get even angrier and impugn my motives more.
Given the context I laid out, is there anything I could have done to create a more productive discussion with you, personally?
That is a frustrating situation. As you note in the introduction this is a charged topic that tends to lead to poor discussions, so you deserve credit for wading in anyway.
Given the context I laid out, is there anything I could have done to create a more productive discussion with you, personally?
I’m not sure. The discussion in this comment thread (andothers) has been productive in the sense that I now have a much better understanding of your position and the context. In terms of the original post, I don’t know if a one-sentence summary would have changed much; given my impression of the post it might have looked like an attempt to motte-and-bailey. I could try to break down why the post gave me the impression it did, if you think that would be useful.
Thank you for the empathy, this has been extremely challenging.
I think something similar to “why the post gave you the impression it did” could be helpful, and I’m even more interested in what you think could be done to convey the important, true points with as little animosity-due-to-misreading as possible
Thoughts on why the post gave (me) the impression it did, in no particular order:
‘Trade-offs’ is broad and vague, and the post didn’t make a lot of detailed claims about vegan nutrition. This makes sense in the context of you trying to communicate the detailed facts previously, but coming to the post without that context made it hard to tell if you were just making an unobjectionable claim or trying to imply something broader.
Some statements struck me as technically true but hyperbolic. Examples:
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.
[...]
Some people are already struggling to feed themselves on an omnivore diet, and have nothing to replace meat if you take it away.
[...]
If vegans are equally healthy but are spending twice as much time and money on food, that’s important to know.
[...]
If there are three vegan sources and you’re allergic to all of them, you need animal products.
I was very confused by what you were hoping to learn from an RCT or ‘good study’, and my impression of your in-office nutritional testing was that you were trying to gather new primary data about vegan nutrition. Because the basic facts about the risk of nutrient deficiencies in veganism seemed uncontroversial, my interpretation of that was that you thought there were other and potentially more significant ‘trade-offs’ that might exist at the level-of-evidence gap between an RCT or in-office testing and e.g. the introduction to the Wikipedia article on veganism.
The implied model for the relationship between diet and health felt...off, or at least different from my own. I tend to think of diet as an input to a set of homeostatic processes, which are generally robust but can be slowly pushed off-balance by sustained problems and usually fixed with gentle correction. This post seemed to model diet as an all-or-nothing ‘logic puzzle’ to be either solved or, more likely, failed.
...what you think could be done to convey the important, true points with as little animosity-due-to-misreading as possible
Beyond the points above, I genuinely don’t know. I’m probably not the intended audience anyway, since that seems to be vegans or potential vegans who don’t already know about the risks of nutrient deficiencies. The only thing I can think to contribute here is: if you’ve tried presenting the basic facts of the matter, and experienced pushback for it, does that necessarily mean that just presenting the facts is the wrong strategy? It’s a charged topic with a polluted local memespace, so some level of malicious or confused pushback is guaranteed; it’s what you would expect to see even when you are communicating well.
if you’ve tried presenting the basic facts of the matter, and experienced pushback for it, does that necessarily mean that just presenting the facts is the wrong strategy?
If people are very convinced I’m wrong then asking them why seems like a great strategy to me. They might be right and that might have implications for my plans. The point of this post wasn’t to convince anyone, it was to ask for evidence on a specific question.
I’m really glad we got to a more cooperative space and I hate to puncture that, but two weeks later I’m still kind of aghast you said “If you take out the references to veganism, this is just the current state of the world. People advertise their fast food restaurants and feed their children sugary breakfast cereals without caveats about the risk of heart disease or diabetes.” Surely you don’t think that’s the right moral category for ethical veganism?
Surely you don’t think that’s the right moral category for ethical veganism?
I don’t really understand what you’re asking here. How would you describe the moral category you’re referring to, and why do you think it doesn’t or shouldn’t apply to veganism?
McDonalds and sugary cereal advertisers are widely viewed as harmful if not evil for the way they confuse the epistemic environment in order to make money and others’ expense. Calling something “no worse than fast food and sugary cereal advertisers” is an enormous moral and epistemic insult to it.
I absolutely agree. McDonalds and the other demons of the Western Diet cause much more harm, both in absolute terms and per capita. That was really my point; within the class of ‘health misinformation and disinformation that causes harm’, furphies about vegan nutrition are a comparatively minor problem.
This sounds like you’re saying “I won’t prescribe B12 until my patient gives up oreos” or even “I won’t prescribe B12 until everyone gives up oreos”, which would be an awful way to treat people. Even if you’re right that oreos represent a larger problem, taking B12 pills is useful in its own right, and easier than giving up oreos[1].
I assume you don’t mean that. You probably mean “I don’t think Elizabeth/anyone should spend time on veganism’s problems, when metabolic issues are doing so much more aggregate harm.” But tractability applies even more on a population level. People aren’t eating oreos out of ignorance: they know they’re bad. They eat them because taste is winning out over health.
It’s impossible for a blog post to fix “oreos taste good” or “people care more about taste than health”. But it’s pretty easy theoretically possible for a blog post to fix ignorance of the benefits of some tests and supplements. When I see similarly tractable opportunities to help omnivores, I take them.
Hell, I found a (vegan) cure for oreos tasting good (n=1). Finding it took years of self-experimentation (where the iron post took a few days, for more certainly). AFAIK no one else has tried it, because it takes consistent effort over several months to see an effect on weight[2].
So no, I am not going to let McDonalds shitty advertising hold up alerting people to problems with simple diagnoses with simple solutions
It also costs $5-$10/day, but I know people jumping through a lot of hoops to get semaglutide, so I’m pretty sure the issue here is the delay and uncertainty.
This sounds like you’re saying “I won’t prescribe B12 until my patient gives up oreos” or even “I won’t prescribe B12 until everyone gives up oreos”, which would be an awful way to treat people.[1]
[...]
You probably mean “I don’t think Elizabeth/anyone should spend time on veganism’s problems, when metabolic issues are doing so much more aggregate harm.”
I wouldn’t say either of these things. A quick and easy treatment like B12 replacement is not mutually exclusive with a long-term and difficult treatment like diet modification. (This is not an abstract question for me; prescribing a statin and counselling on lifestyle changes are both things I do several times a week, and of the two, the script is orders of magnitude easier for both me and the patient, but we’ll usually do both in parallel when treating dyslipidaemia.)
As I said earlier in the thread, I’m all in favour of you or anybody else spending time on making people aware of the risk of nutrient deficiencies associated with veganism and what to do about them. (Again, this is not an abstract issue to me; I routinely discuss, screen for, and treat nutrient deficiencies with vegan and vegetarian patients.) I do recognise that you’ve had some bad experiences doing this, which is unfair.
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.
I don’t doubt the Faunalytics data. If anything the number seems surprisingly low, considering it comes from self-reporting among people who went on to quit veganism.
I’m not sure how to weigh ‘importance’ other than subjectively, but I’ll attempt to at least put bounds on it. As a floor, some number of people experience health issues that are important enough to them that they are motivated to quit veganism. As a ceiling, the health risks of veganism are less important than those of other harms related to diet – for example, dyslipidaemia or diabetes – that increase mortality, given that veganism doesn’t seem to increase mortality and may reduce it.
My stance at the moment is still more ‘generally confused about what you’re trying to communicate/achieve’ than ‘disagreeing with a particular claim you’re making’. I’d like to close the inferential distance if possible, but feel free to ignore this comment if you don’t think it’s leading anywhere useful.
I still don’t understand which of the following (if any) you would endorse:
Many vegans don’t know about the risk of nutrient deficiencies and would benefit from this knowledge (in which case I’m still confused why you wrote this post instead of just presenting this information)
The health harms of nutrient deficiencies in veganism are more serious than is widely recognised
There are serious health harms of veganism other than the risk of nutrient deficiencies that are known but this knowledge is not widespread, or that we don’t know about yet but have good reason to suspect exist
This feels very epistemically cooperative, thank you.
The answer is primarily point 1, although whether that’s distinct from point 2 depends on the definition of “widely recognized” . Which brings me to your question:
The answer is that I did present the information, and proactively provided help, and I got pushback that only made sense if people disagreed with “veganism is a constraint on a multidimensional problem”. But they would never defend that position. Announcing my own view and asking for counter-evidence was my Plan C after “offering help” and “asking why certain people thought that help was harmful” failed.
Thanks, this and your comment here helped a lot to clarify your position and intentions. My initial impression was similar to Natália’s, i.e. that you believed something more like point 3.
Re. point 2, by “widely recognised” (and similarly for “widespread” in point 3) I meant something like “widely recognised in relevant academic literature/textbooks/among experts” rather than “among people who have ever tried a vegan diet”. My impression is that on this definition you wouldn’t endorse point 2 either.
We may still disagree on the “importance” of point 1, although to be clear I completely support any effort to inform vegans or potential vegans about the risk of nutrient deficiencies. It’s probably not possible or worth the effort to resolve this disagreement, but it does make me wonder about:
and:
Could at least some of these encounters be explained by a similar “disagreement about importance”, as opposed to disagreement about the basic facts? That might explain why these exchanges seemed obfuscated or un-cooperative; you thought they were evading obvious facts, while they thought you were making mountains out of (what they saw as) molehills.
I feel like I’m in a bit of a trap here.
I don’t think anyone thought “oh, Elizabeth’s statement is obviously true but I will argue with her and make obviously false claims” while twirling a mustache. That’s not how people work. But I also think my words were extremely clear, and if they’re being misread this often there’s a systemic problem in the readers.
I realize this is a big claim; frequent misunderstandings are by default the fault of the author. But a lot of people got it, and I don’t know what I could have done to get a different outcome. You can argue the framing of the post was suspicious, and I can see why that would be true for this post and why it would make people overly aggressive in rebuttals. But what about when I was offering nutritional tests and vegan supplements? And that one was at least pretty overt, some private ones were mental jui-jitsu to which my only defense was stating my own opinions very plainly.
Relatedly: this is not my first time asking for this evidence. Every time I posted installments of my nutrition testing program, someone would say “this sample size is too small” and I’d say “you are correct, do you know of anything better?”, and nothing would come of it. It took this post for someone to send me the 7th Day Adventist data.
So if I focus on productively treating the object level problem, people push back in ways that can’t be argued with because they’re not epistemically cooperative. If I try to engage in a way that feels epistemically tractable, people get even angrier and impugn my motives more.
Given the context I laid out, is there anything I could have done to create a more productive discussion with you, personally?
That is a frustrating situation. As you note in the introduction this is a charged topic that tends to lead to poor discussions, so you deserve credit for wading in anyway.
I’m not sure. The discussion in this comment thread (and others) has been productive in the sense that I now have a much better understanding of your position and the context. In terms of the original post, I don’t know if a one-sentence summary would have changed much; given my impression of the post it might have looked like an attempt to motte-and-bailey. I could try to break down why the post gave me the impression it did, if you think that would be useful.
Thank you for the empathy, this has been extremely challenging.
I think something similar to “why the post gave you the impression it did” could be helpful, and I’m even more interested in what you think could be done to convey the important, true points with as little animosity-due-to-misreading as possible
Thoughts on why the post gave (me) the impression it did, in no particular order:
‘Trade-offs’ is broad and vague, and the post didn’t make a lot of detailed claims about vegan nutrition. This makes sense in the context of you trying to communicate the detailed facts previously, but coming to the post without that context made it hard to tell if you were just making an unobjectionable claim or trying to imply something broader.
Some statements struck me as technically true but hyperbolic. Examples:
I was very confused by what you were hoping to learn from an RCT or ‘good study’, and my impression of your in-office nutritional testing was that you were trying to gather new primary data about vegan nutrition. Because the basic facts about the risk of nutrient deficiencies in veganism seemed uncontroversial, my interpretation of that was that you thought there were other and potentially more significant ‘trade-offs’ that might exist at the level-of-evidence gap between an RCT or in-office testing and e.g. the introduction to the Wikipedia article on veganism.
The implied model for the relationship between diet and health felt...off, or at least different from my own. I tend to think of diet as an input to a set of homeostatic processes, which are generally robust but can be slowly pushed off-balance by sustained problems and usually fixed with gentle correction. This post seemed to model diet as an all-or-nothing ‘logic puzzle’ to be either solved or, more likely, failed.
Beyond the points above, I genuinely don’t know. I’m probably not the intended audience anyway, since that seems to be vegans or potential vegans who don’t already know about the risks of nutrient deficiencies. The only thing I can think to contribute here is: if you’ve tried presenting the basic facts of the matter, and experienced pushback for it, does that necessarily mean that just presenting the facts is the wrong strategy? It’s a charged topic with a polluted local memespace, so some level of malicious or confused pushback is guaranteed; it’s what you would expect to see even when you are communicating well.
If people are very convinced I’m wrong then asking them why seems like a great strategy to me. They might be right and that might have implications for my plans. The point of this post wasn’t to convince anyone, it was to ask for evidence on a specific question.
I’m really glad we got to a more cooperative space and I hate to puncture that, but two weeks later I’m still kind of aghast you said “If you take out the references to veganism, this is just the current state of the world. People advertise their fast food restaurants and feed their children sugary breakfast cereals without caveats about the risk of heart disease or diabetes.” Surely you don’t think that’s the right moral category for ethical veganism?
I don’t really understand what you’re asking here. How would you describe the moral category you’re referring to, and why do you think it doesn’t or shouldn’t apply to veganism?
McDonalds and sugary cereal advertisers are widely viewed as harmful if not evil for the way they confuse the epistemic environment in order to make money and others’ expense. Calling something “no worse than fast food and sugary cereal advertisers” is an enormous moral and epistemic insult to it.
I absolutely agree. McDonalds and the other demons of the Western Diet cause much more harm, both in absolute terms and per capita. That was really my point; within the class of ‘health misinformation and disinformation that causes harm’, furphies about vegan nutrition are a comparatively minor problem.
This sounds like you’re saying “I won’t prescribe B12 until my patient gives up oreos” or even “I won’t prescribe B12 until everyone gives up oreos”, which would be an awful way to treat people. Even if you’re right that oreos represent a larger problem, taking B12 pills is useful in its own right, and easier than giving up oreos[1].
I assume you don’t mean that. You probably mean “I don’t think Elizabeth/anyone should spend time on veganism’s problems, when metabolic issues are doing so much more aggregate harm.” But tractability applies even more on a population level. People aren’t eating oreos out of ignorance: they know they’re bad. They eat them because taste is winning out over health.
It’s impossible for a blog post to fix “oreos taste good” or “people care more about taste than health”. But it’s
pretty easytheoretically possible for a blog post to fix ignorance of the benefits of some tests and supplements. When I see similarly tractable opportunities to help omnivores, I take them.Hell, I found a (vegan) cure for oreos tasting good (n=1). Finding it took years of self-experimentation (where the iron post took a few days, for more certainly). AFAIK no one else has tried it, because it takes consistent effort over several months to see an effect on weight[2].
So no, I am not going to let McDonalds shitty advertising hold up alerting people to problems with simple diagnoses with simple solutions
Especially by the time someone is in the doctor’s office for oreo-related problems. The people who find oreos easy to give up have already done so.
It also costs $5-$10/day, but I know people jumping through a lot of hoops to get semaglutide, so I’m pretty sure the issue here is the delay and uncertainty.
I wouldn’t say either of these things. A quick and easy treatment like B12 replacement is not mutually exclusive with a long-term and difficult treatment like diet modification. (This is not an abstract question for me; prescribing a statin and counselling on lifestyle changes are both things I do several times a week, and of the two, the script is orders of magnitude easier for both me and the patient, but we’ll usually do both in parallel when treating dyslipidaemia.)
As I said earlier in the thread, I’m all in favour of you or anybody else spending time on making people aware of the risk of nutrient deficiencies associated with veganism and what to do about them. (Again, this is not an abstract issue to me; I routinely discuss, screen for, and treat nutrient deficiencies with vegan and vegetarian patients.) I do recognise that you’ve had some bad experiences doing this, which is unfair.
I’m not sure if you chose this example intentionally, but for what it’s worth: Oreos are vegan.
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.