Thanks for this post! I’m currently transitioning to a vegetarian diet, and am considering doing or trying a vegan diet in the future. So the title of this post was something I’ve thought about. I’m glad to see someone compile a literature review on this question.
I guess one question though that health-conscious meat-eaters might still ask after reading this is, “Okay a vegan diet is healthy, but I want to have the healthiest diet. Wouldn’t the healthiest diet for humans be one that is not vegan?”
I am not a nutritionist but my very brief look at the opinions of expert and enthusiast nutritionists and the studies they cite has told me that the healthiest diet is probably not vegetarian.
First, not all animal products are equal, and the oft-touted pro-veg*n studies overlook these differences. Many of the supposed benefits of veg*n diets seem to come from the exclusion of processed meat, which is meat that has been treated with modern preservatives, flavorings, etc. This is really backed up by studies, not just anti-artificial sentiment. Good studies looking at the health impacts of unprocessed meat (which, I believe, generally includes ground beef) are rare. I’ve only found one, a cohort study, and it did find that unprocessed red meat increased mortality, but not as much as processed red meat. Whether unprocessed white meat and fish have detrimental impacts seems like a very open question. And even when it comes to red meat, nutritional findings that were backed by similarly strong evidence as this have been overturned in the past, I believe. Then there are a select few types of meat which seem particularly healthy, like sardines, liver and marrow, and there is still less reason to believe that they are harmful. Moving on to dairy products, it seems that fermented dairy products are significantly superior to nonfermented ones.
Second, vegan diets miss out on creatine, omega-3 fat in its proper EHA/DHA form, Vitamin D, taurine, and carnosine. Dietary intake of these is not generally necessary for a basically decent life as far as I know, but being fully healthy (longest working life + highest chance of living to a longevity horizon + best cognitive function) is a different story, and these chemicals are variously known or hypothesized to be beneficial. You can of course supplement, but at the cost of extra time and money—and that’s assuming that you remember to supplement. For some people who are simply bad at keeping habits—me, at least—supplementing for an important nutrient just isn’t a reliable option; I can set my mind to do it but I predictably fail to keep up with it.
Third, vegan/vegetarian diets reduce your flexibility to make other healthy changes. As an omnivore, it’s pretty easy for me to minimize or avoid unhealthy foods such as store-bought bread (with so many preservatives, flavorings etc) and fortified cereal. As a vegetarian or vegan, this would be significantly more difficult. When I was vegan and when I was vegetarian, both times I made it work by eating some less-than-healthy foods, otherwise I would have had to face greater time and/or money spent on putting my diet together.
Finally, nutritional science is frankly a terrible mess, and not necessarily due to ill motives and practices on the part of researchers (though there is some of that) but also because of just how difficult it is to tease out correlation from causation in this business. There’s a lot that we don’t understand, including chemicals that may play a valuable health role but haven’t been properly identified as such. Therefore, in the absence of clear guidance it’s wise to defer to eating (a) a wide variety of foods, which is enhanced by including animal products, and (b) foods that we evolved to eat, which has usually included at least a small amount of meat.
For these reasons, I weakly feel that the healthiest diet will include some meat and/or fish, and feel it more strongly if we consider that someone is spending only a limited amount of time and money on their diet. Of course that doesn’t mean that a typical Western omnivorous diet is superior to a typical Western veg*n diet (it probably isn’t).
I’m curious to hear if you have any thoughts on this!
Ah, good question. Like the author of your quote, I’m also not a nutritionist, nor am I a medical doctor. That said, I wouldn’t be surprised if the healthiest diet did include some animal products. That’s because vegan/vegetarian diets optimise for something else – they optimise for the removal of meat & animal products. It shouldn’t be surprising that a diet optimising purely for health might be better than (& different from) one that optimises for something else entirely.
I suppose in the end one has to sort out one’s motivations in choosing a diet. How much importance do I place on my health versus, say, animal suffering? (Or, in more deontological terms, how do I reconcile the duties I have to myself with those I have to other creatures?) Personally, I would strive to eat vegan/vegetarian even if I learned that it was relatively unhealthy. But I’m well aware that not everyone would do that!
Yeah what you said makes sense. I agree that I think practically everyone who can should go for a vegetarian/vegan diet even if it is not the healthiest one. It’s already good enough that it’s likely a healthier diet compared to most people’s diets. Thanks for your thoughts!
You can optimise for health on a vegan diet as well. The only difference would be any nutrients that are exclusively found in animal products. But, as I stated in my other comment below, I think there are good reasons to believe that it’s unlikely there are any such nutrients with non-negligible health benefits, other than those that we are aware of and can be supplemented. The main reason is all the knowledge we collectively have about the nutrients in the human diet (and the compounds which are important for metabolism in the human body).
I know this is very late, but I felt obliged to reply since I disagree with a lot of the points made in the post you quoted.
First, not all animal products are equal, and the oft-touted pro-veg*n studies overlook these differences. Many of the supposed benefits of veg*n diets seem to come from the exclusion of processed meat, which is meat that has been treated with modern preservatives, flavorings, etc. This is really backed up by studies, not just anti-artificial sentiment. Good studies looking at the health impacts of unprocessed meat (which, I believe, generally includes ground beef) are rare.
Unprocessed red meat is still classified as a type 2A carcinogen by the WHO’s IARC (International Agency for Research on Cancer), meaning it is ‘probably carcinogenic’. Also, fish and other seafood are known to contain relatively high levels of mercury, meaning there are health issues associated with consuming them too much.
Additionally, saturated and trans fats are almost ubiquitous in animal products, often at relatively high levels. Both of these are widely considered to be unhealthy. Indeed, the NAS (Nutritional Academy of Sciences) in the US has stated that there is no safe level of trans fat consumption.
Then there are a select few types of meat which seem particularly healthy, like sardines, liver and marrow, and there is still less reason to believe that they are harmful.
Levels of cadmium (another toxic metal) seem to be typically higher in offal, like liver, than in plant foods (source). This is somewhat unsurprising as heavy metals tend to accumulate in the liver when animals are trying to metabolise them. Also, it seems like if consuming a decent amount of liver would lead to getting far too much of some vitamins and minerals, which is generally not good (e.g. see these composition data).
Second, vegan diets miss out on creatine, omega-3 fat in its proper EHA/DHA form, Vitamin D, taurine, and carnosine.
Humans are very capable of converting ALA (the predominant omega-3 fatty acid found in plant foods) to EPA and DHA (source). It is not hard to get the amount of ALA required for sufficient EPA and DHA, even assuming a somewhat low conversion rate. This amount would typically be a few grams per day. Also, the conversion rate is taken into account in all nutritional guidelines.
Taurine is synthesised in the human body from cysteine. Carnosine is synthesised from histidine, cytosine and uracil. Cysteine and histidine are both found in high amounts in plant proteins (source), while cytosine and uracil, being nucleotide bases, are quite ubiquitous in the body. I think it is reasonable to assume that the human body will produce the amount of taurine and carnosine required for optimal health, even without obtaining them through a diet, and I would place a high prior probability on that. Additionally, the evidence so far suggests that there are not health benefits from having dietary intake or higher levels of these compounds.
For creatine the evidence is a little more mixed, although the majority of evidence still suggests that dietary intake does not provide health benefits. Nonetheless, one may want to supplement it out of an abundance of caution.
You can of course supplement, but at the cost of extra time and money
I don’t think supplementing generally takes more than ~5 minutes extra per day. And generally I find that supplements are a fairly negligible expense. (This is especially the case because some brands have very high amounts of the nutrients in their products and personally I often break up the tablets into smaller proportions.) I can add some more information about costs here if anyone is interested.
For some people who are simply bad at keeping habits—me, at least—supplementing for an important nutrient just isn’t a reliable option; I can set my mind to do it but I predictably fail to keep up with it.
I think anyone who can maintain a typical lifestyle is good enough at keeping habits to utilise supplementation. (Not criticising the OP—maybe they just needed a bit more time to get used to it.) Nonetheless, foods fortified with nutrients like vitamin B12 and vitamin D are widely available, so one could simply use those instead. If this also isn’t an option for some reason, you could just take larger amounts of the supplements once every few days or even once a week, depending on the elimination half-life of the nutrient. To my knowledge, this would work for vitamin B12 and vitamin D (although not for creatine apparently).
Third, vegan/vegetarian diets reduce your flexibility to make other healthy changes. As an omnivore, it’s pretty easy for me to minimize or avoid unhealthy foods such as store-bought bread (with so many preservatives, flavorings etc) and fortified cereal.
Preservatives and flavourings (and additives in general) are not automatically unhealthy, and indeed most of them are perfectly healthy, as they have to pass rigorous safety standards before being approved (and they are generally studied extensively even after they’re approved). As such, store-bought bread and fortified cereals are not unhealthy either, and I would say they’re actually good components of a diet. However, if anyone wants to share evidence to the contrary, feel free.
As a vegetarian or vegan, [avoiding unhealthy foods] would be significantly more difficult.
I find that vegetarian or vegan products are often healthier than the alternatives. This is probably because there seems to be a frequent association between plant-based foods and healthiness in marketing, e.g. because companies think the target demographics overlap significantly (which I could imagine being true).
Finally, nutritional science is frankly a terrible mess, and not necessarily due to ill motives and practices on the part of researchers (though there is some of that) but also because of just how difficult it is to tease out correlation from causation in this business. There’s a lot that we don’t understand, including chemicals that may play a valuable health role but haven’t been properly identified as such. Therefore, in the absence of clear guidance it’s wise to defer to eating (a) a wide variety of foods, which is enhanced by including animal products, and (b) foods that we evolved to eat, which has usually included at least a small amount of meat.
I think this is the strongest argument in the post. However I want to point out that nutrition as a field has existed for a long time and by now we have characterised and studied the majority of nutrients that are present in typical human diets. It seems unlikely that there are nutrients we are unaware of that are exclusively present in animal products and have non-negligible health benefits (from dietary intake). Additionally, there are cohort studies which measure a large number of health outcomes for omnivores and vegetarians and/or vegans, and they haven’t identified any particular negative effects from either of the latter (indeed it’s usually the other way around). The main disadvantage I can think of there is that these studies don’t measure every possible health outcome that may be relevant.
For these reasons, I weakly feel that the healthiest diet will include some meat and/or fish, and feel it more strongly if we consider that someone is spending only a limited amount of time and money on their diet. Of course that doesn’t mean that a typical Western omnivorous diet is superior to a typical Western veg*n diet (it probably isn’t).
I can understand that there may be a small negative expected value from nutrients lacking in a vegan diet that we are currently unaware of. However I think this is plausibly outweighed by the negative expected value from some of the health effects (e.g. those above) that are associated with most animal products, given that these are more probable and seemingly more serious.
Or, to put this another way, your prior for the best diet containing some animal products might initially be quite high, but in light of the evidence against the healthiness of many animal products, I think the probability becomes quite low.
That being said, I disagree that it takes more time and money to create an optimal (or just reasonably good) vegan diet than an optimal omnivorous diet, for reasons listed above, and because I think the latter is significantly more difficult than one might intuitively believe.
Thanks for this post! I’m currently transitioning to a vegetarian diet, and am considering doing or trying a vegan diet in the future. So the title of this post was something I’ve thought about. I’m glad to see someone compile a literature review on this question.
I guess one question though that health-conscious meat-eaters might still ask after reading this is, “Okay a vegan diet is healthy, but I want to have the healthiest diet. Wouldn’t the healthiest diet for humans be one that is not vegan?”
It would probably be hard to find out what is the healthiest diet for humans from existing literature, but I’ve seen someone argue in this forum that the healthiest diet is probably not vegetarian:
I’m curious to hear if you have any thoughts on this!
Ah, good question. Like the author of your quote, I’m also not a nutritionist, nor am I a medical doctor. That said, I wouldn’t be surprised if the healthiest diet did include some animal products. That’s because vegan/vegetarian diets optimise for something else – they optimise for the removal of meat & animal products. It shouldn’t be surprising that a diet optimising purely for health might be better than (& different from) one that optimises for something else entirely.
I suppose in the end one has to sort out one’s motivations in choosing a diet. How much importance do I place on my health versus, say, animal suffering? (Or, in more deontological terms, how do I reconcile the duties I have to myself with those I have to other creatures?) Personally, I would strive to eat vegan/vegetarian even if I learned that it was relatively unhealthy. But I’m well aware that not everyone would do that!
Yeah what you said makes sense. I agree that I think practically everyone who can should go for a vegetarian/vegan diet even if it is not the healthiest one. It’s already good enough that it’s likely a healthier diet compared to most people’s diets. Thanks for your thoughts!
You can optimise for health on a vegan diet as well. The only difference would be any nutrients that are exclusively found in animal products. But, as I stated in my other comment below, I think there are good reasons to believe that it’s unlikely there are any such nutrients with non-negligible health benefits, other than those that we are aware of and can be supplemented. The main reason is all the knowledge we collectively have about the nutrients in the human diet (and the compounds which are important for metabolism in the human body).
I know this is very late, but I felt obliged to reply since I disagree with a lot of the points made in the post you quoted.
Unprocessed red meat is still classified as a type 2A carcinogen by the WHO’s IARC (International Agency for Research on Cancer), meaning it is ‘probably carcinogenic’. Also, fish and other seafood are known to contain relatively high levels of mercury, meaning there are health issues associated with consuming them too much.
Additionally, saturated and trans fats are almost ubiquitous in animal products, often at relatively high levels. Both of these are widely considered to be unhealthy. Indeed, the NAS (Nutritional Academy of Sciences) in the US has stated that there is no safe level of trans fat consumption.
Levels of cadmium (another toxic metal) seem to be typically higher in offal, like liver, than in plant foods (source). This is somewhat unsurprising as heavy metals tend to accumulate in the liver when animals are trying to metabolise them. Also, it seems like if consuming a decent amount of liver would lead to getting far too much of some vitamins and minerals, which is generally not good (e.g. see these composition data).
Humans are very capable of converting ALA (the predominant omega-3 fatty acid found in plant foods) to EPA and DHA (source). It is not hard to get the amount of ALA required for sufficient EPA and DHA, even assuming a somewhat low conversion rate. This amount would typically be a few grams per day. Also, the conversion rate is taken into account in all nutritional guidelines.
Taurine is synthesised in the human body from cysteine. Carnosine is synthesised from histidine, cytosine and uracil. Cysteine and histidine are both found in high amounts in plant proteins (source), while cytosine and uracil, being nucleotide bases, are quite ubiquitous in the body. I think it is reasonable to assume that the human body will produce the amount of taurine and carnosine required for optimal health, even without obtaining them through a diet, and I would place a high prior probability on that. Additionally, the evidence so far suggests that there are not health benefits from having dietary intake or higher levels of these compounds.
For creatine the evidence is a little more mixed, although the majority of evidence still suggests that dietary intake does not provide health benefits. Nonetheless, one may want to supplement it out of an abundance of caution.
I don’t think supplementing generally takes more than ~5 minutes extra per day. And generally I find that supplements are a fairly negligible expense. (This is especially the case because some brands have very high amounts of the nutrients in their products and personally I often break up the tablets into smaller proportions.) I can add some more information about costs here if anyone is interested.
I think anyone who can maintain a typical lifestyle is good enough at keeping habits to utilise supplementation. (Not criticising the OP—maybe they just needed a bit more time to get used to it.) Nonetheless, foods fortified with nutrients like vitamin B12 and vitamin D are widely available, so one could simply use those instead. If this also isn’t an option for some reason, you could just take larger amounts of the supplements once every few days or even once a week, depending on the elimination half-life of the nutrient. To my knowledge, this would work for vitamin B12 and vitamin D (although not for creatine apparently).
Preservatives and flavourings (and additives in general) are not automatically unhealthy, and indeed most of them are perfectly healthy, as they have to pass rigorous safety standards before being approved (and they are generally studied extensively even after they’re approved). As such, store-bought bread and fortified cereals are not unhealthy either, and I would say they’re actually good components of a diet. However, if anyone wants to share evidence to the contrary, feel free.
I find that vegetarian or vegan products are often healthier than the alternatives. This is probably because there seems to be a frequent association between plant-based foods and healthiness in marketing, e.g. because companies think the target demographics overlap significantly (which I could imagine being true).
I think this is the strongest argument in the post. However I want to point out that nutrition as a field has existed for a long time and by now we have characterised and studied the majority of nutrients that are present in typical human diets. It seems unlikely that there are nutrients we are unaware of that are exclusively present in animal products and have non-negligible health benefits (from dietary intake). Additionally, there are cohort studies which measure a large number of health outcomes for omnivores and vegetarians and/or vegans, and they haven’t identified any particular negative effects from either of the latter (indeed it’s usually the other way around). The main disadvantage I can think of there is that these studies don’t measure every possible health outcome that may be relevant.
I can understand that there may be a small negative expected value from nutrients lacking in a vegan diet that we are currently unaware of. However I think this is plausibly outweighed by the negative expected value from some of the health effects (e.g. those above) that are associated with most animal products, given that these are more probable and seemingly more serious.
Or, to put this another way, your prior for the best diet containing some animal products might initially be quite high, but in light of the evidence against the healthiness of many animal products, I think the probability becomes quite low.
That being said, I disagree that it takes more time and money to create an optimal (or just reasonably good) vegan diet than an optimal omnivorous diet, for reasons listed above, and because I think the latter is significantly more difficult than one might intuitively believe.