One of my criticisms of this original post is that with the vegan diet there can be uncertainty over what you may be missing on a vegan diet, but with a lot of animal food there is uncertainty over what you may be getting, and for me there are many concerns about pollutants in oysters. I would prefer a vegan multivitamin.

Fifteen years later, I am glad I read this. Great comment, DanArmak.

> First off, even the most dedicated vegans will tell you that to stay vegan you need to take medicine to not die - B12.

It is not controversial that vegans should take supplements, and vitamin B12 is the most important. However, taking supplements does not make a diet inherently unhealthy.

When people argue that veganism is "unnatural" or "difficult" because it needs supplementation (e.g. B12), they assume the current food environment is neutral. However, the current food environment has been shaped by centuries of cultural, economic, and technological reinforcement of animal agriculture.

If hypothetically we are born into a culture where plant foods are fortified by default with B12 (as salt is with iodine or bread with folate), if vegan diets were standard in childhood education and food manufacturing, and family traditions were built around the vegan diet, then supplementation would be routine and uncontroversial as iodised salt or vitamin D fortification is today.

The term "supplement" is not an objective marker of artificiality but rather it is a social label. The distinction between "food" and "supplement" is culturally constructed. As mentioned, we have already fortified many foods to prevent deficiency e.g. iodine in salt, folate in bread, B vitamins in cereal, vitamin D in milk. We also feed supplements to factory farmed animals. That is, most factory farmed animals are fed B12, vitamin D, and mineral mixes since intensive farming depletes their natural diets. When omnivores eat meat, they are indirectly supplementing via the animal. The animals are the middlemen for your supplements.

So veganism is not necessarily harder but just less normalised. The infrastructure and norms currently are aligned to an omnivorous diet. Looking at it like this, the idea the "veganism requires supplements" critique is less about biology and more about status quo bias i.e. a psychological tendency to see whatever is currently normal as natural, easy and superior.

Even within today’s norms, a vegan can re-socialise themselves. By learning the basics of nutrition and supplementation, a vegan can adapt. This is no different than learning to drive, manage finances, or cook healthy meals.

So while veganism currently feels harder, that’s a temporary artifact of culture and norms — not evidence of the diet's intrinsic inferiority.

> I highly recommend Michael Pollan’s book, In Defense of Food. It’s basically about the meta field of nutrition and how little we know, how most of nutrition science is fundamentally difficult, and is just one giant case for epistemic humility when it comes to nutrition.

Regarding the argument that if you go on a vegan diet, you may miss something, the implicit assumption here is that the omnivorous diet is complete by default.

An "unknown unknown" is something you don't know that you don't know. Applied to the vegan diet, the argument is that there is a possibility that there is something missing in the vegan diet that we don't know about. However, the "unknown unknown" problem works the other way as well e.g. what if eating animal products introduces some chemical that is harmful but we don't know it is harmful? For example, how do we know that animal proteins high in the amino acids leucine and methionine won't cause accelerated ageing? The science on this is evolving. If we apply the precautionary principle on veganism saying it may be missing something we don't know about that is important, we can apply the precautionary principle on omnivorous diets saying it may contain something we don't know is harmful.

No diet can eliminate all unknown risks, so the best approach is to rely on the current best evidence, monitor biomarkers, minimise known harms, and remain open to updating our understanding as the science progresses.

From that perspective, veganism isn’t uniquely vulnerable, but it’s just one dietary framework that must be managed thoughtfully, as all should be.

The fair stance is epistemic humility for all diets rather than selective skepticism toward veganism.

> Not to mention that of all of the hunter gatherer tribes ever studied, there has never been a single vegetarian group discovered. Not. A. Single. One.

The world has changed significantly since hunter gatherer tribes were on this planet. For example, rather than hunting wild animals, most meat now comes from industrialised factory farms, and there are far more pollutants in oceans where fish swim e.g. mercury, cadmium, and microplastics. As such there is no reason to believe that what humans ate in the past is the same as what we eat now.

Also there is an assumption here that evolution selected for optimal health outcomes for modern humans. Evolution selected for reproductive success, not long-term disease prevention or lifespan extension. For example, humans evolved without toothpaste, but we still use it because it improves health outcomes beyond what’s “natural.” 

> Vegans often show up as healthier in studies than other groups, but correlation is not causation
>
> There’s the sniff test. A large percentage male vegan influencers look pale and sickly.

Methodological weaknesses in scientific research is challenging, but we need to be consistent. We cannot treat vegan nutrition science as uniquely unrealiable while accepting omnivore-leaning evidence uncritically.

So when we see a claim that “some male vegan influencers look pale and unhealthy,” this is not scientific evidence. The argument that vegan influencers look pale and sickly suffers from methodological errors e.g. there is a small sample size, anecdotes do not generalise, there is selection bias since influencers are not represtative of the average vegan, and there is no control group ie no comparison to omnivores under identical conditions. "Looking sickly" is subjective and influenced by lighting, makeup, or editing.

There can be issues with a vegan diet not getting complete protein (that is, low on one or more essential amino acids)

The issue of certain plant proteins not containing high levels of certain amino acids is not a problem if one eats a variety of plant proteins.