Not if they actually do their research and SUPPLEMENT properly. It cannot reliably be done naturally. It is difficult to get B12 from vegan sources. Most will argue that they can get B12 from fortified foods, but fortified means added artificially.
Many "vegans", unfortunately, are not actually aware of what is in their food. I have had them aghast at the suggestion that bread might contain milk and/or eggs (Apparently it's not common knowledge that those are common ingredients in bread). I've also seen "vegans" eat jello. Many "vegans" are, in reality, just really whiny vegetarians.
Caption this Meme
