@ambiguous_yelp @anemone @SlicerDicer @barrett @sun right in the the abstract it says that "Vegans need reliable sources of vitamin B-12, such as fortified foods or supplements." so it sounds to me like you can't just "eat plants", but now you need to add vitamins/supplements because your food is not wholesome enough.

Just because the nutrient is in the plant doesn't mean it's bioavailable.