Humans vary in their ability to elongate fatty acids. It's possible that poor elongaters fail to thrive on a vegan diet and revert to a omnivorous diet, biasing

Humans vary in their ability to elongate fatty acids. It's possible that poor elongaters fail to thrive on a vegan diet and revert to a omnivorous diet, biasing the sample. We'd need a randomized controlled study to see if this is important.