[Eva]

It was B12, I did a little reading, but couldn't find the precise article. I did find some articles that claimed that the B12 deficiency was caused by an absorption problem caused by the vegetarian diet and could not be ameliorated by vitamin supplements.

[Lil'freeper]

the B12 deficiency was caused by an absorption problem caused by the vegetarian diet

Could be the same "bioavailability" debate I keep stumbling across. There are several vitamins that occur in animal tissues that have analogs in plants. Sometimes it's a problem of funky isomers that don't fit the same way into the human metabolism. Other times the plant molecule is a precursor to the desired molecule- requiring the body to work harder to get at the needed nutrient. Vitamin A and it's plant version (beta carotene) comes to mind.