B12 and vegetarianism

The ability of a strict vegetarian diet to supply adequate amounts of B12 remains controversial, despite increasing evidence in support of vegetarianism and its nutritional adequacy. The controversy is fueled by two somewhat divergent schools of thought. One school emphasizes the fact that most animals, including humans, are capable of storing long-term supplies of B12.

In humans, these stores may last for twenty years or longer. Given this potential for storage, a daily requirement for B12 is regarded as highly unlikely.