Re: How do strict herbivore animals obtain vitamin B12?

Vitamin B12 is also known as Cobalamin. There's a very good web page with basic info on B12, including the statement that it comes only from animal matter -- which no doubt inspired this question.

I don't know the general answer to the question. I suspect it may vary from one animal to another. Certainly, what I can say is that herbivores obviously do get as much B12 as they need somehow. There are two possible ways this might come about:

1. The animals ingest it somehow. Some microorganisms (which are animals) produce B12, and these microorganisms can be found on vegetable matter that the animals eat. Yeast is an example of a B12-producing microorganism.
2. The animals have microorganisms in their gut that produce the B12 they need. Humans may have such bacteria in their stomach and/or intestine, and that may be why B12 deficiency is uncommon in humans.

Admin note: In fact, all vitamin B12 is microbially synthesized. Ruminants obtain it from the bacteria living in their specialized stomachs. The vitamin contains the element cobalt. If animals are deprived of trace amounts of cobalt, they are unable to obtain cobalamin from the bacteria, and so develop B12 deficiency. In humans, B12 deficiency is most commonly secondary to problems with absorption of the vitamin from the gut.

-L. Bry, MadSci Admin

McDonald P. Suttle NF., Abnormal fermentations in continuous cultures of rumen micro-organisms given cobalt-deficient hay or barley as the food substrate. British Journal of Nutrition. 56:369-78, 1986.