How do you become low in b12.

Pernicious anemia: In the usa the most common cause of B12 deficiency is pernicious anemia ( your stomach stops producing intrinsic factor necessary for absorption of B12 due to antibodies ). In finland there is an intestinal parasite then may dplete B12 ( diphilobotrium latum ). Very poor diet in elderly people is a second most common cause in usa.

Causes: It could be deficient in diet or not absorbing due to lack of intrinsic factor.