Description
Vitamin B12 is a water-soluble vitamin needed for normal nerve cell activity, DNA replication, and production of the mood-affecting substance SAMe (S-adenosyl-Lmethionine). Vitamin B12 acts with folic acid and vitamin B6 to control homocysteine levels. Absorption of vitamin B12 is reduced with increasing age. Some research suggests that elderly people may benefit from 10 to 25 mcg per day of vitamin B12. One study of elderly people with vitamin B12 deficiency suggested that as much as 500 to 1,000 mcg of vitamin B12 per day might be necessary to achieve optimal vitamin B12 status. Vitamin B12 status was measured in this study using a sensitive laboratory test (the plasma methylmalonic acid concentration).