Vitamin B-12 is needed for normal nerve cell activity. Vitamin B-12 is also needed for DNA replication, and production of the mood-affecting substance called SAMe (S-adenosyl-L-methionine). Vitamin B-12 works with folic acid to control homocysteine levels. An excess of homocysteine, which is an amino acid (protein building block), may increase the risk of heart disease, stroke, and perhaps osteoporosis and Alzheimers disease. |