Vitamin B-12 (cyanocobalamin) is a water soluble vitamin necessary for the maintenance of a healthy nervous system and for the production of energy from fats and proteins.* Vitamin B-12 is also essential for the synthesis of DNA during cell division and therefore is especially important for rapidly multiplying cells, such as blood cells.* In addition, adequate intake of vitamin B-12, along with folic acid and vitamin B-6, is critical for the conversion of homocysteine to methionine, thereby supporting a healthy cardiovascular system.* While B-12 is stored in the liver, dietary sources are of animal origin only (meat and dairy). Therefore, supplementation with B-12 may be especially important for strict vegetarians.
From the FDA's website: "As part of a well-balanced diet that is low in saturated fat and cholesterol, Vitamin B-12 may reduce the risk of vascular disease. FDA evaluated the above claim and found that, while it is known that diets low in saturated fat and cholesterol reduce the risk of heart disease and other vascular diseases, the evidence in support of the above claim is inconclusive."