Vitamin B-12 is a water soluble vitamin necessary for the maintenance of a healthy nervous system and for the metabolic utilization of 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 additioin, adequate intake of Vitamin B-12, along with Folic Acid and Vitamin B-6, encourages healthy serum homocysteine levels, thereby supporting cardiovascular health. Because Vitamin B-12 is found predominantly in animal products, strict vegetarians are at risk of developing Vitamin B-12 deficiency and may benefit from supplementation.

Vitamin B-12 is an especially important vitamin for maintaining healthy nerve cells, and it aids in the production of DNA and RNA, the body's genetic material. Vitamin B-12 also works closely together with vitamin B-9 (folate) to regulate the formation of red blood cells and to help iron function better in the body. The synthesis of S-adenosylmethionine (SAMe), a compound involved in immune function and mood, depends on the participation of folate and vitamin B-12.

Similar to other B complex vitamins, cobalamine is considered an "anti-stress" vitamin because it is believed to enhance the activity of the immune system and improve the body's ability to withstand stressful conditions.

Vitamins B-12, B-6, and B-9 (folate) work closely together to control blood levels of the amino acid homocysteine. Elevated levels of this substance appear to be linked with heart disease and, possibly, depression and Alzheimer's disease.

From the FDA's website: "As part of a well-balanced diet that is low in saturated fat and cholesterol, Vitamin B12 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."