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 DNA synthesis during cell division and, therefore, is especially important for rapidly multiplying cells, such as blood cells. In addition, the adequate intake of vitamin B-12, along with folic acid and vitamin B-6, promotes healthy levels of homocysteine in the serum, which promotes cardiovascular health.