Vitamin B-12, also called cobalamin, is a water soluble vitamin that plays a key role in the formation of blood (red blood cells and white blood cells), normal functioning of the brain and nervous system. Vitamin B-12 is one of the eight B vitamins, and it is involved in the metabolism of every cell in the human body.Vitamin B-12 functions as a cofactor for methionine synthesis and L-methylmalonyl-CoA mutase. Vitamin B-12 is bound to protein in food, commonly found in fish, shellfish, meat, eggs and dairy products. The Vitamin B-12 is then released in the stomach by hydrochloric acid during digestion. Vitamin B-12 is then coupled with a component in the stomach called intrinsic factors (IF) before it is released and absorbed into the bloodstream at within the small intestine.