B12, like other B vitamins, is a water-soluble vitamin. Mega B12 functions as a co-enzyme and is involved in the synthesis of the essential amino acid methionine. In the body, Vitamin B12 is used in the regulation and formation of red blood cells and helps in the utilization of iron. It has also been shown to assist in lowering homocysteine levels. It helps convert carbohydrates into fat and must be available in the system as it is involved in the formation of red blood cells. Deficiency is usually due to a problem in absorption rather than from diet. Vitamin B12 is absent from most fruits, vegetables and grains. Vegetarians are more susceptible to deficiency. This is caused by a lack of intrinsic factors, a substance secreted by the stomach.