


Vitamin B12 is an essential water-soluble vitamin that is commonly found in a variety of foods, such as fish, shellfish, meat, eggs, and dairy products. Vitamin B12 is frequently used in combination with other B vitamins in a vitamin B complex formulation. Vitamin B12 is important in DNA synthesis. Vitamin B12 is bound to the protein in food. Acid in the stomach releases B12 from protein during digestion. Once released, B12 combines with a substance called intrinsic factor (IF) before it is absorbed into the bloodstream.

The human body stores several years' worth of vitamin B12 in the liver, so low levels in the body are rare. Decreases in vitamin B12 levels are more common in the elderly, HIV-infected persons, and vegetarians. Inability to absorb vitamin B12 from the intestinal tract can cause a type of anemia called pernicious anemia. Fever and symptoms of "excessive sweating" have been reported with anemia due to low levels of vitamin B12; however, these are fixed with vitamin B12 treatment.
