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Vitamin B12, or cyanocobalamin, is a group of cobalt-containing water-soluble vitamins. They are coenzymes necessary for red blood cell production - folate polyglutamate is the major red cell form of folate. It is crucial for neurologic function and DNA synthesis.
Vitamin B12 is derived primarily from food of animal origin, including dairy products.
Absorption of B12 from the gastrointestinal tract is dependent on acid and intrinsic factor secreted by the stomach’s parietal cells.
The recommended dietary allowance (RDAs) for vitamin b12 in the adult is 2.4 micrograms (2). A normal liver stores about 3 mg which is sufficient for several years.