Vitamin B12, also known as cobalamine or cyanocobalamine, comprises a number of forms including cyano-, methyl-, deoxyadenosyl- and hydroxy-cobalamin. Vitamin B12 is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system via the synthesis of myelin (myelinogenesis), and the formation of red blood cells. It is one of eight B vitamins involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acid metabolism.