The vitamin B12 form methylcobalamin is required as cofactor for the function of the vitamin B9 (folate)-dependent enzyme that catalyzes the synthesis of the amino acid methionine from homocysteine. Methionine in turn is required for the synthesis of a methyl (-CH3) group donor, used in many biological reactions to add a methyl group to another molecule (‘methylation’) such as DNA (2). Methylation of DNA may be important in cancer prevention.
The other form of vitamin B12, 5-deoxyadenosylcobalamin, is required as cofactor by an enzyme, which plays an important role in the production of energy from fats and proteins, and in the synthesis of haemoglobin, the oxygen carrying pigment in red blood cells (2).
The European Food Safety Authority (EFSA), which provides scientific advice to assist policy makers, has confirmed that clear health benefits have been established for the dietary intake of vitamin B12 in contributing to:
Authored by Dr Peter Engel in 2010, reviewed and revised by Angelika Friedel on 29.06.2017