Vitamin B12 (Cobalamin) (B12)

Vitamin B12—also known as cobalamin—is an essential water-soluble vitamin required for red blood cell production, neurological function including myelin sheath maintenance, DNA synthesis and repair, and homocysteine metabolism. It occurs naturally only in animal-derived foods but can be synthesized industrially via bacterial fermentation for use in supplements. Deficiency can result from inadequate dietary intake (e.g., vegan diets), impaired absorption due to lack of intrinsic factor or gastrointestinal disorders/surgery, certain medications that interfere with its uptake/metabolism, or inherited metabolic defects. Supplementation can be administered orally at high doses even when intrinsic factor is lacking because passive diffusion allows some uptake; parenteral administration bypasses the need for gastrointestinal absorption entirely. Clinical indications include treatment/prevention of megaloblastic/pernicious anemia and neuropathy caused by deficiency; it also serves as an antidote for cyanide poisoning when given as hydroxocobalamin.

Other names

CobalaminCyanocobalamin (synthetic supplement form)Hydroxocobalamin (injectable form)Methylcobalamin (active coenzyme form)

Supplementation restores normal levels of cobalamin in individuals who are deficient due to dietary insufficiency or malabsorption. It acts as a cofactor in enzymatic reactions involved in DNA synthesis and homocysteine metabolism; injectable forms bypass gastrointestinal absorption issues seen in pernicious anemia or after gastric surgery.