Cobalamin (Vitamin B-12) (B12)

Vitamin B-12, also known as cobalamin, is a complex water-soluble vitamin essential for DNA synthesis, methylation, and mitochondrial energy production (NIH Office of Dietary Supplements, 2023). It functions as a vital cofactor for two enzymes: methionine synthase, which converts homocysteine to methionine for protein synthesis and DNA methylation, and methylmalonyl-CoA mutase, which is involved in the catabolism of branched-chain amino acids and odd-chain fatty acids (StatPearls, 2023). Structurally, it is unique for containing a cobalt ion within a corrin ring, making it the most chemically complex of all vitamins (PubChem, 2024). Deficiency of Vitamin B-12 is a significant clinical concern, often resulting from malabsorption (e.g., pernicious anemia) or dietary insufficiency, leading to megaloblastic anemia and irreversible neurological damage (Mayo Clinic, 2023). In therapeutic contexts, Vitamin B-12 is administered as cyanocobalamin or hydroxocobalamin to restore levels and prevent hematological and neurological symptoms (StatPearls, 2023). Several medications, including metformin and proton pump inhibitors, are known to interfere with its absorption, necessitating monitoring in long-term users (American Family Physician, 2017).

Other names

CobalaminCyanocobalaminHydroxocobalaminMethylcobalaminAdenosylcobalaminExtrinsic factor

Acts as a cofactor for methionine synthase in the cytoplasm (converting homocysteine to methionine) and methylmalonyl-CoA mutase in the mitochondria (converting methylmalonyl-CoA to succinyl-CoA).