Vitamin B12 functions as a coenzyme in two forms, adenosylcobalamin and methylcobalamin. Adenosylcobalamin is used by the enzyme methylmalonyl-CoA mutase to convert methylmalonyl-CoA to succinyl-CoA during fatty acid breakdown. Methylcobalamin is used by the enzyme methionine synthase to convert homocysteine to methionine, which provides methyl groups for many biological processes. Vitamin B12 deficiency can cause neurological abnormalities due to the accumulation of abnormal fatty acids and reductions in methionine and S-adenosylmethionine. Cyanocobalamin can also detox