Methylcobalamin is an activated, highly bioavailable form of vitamin B12, which acts as the principal circulating form of cobalamin in the body. In general, vitamin B12 works with folate to promote red blood cell formation. Additionally, vitamin B12 is an important cofactor for energy metabolism. One vitamin B12-dependent enzyme is methylmalonyl-CoA mutase, which is involved in the formation of succinyl-CoA, a key Krebs cycle intermediate. Vitamin B12 is also a vital component of the methionine synthase pathway.