Adenosyl-Cobalamin B12 Assist contains 3000 mcg of vitamin B12 in its adenosylcobalamin form. Adenosylcobalamin is considered an active coenzyme form of B12, meaning it is used directly in B12-dependent enzyme reactions in the body. Vitamin B12 is required for red blood cell formation, neurological function, and DNA synthesis. Vitamin B12 also functions as a cofactor for methionine synthase and L-methylmalonyl-CoA mutase. Methionine synthase catalyzes the conversion of homocysteine to methionine. Methionine is required for the formation of SAMe (S-adenosylmethionine), which is the body’s most important methyl donor.