Methylcobalamin (an active form of vitamin B12) is essential for recycling homocysteine and the formation of methyl donors involved in cardiovascular function, sleep, blood cell formation, and nerve function.* Most vitamin B12 supplements contain cyanocobalamin; however, the liver must first "detoxify" the cyanide molecule and attach a methyl group to form methylcobalamin from the cyanocobalamin. Methylcobalamin is already in the biologically active, tissue-ready form.* Evidence indicates the body utilizes methylcobalamin more efficiently than it does cyanocobalamin.* Research shows the quantity of cobalamin detected following a small oral dose of methylcobalamin is similar to the amount following administration of cyanocobalamin; but significantly more cobalamin accumulates in liver tissue following administration of methylcobalamin. Human urinary excretion of methylcobalamin is about one-third that of a similar dose of cyanocobalamin, indicating substantially greater tissue retention.*