A. B12-Active is the biologically active form of the dietary supplement vitamin B12, and is referred to as methylcobalamin. The production of methylcobalamin begins when cyanocobalamin is made via a natural fermentation process of bacteria. Cyanocobalamin is then modified to produce methylcobalamin.1 While dietary sources of vitamin B12 are almost exclusively animal products,2 methylcobalamin is commercially produced and is not isolated from an animal source.1

A. Active B12, methylcobalamin, is considered the most bioavailable form of vitamin B12. "Regular" B12, cyanocobalamin, is the most common form of vitamin B12. Cyanocobalamin must be converted to the active form (either methylcobalamin or adenosyl cobalamin) by the body.