B12 (Adenosyl/Hydroxy) provides 2000 ug of vitamin B12 as a blend of ‘active’ forms. Adenosylcobalamin is an activated form of vitamin B12. Hydroxycobalamin is a precursor form of vitamin B12 that is converted in the body to both methylcobalamin and adenosylcobalamin. Adenosylcobalamin and hydroxycobalamin have independent and unique biological functions. Vitamin B12 contributes to normal functioning of the nervous system and psychological function. Vitamin B12 contributes to normal energy-yielding metabolism and the reduction of tiredness and fatigue.