A B complex vitamin usually delivers eight of the B vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), and B12 (cobalamin). Found naturally in meat, leafy greens, dairy, beans, peas, and whole or fortified grains...