The term "B complex" refers to the group of B vitamins. It comprises vitamin B1 (thiamine), vitamin B2 (riboflavin), niacin (vitamin B3), pantothenic acid (vitamin B5), vitamin B6 (pyridoxine), biotin (vitamin B7 - vitamin H), folic acid (vitamin B9) and vitamin B12 (cobalamin). All B vitamins are water-soluble. Foods that are especially rich in B vitamins include whole-grain products, meat, offal, milk and dairy products.