The vitamin B complex is a group of 12 substances that includes the eight vitamins known as

 

thiamine (vitamin B₁)

riboflavin (vitamin B₂)

niacin (vitamin B₃)

pantothenic acid (vitamin B₅)

pyridoxine (vitamin B₆)

biotin (vitamin B₇)

folic acid (vitamin B₉)

cyanocobalamin (also known as cobalamin or vitamin B₁₂)

 

These eight vitamins, like vitamin C, are soluble in water. (In contrast, vitamins A, D, E, and F are fat-soluble.) The B vitamins were once thought to be a single vitamin – vitamin B. Although now known to be chemically distinct they do tend to occur together in the same foodstuffs and are also related in that they all play important roles in cell metabolism.

 

Other substances making up the vitamin B complex, although not classified as vitamins, are chemically related to the eight types of B vitamin listed above. These include

 

choline

inositol

para-aminobenzoic acid (PABA)