There are 13 known vitamins, classified into two groups: water-soluble and fat-soluble vitamins.

Fat-soluble vitamins

A (retinol and its precursor b-carotene)
D (calciferol)
E (tocopherol)
K (phylloquinone)

Water-soluble vitamins

B1 (thiamin)
B2 (riboflavin)
B3 (niacin, nicotinic acid)
B5 (pantothenic acid)
B6 (pyridoxin)
B8 (biotin)
B9 (folate, folacin, folic acid)
B12 (cobalamin)
C (ascorbic acid)