Vitamins are a group of organic nutrients required in small quantities for a variety of biological functions which cannot be synthesized in the body. In general, vitamins are classified into thirteen groups in human. Deficiency of some vitamins causes a specific disease. For example, beriberi is caused by a lack of vitamin B1. The disease is cured by restoring the vitamin to one’s diet. Vitamins are also classified as either water-soluble or fat-soluble vitamins. There are 9 water-soluble vitamins: vitamin B1 (thiamine), vitamin B2 (riboflavine), niacin, pantothenic acid, vitamin B6 (pyridoxine etc.), biotin, folic acid, vitamin B12 (cyanocobalamin), and vitamin C (ascorbic acid). The fat-soluble vitamins comprise vitamins A (retinol etc.), D (calciferols etc.), E (tocoferols etc.), and K (phylloquinone etc.). The followings are vitamins, vitamin related compounds, and vitamin derivatives that can be obtained from TCI.
W. Friedrich, in Vitamins, Walter de Gruyter, Berlin, 1988.