 Vitamin, a vitamin is an organic molecule or related set of molecules which is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. The essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others. It is not a vitamin in the first instance but in the second. The term vitamin does not include the three other groups of essential nutrients, minerals, essential fatty acids, and essential amino acids. Most vitamins are not single molecules, but groups of related molecules called For example, vitamin B consists of four tocopherols and four toco-triannols. The thirteen vitamins required by human metabolism are Vitamin A retinols and carotenoids Vitamin B1-thitamin Vitamin B2-riboflavin Vitamin B3-niacin Vitamin B5-pandaphenic acid Vitamin B6-pyridoxine Vitamin B7-biotin Vitamin B9-polycacid Dortholate Vitamin B12-covalamins Vitamin CS-corbic acid Vitamin D-calciferols Vitamin D-tocopherols and toco-triannols and vitamin K-keynoteness Vitamins have diverse biochemical functions. Some forms of vitamin A function as regulators of cell and tissue. To growth and differentiation, the B-complex vitamins function as enzyme cofactors coenzymes for the precursors for them. Vitamin D has a hormone-like function as a regulator of mineral metabolism for bones and other organs. Vitamins C and E function as antioxidants. Both deficient and excess intake of a vitamin can potentially cause clinically significant illness, although excess intake of water-soluble vitamins is less likely to do so. Before 1935, the only source of vitamins was from food. If intake of vitamins was lacking, the result was vitamin deficiency and consequent deficiency diseases. Then, commercially produced tablets of yeast extract vitamin B-complex and semi-synthetic vitamin C became available. This was followed in the 1950s by the mass production and marketing of vitamin supplements, including multivitamins, to prevent vitamin deficiencies in the general population. Government's mandated addition of vitamins to staple foods such as flour or milk, referred to as food fortification, to prevent deficiencies. Recommendations for folic acid supplementation during pregnancy reduce risk of infant neural tube defects. Although reducing incidence of vitamin deficiencies clearly is benefits, supplementation is thought to be of little value for healthy people who are consuming a vitamin-adequate diet. The term vitamin is derived from the word vitamin, coined in 1912 by biochemist Cozimir Funk, who isolated a complex of micronutrients essential to life, all of which he presumed to be of means. When this presumption was later determined not to be true, the E was dropped from the name. All vitamins were discovered and identified between 1913 and 1948.