noun, plural: water-soluble vitamins
Vitamins are organic compounds that an organism need in trace but in sufficient amounts for normal growth and metabolic processes. Etymologically, the term vitamin is derived from vitamine, which is a word coined by Polish biochemist Kazimierz Funk.1
Vitamins are chemical compounds that are not synthesized in adequate amounts within the organism and therefore must be obtained through diet. There are two groups of vitamins that are classified according to solubility. They are (1) fat-soluble vitamins and (2) water-soluble vitamins. Fat-soluble vitamins, as the name implies, are vitamins that are soluble in fat solvents. In contrast, water-soluble vitamins are those that dissolve in water. Since they dissolve easily in water they are readily excreted from the body through urine. Unlike fat-soluble vitamins, the water-soluble vitamins are not stored in the body. In humans, there are 9 water-soluble vitamins, particularly the 8 B vitamins (i.e. thiamin, riboflavin, niacin, pyridoxine, folate, vitamin B12, biotin and pantothenic acid) and vitamin C.
1 Iłowiecki, Maciej (1981). Dzieje nauki polskiej. Warszawa: Wydawnictwo Interpress. p. 177.