What is vitamin?

  • (noun): Any of a group of organic substances essential in small quantities to normal metabolism.

Vitamin

A vitamin ( /ˈvaɪtəmɪn/ or /ˈvɪtəmɪn/) is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound (or related set of compounds) is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on the circumstances and on the particular organism. For example, ascorbic acid (vitamin C) is a vitamin for humans, but not for most other animals, and biotin and vitamin D are required in the human diet only in certain circumstances. By convention, the term vitamin does not include other essential nutrients such as dietary minerals, essential fatty acids, or essential amino acids (which are needed in larger amounts than vitamins), nor does it encompass the large number of other nutrients that promote health but are otherwise required less often. Thirteen vitamins are universally recognized at present.

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Some articles on vitamin:

Lumisterol
... Lumisterol is a compound that is part of the vitamin D family of steroid compounds ... stereoisomer of ergosterol and was produced as a photochemical by-product in the preparation of vitamin D1, which was a mixture of vitamin D2 and lumisterol ... Vitamin D2 can be formed from lumisterol by a electrocyclic ring opening and subsequent sigmatropic hydride shift ...
Calcitriol Receptor
... The calcitriol receptor, also known as the vitamin D receptor (VDR) and also known as NR1I1 (nuclear receptor subfamily 1, group I, member 1), is a member of the nuclear receptor family of transcription factors ... Upon activation by vitamin D, the VDR forms a heterodimer with the retinoid-X receptor and binds to hormone response elements on DNA resulting in expression or transrepression of specific geneproducts ... In humans, the vitamin D receptor is encoded by the VDR gene ...
Vitamin - Anti-vitamins
... Anti-vitamins are chemical compounds that inhibit the absorption or actions of vitamins ... Pyrithiamine is similar to thiamine, vitamin B1, and inhibits the enzymes that use thiamine ...
Alan Clemetson - Medical Hypotheses
... conducted and published the first studies concerning ascorbic acid (vitamin C) metabolism and depletion in pre-eclampsia ... The mechanism he argued to be high histamine levels associated with low serum vitamin C, the latter deficiency arising before birth due to factors such as the pregnant mother's malnutrition ... in Infants and Elevated Blood Histamine Caused by Vaccinations and Vitamin C Deficiency May Mimic the Shaken Baby Syndrome ...
Alcohol Consumption - Effects of Alcohol On Health - Alcoholism
... in alcoholism due to deficiency of folate, riboflavin, vitamin B6, and selenium this can lead to Korsakoff's syndrome ... which is caused by a deficiency in thiamine (vitamin B1) ... fractures may occur due to deficiency of vitamin D ...