- Vitamin D
- A steroid vitamin which promotes the intestinal absorption and metabolism of calcium and phosphorus. Under normal conditions of sunlight exposure, no dietary supplementation is necessary because sunlight promotes adequate vitamin D synthesis in the skin. Deficiency can lead to bone deformity (rickets) in children and bone weakness (osteomalacia) in adults. Vitamin D comes from the diet (eggs, fish, and dairy products) and is produced in the skin. Skin production of the active form of vitamin D depends 0n exposure to sunlight. Active people living in sunny regions produce most of the vitamin D they need from their skin. In less sunny climes the skin production of vitamin D is markedly diminished in the winter months, especially among the elderly and the housebound. In that population, vitamin D supplements become important. Vitamin D deficiency among the elderly is quite common in the US. In a study of hospitalized patients in a general medical ward, vitamin D deficiency was detected in 57% of the patients. An estimated 50% of elderly women consume far less vitamin D in their diet than recommended. The Food and Nutrition Board of the Institute of Medicine recommended the following as an adequate vitamin D intake: 200 IU daily for people 19-50 years old; 400 IU daily for those 51-70 years old; and 600 IU daily for those 71 years and older. An average multivitamin tablet contains 400 IU of vitamin D. Therefore, taking a multivitamin a day should help provide the recommended amount of vitamin D.
* * *vitamin D n any or all of several fat-soluble vitamins chemically related to steroids, essential for normal bone and tooth structure, and found esp. in fish-liver oils, egg yolk, and milk or produced by activation (as by ultraviolet irradiation) of sterols: asa) CALCIFEROLb) CHOLECALCIFEROL called also sunshine vitamin
* * *a fat-soluble vitamin that enhances the absorption of calcium and phosphorus from the intestine and promotes their deposition in the bone. It occurs in two forms: ergocalciferol (vitamin D2, calciferol), which is manufactured by plants when the sterol ergosterol is exposed to ultraviolet light, and cholecalciferol (vitamin D3), which is produced by the action of sunlight on 7-dehydrocholesterol, a sterol widely distributed in the skin. A deficiency of vitamin D, either from a poor diet or lack of sunlight, leads to decalcified bones and the development of rickets and osteomalacia. Good sources of vitamin D are liver and fish oils. The recommended daily intake is 10 µg for a child up to five years and 2.5 µg thereafter. Vitamin D is toxic and large doses must therefore be avoided.
* * *either of two fat-soluble compounds with antirachitic activity, or both collectively: cholecalciferol (q.v.), which is synthesized in the skin and is considered a hormone, and ergocalciferol (q.v.), which is the form generally used as a dietary supplement. Dietary sources include some fish liver oils, egg yolks, and fortified dairy products. Deficiency of vitamin D can result in rickets in children and osteomalacia in adults, while ingestion of excess levels can lead to hypercalcemia, mobilization of calcium from bone, and renal dysfunction. References to metabolites of vitamin D may denote those of cholecalciferol, of ergocalciferol, or of both collectively.
Medical dictionary. 2011.
Look at other dictionaries:
Vitamin K — has also been used as a slang term for ketamine, an unrelated anaesthetic. Vitamin K1 (phylloquinone). Both forms of the vitamin contain a functional naphthoquinone ring and an aliphatic side chain. Phylloquinone has a phytyl side chain … Wikipedia
Vitamin D — is a group of fat soluble prohormones, the two major forms of which are vitamin D2 (or ergocalciferol) and vitamin D3 (or cholecalciferol).cite web|url=http://dietary supplements.info.nih.gov/factsheets/vitamind.asp|title=Dietary Supplement Fact… … Wikipedia
Vitamin A — Systematic (IUPAC) name (2E,4E,6E,8E) 3,7 Dimethyl … Wikipedia
Vitamin B6 — is a water soluble vitamin. Pyridoxal phosphate (PLP) is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation. PLP also is necessary for the enzymatic reaction… … Wikipedia
Vitamin-B — ist eine Vitamin Gruppe, in der acht wasserlösliche Vitamine zusammengefasst sind, die alle als Vorstufen für Koenzyme dienen. Die Nummerierung ist nicht durchgehend, weil sich bei vielen Substanzen, die ursprünglich als Vitamine galten, der… … Deutsch Wikipedia
Vitamin B — ist eine Vitamin Gruppe, in der acht Vitamine zusammengefasst sind, die alle als Vorstufen für Koenzyme dienen. Die Nummerierung ist nicht durchgehend, weil sich bei vielen Substanzen, die ursprünglich als Vitamine galten, der Vitamin Charakter… … Deutsch Wikipedia
vitamin K — n. a fat soluble vitamin, synthesized constantly by intestinal bacteria in mammals and occurring in certain green vegetables, fish meal, etc., that promotes blood clotting and is required for the synthesis of prothrombin by the liver: the two… … Universalium
Vitamin A — is retinol. Carotene compounds (found, for example, in egg yolk, butter and cream) are gradually converted by the body to vitamin A (retinol). A form of vitamin A called retinal is responsible for transmitting light sensation in the retina of the … Medical dictionary
Vitamin B1 — is thiamine. Vitamin B1 acts as a coenzyme in the metabolism of the body. Deficiency of thiamine leads to beriberi, a disease of the heart and nervous system. The word vitamin was coined in 1911 by the Warsaw born biochemist Casimir Funk (1884… … Medical dictionary
Vitamin de — Beschreibung Deutschlernerzeitschrift Verlag NP PRESS.DE Erstausgabe 2002 Erscheinungsweise … Deutsch Wikipedia
vitamin de — Beschreibung Zeitschrift für junge Deutschlerner Verlag Verein vitamin de , NP PRESS.DE Erstausgabe 2002 … Deutsch Wikipedia