Vitamin
hideA vitamin is an organic compound required as a nutrient in tiny amounts by an organism. A compound 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 the particular organism. For example, ascorbic acid functions as vitamin C for some animals but not others, and vitamins D and K are required in the human diet only in certain circumstances. The term vitamin does not include other essential nutrients such as dietary minerals, essential fatty acids, or essential amino acids, nor does it encompass the large number of other nutrients that promote health but are otherwise required less often.
Vitamins are classified by their biological and chemical activity, not their structure. Thus, each "vitamin" may refer to several vitamer compounds that all show the biological activity associated with a particular vitamin. Such a set of chemicals are grouped under an alphabetized vitamin "generic descriptor" title, such as "vitamin A," which includes the compounds retinal, retinol, and many carotenoids. Vitamers are often inter-converted in the body.
Vitamins have diverse biochemical functions, including function as hormones (e.g. vitamin D), antioxidants (e.g. vitamin E), and mediators of cell signaling and regulators of cell and tissue growth and differentiation (e.g. vitamin A). The largest number of vitamins (e.g. B complex vitamins) function as precursors for enzyme cofactor bio-molecules (coenzymes), that help act as catalysts and substrates in metabolism. When acting as part of a catalyst, vitamins are bound to enzymes and are called prosthetic groups. For example, biotin is part of enzymes involved in making fatty acids. Vitamins also act as coenzymes to carry chemical groups between enzymes. For example, folic acid carries various forms of carbon group – methyl, formyl and methylene - in the cell. Although these roles in assisting enzyme reactions are vitamins' best-known function, the other vitamin functions are equally important.
Until the 1900s, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) can alter the types and amounts of vitamins ingested. Vitamins have been produced as commodity chemicals and made widely available as inexpensive pills for several decades, allowing supplementation of the dietary intake.
For more information about Vitamin, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with vitamin
Citrus surprise: Vitamin C boosts the reprogramming of adult cells into stem cells
Dec 24, 2009 |
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Famous for its antioxidant properties and role in tissue repair, vitamin C is touted as beneficial for illnesses ranging from the common cold to cancer and perhaps even for slowing the aging process. Now, ...
More effort needed to crack down on 'secret remedies'
Dec 17, 2009 |
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The medical establishment and politicians must do more to crack down on alternative medicine, argues a senior scientist on BMJ.com today.
The changing pattern of childhood blindness in developing countries
Dec 08, 2009 |
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"Changing patterns of global childhood blindness suggest a reassessment of research, training, and programmatic needs," says a team of eye specialists from India, Malawi, and Tanzania.
Vitamin D levels associated with survival in lymphoma patients
Dec 05, 2009 |
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A new study has found that the amount of vitamin D in patients being treated for diffuse large B-cell lymphoma was strongly associated with cancer progression and overall survival. The results will be presented at the annual ...
Vitamin E extract could help tackle cancer tumours
Dec 03, 2009 |
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(PhysOrg.com) -- An extract of vitamin E could have a key role to play in the treatment of cancerous tumours, according to newly-published research today.
Heart failure linked to gene variant affecting vitamin D activation
Dec 01, 2009 |
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Previous studies have shown a link between low vitamin D status and heart disease. Now a new study shows that patients with high blood pressure who possess a gene variant that affects an enzyme critical to normal vitamin ...
Physicians Explore Link Between Vitamin D Deficiency and Hypertension
Nov 25, 2009 |
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(PhysOrg.com) -- Drs. William White and Pooja Luthra at the University of Connecticut Health Center are investigating a possible link between vitamin D deficiency and high blood pressure.
Autism treatment: Risky alternative therapies have little basis in science
Nov 24, 2009 |
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James Coman's son has an unusual skill. The 7-year-old, his father says, can swallow six pills at once. Diagnosed with autism as a toddler, the Chicago boy had been placed on an intense regimen of supplements and medications ...
Multiple health concerns surface as winter, vitamin D deficiences arrive
Nov 23, 2009 |
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A string of recent discoveries about the multiple health benefits of vitamin D has renewed interest in this multi-purpose nutrient, increased awareness of the huge numbers of people who are deficient in it, spurred research ...
Vitamin B niacin offers no extra benefit to statin therapy in seniors already diagnosed with CAD
Nov 18, 2009 |
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The routine prescription of extended-release niacin, a B vitamin (1,500 milligrams daily), in combination with traditional cholesterol-lowering therapy offers no extra benefit in correcting arterial narrowing and diminishing ...
Treatment with folic acid, vitamin B12 associated with increased risk of cancer, death
Nov 17, 2009 |
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Patients with heart disease in Norway, a country with no fortification of foods with folic acid, had an associated increased risk of cancer and death from any cause if they had received treatment with folic acid and vitamin ...
Genetic link to vitamin A deficiency
Nov 17, 2009 |
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(PhysOrg.com) -- Almost half of UK women may be lacking an important source of vitamin A due to a previously undiscovered genetic variation, scientists at Newcastle University have found.
Early end to key study on benefits of niacin, a B vitamin, in keeping arteries open was premature
Nov 16, 2009 |
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Heart experts at Johns Hopkins are calling premature the early halt of a study by researchers at Walter Reed Army Medical Center and Washington Hospital Center on the benefits of combining extended-release niacin, a B vitamin, ...
New study links vitamin D deficiency to cardiovascular disease and death
Nov 16, 2009 |
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While mothers have known that feeding their kids milk builds strong bones, a new study by researchers at the Heart Institute at Intermountain Medical Center in Salt Lake City suggests that Vitamin D contributes to a strong ...
Heart and bone damage from low vitamin D tied to declines in sex hormones
Nov 15, 2009 |
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Researchers at Johns Hopkins are reporting what is believed to be the first conclusive evidence in men that the long-term ill effects of vitamin D deficiency are amplified by lower levels of the key sex hormone estrogen, ...
