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
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 ...
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 ...
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 ...
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, ...
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, ...
High fat diet increases inflammation in the mouse colon
Nov 12, 2009 |
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(PhysOrg.com) -- In mice fed a diet high in fat and low in fiber, vitamin D and calcium -- the so-called Western diet -- expression of a series of genes collectively associated with immune and inflammatory responses was altered. ...
UN says hunger stunts some 200 million children
Nov 11, 2009 |
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(AP) -- Nearly 200 million children in poor countries have stunted growth because they don't get enough to eat, according to a new report published by UNICEF Wednesday before a three-day international summit on the problem ...
Blood test identifies women at risk from Alzheimer's
Nov 06, 2009 |
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Middle-aged women with high levels of a specific amino acid in their blood are twice as likely to suffer from Alzheimer's many years later, reveals a thesis from the Sahlgrenska Academy at the University of Gothenburg, Sweden. ...
Children who often drink full-fat milk weigh less
Nov 03, 2009 |
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Eight-year-old children who drink full-fat milk every day have a lower BMI than those who seldom drink milk. This is not the case for children who often drink medium-fat or low-fat milk. This is one conclusion of a thesis ...
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.
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 ...
Eating, drinking and lifestyle changes can boost immunity to ward off seasonal flu
Nov 05, 2009 |
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College students looking to stay healthy during flu and exam season need to focus on three very important factors, says a nutritionist at Washington University in St. Louis.
Researchers explore new ways to prevent spinal cord damage using a vitamin B3 precursor
Nov 05, 2009 |
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Substances naturally produced by the human body may one day help prevent paralysis following a spinal cord injury, according to researchers at Weill Cornell Medical College. A recent $2.5 million grant from the New York State ...
