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
Heart and bone damage from low vitamin D tied to declines in sex hormones
6 hours ago |
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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. ...
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 ...
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 ...
Commentary warns of unexpected consequences of proton pump inhibitor use in reflux disease
Nov 03, 2009 |
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Despite being highly effective and beneficial for many patients, unexpected consequences are emerging in patients who are prescribed proton pump inhibitors (PPIs) for reflux diseases. Physicians are warned to monitor these ...
Low vitamin D levels explains most ESRD risk in African-Americans
Oct 29, 2009 |
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Low levels of vitamin D may account for nearly 60 percent of the elevated risk of end-stage renal disease (ESRD) in African Americans, according to a report in the December Journal of the American Society of Nephrology (J ...
Weekly and biweekly vitamin D2 prevents vitamin D deficiency
Oct 26, 2009 |
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Boston University School of Medicine researchers (BUSM) have found that 50,000 International Units (IU) of vitamin D2, given weekly for eight weeks, effectively treats vitamin D deficiency. Vitamin D2 is a mainstay for the ...
Latest analysis confirms suboptimal vitamin D levels in millions of US children
Oct 26, 2009 |
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Millions of children in the United States between the ages of 1 and 11 may suffer from suboptimal levels of vitamin D, according to a large nationally representative study published in the November issue of Pediatrics, accomp ...
Eating right, not supplements, is best at keeping your good bacteria healthy, dietitian says
Oct 21, 2009 |
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Healthy eating, not supplements, is the best way to keep the good bacteria in your gut healthy, says a dietitian and researcher.
Lowering blood pressure
Oct 16, 2009 |
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The words are in larger-than-average type. The message is simple: "The Blood Pressure Miracle." And Frank Mangano, health advocate and natural health writer, says that's all it takes to lower your blood pressure -- naturally.
Study supports possible role of urate in slowing Parkinson's disease progression
Oct 12, 2009 |
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By examining data from a 20-year-old clinical trial, a research team based at the MassGeneral Institute for Neurodegenerative Diseases (MGH-MIND) and Harvard School of Public Health (HSPH), has found evidence supporting the ...
Women with breast cancer have low vitamin D levels
Oct 09, 2009 |
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Women with breast cancer should be given high doses of vitamin D because a majority of them are likely to have low levels of vitamin D, which could contribute to decreased bone mass and greater risk of fractures, according ...
