|Dictionary, Encyclopedia and Thesaurus - The Free Dictionary|
6,831,900,583 visitors served.
|Also found in: Dictionary/thesaurus, Encyclopedia, Wikipedia||0.01 sec.|
Vitamins are organic components in food that are needed in very small amounts for growth and for maintaining good health. The vitamins include vitamin D, vitamin E, vitamin A, and vitamin K, or the fat-soluble vitamins, and folate (folic acid), vitamin B12, biotin, vitamin B6, niacin, thiamin, riboflavin, pantothenic acid, and vitamin C (ascorbic acid), or the water-soluble vitamins. Vitamins are required in the diet in only tiny amounts, in contrast to the energy components of the diet. The energy components of the diet are sugars, starches, fats, and oils, and these occur in relatively large amounts in the diet.
Most of the vitamins are closely associated with a corresponding vitamin deficiency disease. Vitamin D deficiency leads to diseases of the bones such as osteoporosis and rickets. Vitamin E deficiency occurs only rarely, and causes nerve damage. Vitamin A deficiency is common throughout the poorer parts of the world, and causes night blindness. Severe vitamin A deficiency can result in xerophthalamia, a disease which, if left untreated, results in total blindness. Vitamin K deficiency results in spontaneous bleeding. Mild or moderate folate deficiency is common throughout the world, and can result from the failure to eat green, leafy vegetables or fruits and fruit juices. Folate deficiency causes megaloblastic anemia, which is characterized by the presence of large abnormal cells called megaloblasts in the circulating blood. The symptoms of megaloblastic anemia are tiredness and weakness. Vitamin B12 deficiency occurs with the failure to consume meat, milk or other dairy products. Vitamin B12 deficiency causes megaloblastic anemia and, if severe enough, can result in irreversible nerve damage. Niacin deficiency results in pellagra. Pellagra involves skin rashes and scabs, diarrhea, and mental depression. Thiamin deficiency results in beriberi, a disease that can cause atrophy, weakness of the legs, nerve damage, and heart failure. Vitamin C deficiency results in scurvy, a disease that involves bleeding. Specific diseases uniquely associated with deficiencies in vitamin B6, riboflavin, or pantothenic acid have not been found in humans, though persons who have been starving, or consuming poor diets for several months, might be expected to be deficient in most of the nutrients, including vitamin B6, riboflavin, and pantothenic acid.
Some of the vitamins serve only one function in the body, while other vitamins serve a variety of unrelated functions. Therefore, some vitamin deficiencies tend to result in one type of defect, while other deficiencies result in a variety of problems.
People are treated with vitamins for three reasons. The primary reason is to relieve a vitamin deficiency, when one has been detected. Chemical tests suitable for the detection of all vitamin deficiencies are available. The diagnosis of vitamin deficiency often is aided by visual tests, such as the examination of blood cells with a microscope, the x-ray examination of bones, or a visual examination of the eyes or skin.
A second reason for vitamin treatment is to prevent the development of an expected deficiency. Here, vitamins are administered even with no test for possible deficiency. One example is vitamin K treatment of newborn infants to prevent bleeding. Food supplementation is another form of vitamin treatment. The vitamin D added to foods serves the purpose of preventing the deficiency from occurring in persons who may not be exposed much to sunlight and who fail to consume foods that are fortified with vitamin D, such as milk. Niacin supplementation prevents pellagra, a disease that occurs in people who rely heavily on corn as the main source of food, and who do not eat much meat or milk. In general, the American food supply is fortified with niacin.
A third reason for vitamin treatment is to reduce the risk for diseases that may occur even when vitamin deficiency cannot be detected by chemical tests. One example is folate deficiency. The risk for cardiovascular disease can be slightly reduced for a large fraction of the population by folic acid supplements. And the risk for certain birth defects can be sharply reduced if certain pregnant women use folic acid supplements.
Vitamin treatment is important during specific diseases where the body's normal processing of a vitamin is impaired. In these cases, high doses of the needed vitamin can force the body to process or utilize it in the normal manner. One example is pernicious anemia, a disease that tends to occur in middle age or old age, and impairs the absorption of vitamin B12. Surveys have revealed that about 0.1% of the general population, and 2-3% of the elderly, may have the disease. If left untreated, pernicous anemia leads to nervous system damage. The disease can easily be treated with large oral daily doses of vitamin B12 (hydroxocobalamin) or with monthly injections of the vitamin.
Vitamin supplements are widely available as over-the-counter products. But whether they work to prevent or curtail certain illnesses, particularly in people with a balanced diet, is a matter of debate and ongoing research. For example, vitamin C is not proven to prevent the common cold. Yet, millions of people take it for that reason. A physician or pharmacist can provide more information on the appropriate use of multivitamin supplements. Likewise, though vitamin supplements have been touted as a prevention for cancer, a 2004 report by the U.S. Preventive Services Task Force concluded that the evidence is inadequate to recommend supplementation of vitamins A, C, or E, multivitamins with folic acid, or antioxidant combinations to decrease the risk of cancer.
Vitamin A and vitamin D can be toxic in high doses. Side effects range from dizziness to kidney failure. A physician or pharmacist can help with the correct use of a multivitamin supplement that contains these vitamins.
Vitamin treatment usually is done in three ways: by replacing a poor diet with one that supplies the recommended dietary allowance, by consuming oral supplements, or by injections. Injections are useful for people with diseases that prevent absorption of fat-soluble vitamins. Oral vitamin supplements are especially useful for people who otherwise cannot or will not consume food that is a good vitamin source, such as meat, milk, or other dairy products. For example, a vegetarian who will not consume meat may be encouraged to consume oral supplements of vitamin B12.
Treatment of genetic diseases that impair the absorption or utilization of specific vitamins may require megadoses of the vitamin throughout one's lifetime. Megadose means a level of about 10-1,000 times greater than the recommended daily allowance (RDA). Pernicious anemia, homocystinuria, and biotinidase deficiency are three examples of genetic diseases that are treated with megadoses of vitamins.
The diagnosis of a vitamin deficiency usually involves a blood test. An overnight fast usually is recommended as preparation prior to withdrawal of the blood test so that vitamin-fortified foods do not affect the test results.
Response to vitamin treatment can be monitored by chemical tests, by an examination of red blood cells or white blood cells, or by physiological tests, depending on the exact vitamin deficiency.
Few risks are associated with supervised vitamin treatment. Risks depend on the vitamin and the reason why it was prescribed. Ask a physician or pharmacist about how and when to take vitamin supplements, particularly those that have not been prescribed by a physician.
"The Next Big Deficiency." Chain Drug Review February 16, 2004: 26.
Sadovsky, Richard. "Can Vitamins Prevent Cancer and Heart Disease?" American Family Physician February 1, 2004: 631.
Genetic disease — A genetic disease is a disease that is passed from one generation to the next, but does not necessarily appear in each generation. An example of genetic disease is Down's syndrome.
Plasma — Blood consists of red and white cells, as well as other components, that float in a liquid. This liquid is called plasma.
Recommended dietary allowance (RDA) — The Recommended Dietary Allowances (RDAs) are quantities of nutrients of the diet that are required to maintain human health. RDAs are established by the Food and Nutrition Board of the National Academy of Sciences and may be revised every few years. A separate RDA value exists for each nutrient. The RDA values refer to the amount of nutrient expected to maintain health in the greatest number of people.
Serum — Serum is blood plasma with the blood clotting proteins removed. Serum is prepared by removing blood from the subject, allowing the blood naturally to form a blood clot, and then using a centrifuge to remove the red blood cells and the blood clot. The blood clot takes the form of an indistinct clump.
Vitamin status — Vitamin status refers to the state of vitamin sufficiency or deficiency of any person. For example, a test may reveal that a patient's folate status is sufficient, borderline, or severely inadequate.
vitamins organic substances that are necessary in the diet, in very small quantities, for normal growth and health: the recommended daily allowance (RDA) for any vitamin, widely quoted on food and drink labels, is less than 200 mg. Originally identified by alleviation of conditions caused by their deficiency (e.g. of scurvy in ships' crews in the 1750s by providing citrus fruit, the vital component being found later to be ascorbic acid, vitamin C). Nowadays hypovitaminosis due to lack of one or more vitamins is rare on a well-balanced diet, although occasionally an athlete may suffer from a deficiency, e.g. if dieting for weight loss or eliminating particular foods or food groups from the diet. hypervitaminosis can occur with excessive intake of one or more vitamins. The International Olympic Committee states that no vitamin supplements should be required if the diet is well balanced but athletes do often take them, especially vitamins C, B-complex and E, with a possible danger to their health by overconsumption. For sources, functions and deficiency effects, see Table 1.
Patient discussion about Vitamins.
Q. Should I take vitamins? I try to eat a healthy balanced diet everyday. Do I still need to take vitamins additionally?
A. Unless your Doctor told you that you suffer from a vitamin deficiency, then eating a healthy balanced diet is enough in order to get all the necessary vitamins. Make sure to eat fresh fruits and vegetables, which are rich with them. Also People who eat a vegetarian diet may need to take a vitamin B12 supplement.
Q. Are Vitamins really helpful? I realize that there's an entire industry around it but I was wondering how helpful vitamins really are. Is there a difference between vitamins from fruits and vegetables and vitamins that you buy off the shelve? Is there such a thing as taking too much vitamins?
A. Yes, vitamins are helpful. I recently stopped taking my supplement to see if I felt a difference. Once I stopped taking it my anxiety attacks returned and my energy level went down. Nutrition that we get from food is the best, but the truth is that we don't get the amount of nutrition that we need daily. Yes, it is a such thing as taking too many vitamins. This is why it is still good consult with your doctor when taking any kind of vitamin or supplement. When chosing a vitamin for myself price is not a concern when it comes to health. This is why I prefer more expensive vitamins rather than over the counter.
Q. what vitamins are recommended for treating cold? and what is the right amount of it ?
A. Actually, although studied in trials, vitamins C, E and zinc wasn't found to have a substantial effect either preventing or relieving the symptoms of common cold, so currently these vitamins can't be recommended for the treatment of common cold.Read more or ask a question about Vitamins
You may read more here: http://www.nlm.nih.gov/medlineplus/commoncold.html
Want to thank TFD for its existence? Tell a friend about us, add a link to this page, or visit the webmaster's page for free fun content.
|Mentioned in||?||References in periodicals archive||?||Medical browser||?||Full browser||?|
ataxia with isolated vitamin E deficiency
B complex vitamins
Meyers, director of the Food and Nutrition Board, which sets the government's recommended daily intake values for all vitamins and some minerals, agrees that "it really is time to look at those [intake standards] again for vitamin D.
Early hype So how did vitamin C steal the spotlight from the other 12 vitamins essential to human health?
Vitamins are carbon-containing substances, necessary in minute amounts for normal metabolism.
Vitamin-B12 dependent methionine synthase
Vitaminic Music Club
VitaminsVitamins in Stroke Prevention
Vitamins Mineral Herbal Supplements
Vitamins, Minerals and Supplements
Vitasoy International Holdings Ltd.
Vitaui Lazarevich Ginzburg
Vitautas Algirdo Chekanauskas
Vitautas Iustino Bredikis
Vitautas Juliono Klova
Vitautas Prano Žalakjavcius
Free toolbar & extensions |
Word of the Day |
For webmasters: Free content | Linking | Lookup box | Double-click lookup