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Selenium Description Selenium is a nonmetallic element with an atomic number of 34 and an atomic weight of Its chemical symbol is Se. Selenium is most commonly found in nature in its inorganic form, sodium selenite.
An organic form of selenium, selenomethionine, is found in foods. General use The role of selenium in human nutrition and other therapeutic applications has provoked intense controversy over the past two decades. In contrast to such major minerals as magnesium and calciumneither selenium's benefits nor its toxic aspects are yet fully understood.
Until very recently, selenium was considered a toxic element that was not necessary to human health. Inselenium was reclassified as an essential micronutrient in a balanced human diet when the National Research Council established the first recommended daily allowance RDA for it.
It is considered a minor mineral, or a trace element, as distinct from a major mineral such as calcium or phosphorusor an electrolyte such as sodium or chloride.
There is less than 1 mg of selenium in the average human body. The selenium is concentrated in the liver, kidneys, and pancreas.
In males, selenium is also found in the testes and seminal vesicles. Selenium currently has a variety of applications, ranging from standard external preparations for skin problems to experimental Bethesda mining zirconium theoretical applications in nutrition and internal medicine.
Alternative medicine Naturopaths use selenium supplements to treat asthma, acne, tendinitis, infertility problems in men, and postmenopausal disorders in women. Selenium is also considered an important component in naturopathic life extension longevity dietsbecause of its role in tissue repair and maintaining the youthful elasticity of skin.
Dermatology Selenium has been used since the s in dandruff shampoos and topical medications for such skin disorders as folliculitis "hot tub" syndrome and tinea versicolor, a mild infection of the skin caused by the yeast-like fungus Pityrosporum orbiculare.
When selenium is compounded with sulfur to form a sulfide, it has antibiotic and antifungal properties. Selenium sulfide is absorbed by the outermost layer of skin cells, the epithelium. Inside the cells, the compound splits into selenium and sulfide ions.
The selenium ions counteract the enzymes that are responsible for producing new epithelial cells, thus lowering the turnover of surface skin cells. As a result, itching and flaking of the skin associated with dandruff and tinea versicolor is reduced.
Nutrition Prior tothere were no established RDA values for selenium. Males aged 15—18 years, 50 g; 19—24 years, 70 g; 25—50 years, 70 g; 51 years and older, 70 g. The generally higher levels for males are related to the importance of selenium in producing vigorous sperm.
The amount of selenium in the diet is influenced by its level in the soil. Most selenium is absorbed from food products, whether plants grown in the soil or animals that have eaten the plants.
Much of the selenium in foods is lost during processing. Selenium leaves the body in the urine and feces; males also lose some selenium through ejaculation of sperm. Selenium levels in soil vary widely, not only in different countries but also across different regions.
For example, in the United States the western states have higher levels of selenium in the soil than the eastern states. South Dakota has the highest rates of soil selenium in the United Stateswhile Ohio has the lowest.
Foods that are high in selenium contain the element in an organic form, selenomethionine. This form of selenium is considerably less toxic than inorganic sodium selenite or elemental selenium.
Good sources of selenium include brewer's yeast, wheat germwheat bran, kelp seaweedshellfish, Brazil nuts, barley, and oats. Onions, garlicmushrooms, broccoli, and Swiss chard may contain high amounts of selenium if they are grown in selenium-rich soil.
Selenium is also present in drinking water in some parts of the world and can be added to drinking water as a health measure. Nursing mothers should note that human milk is much richer in selenium than cow's milk.
There is no widely recognized deficiency syndrome for selenium, unlike the syndromes associated with calcium or magnesium hypocalcemia and hypomagnesemia, respectively. However, many researchers who have investigated Keshan disease, a form of heart disease in children, believe that it is caused by selenium deficiency.
The disease can be prevented but not cured with supplemental selenium; it responds to treatment with 50 g per day. The symptoms of Keshan disease, which is named for the region of China where it was discovered, include enlargement of the heart and congestive heart failure.
The soil in the Keshan region is low in selenium.
The researchers observed that the local Chinese treat Keshan disease with astragalus Astragalus membranaceusa plant that absorbs selenium from the soil.Ohio Mesothelioma Lawyers We are proud to represent mesothelioma victims and their families across the United States, including hardworking men and women in Ohio.
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