Selenium is a nonmetallic element with an atomic number of 34 and an atomic weight of 78.96. 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.
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 calcium, neither 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. In 1989, selenium 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 phosphorus, or 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 and theoretical applications in nutrition and internal 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) diets, because of its role in tissue repair and maintaining the youthful elasticity of skin.
Rebecca J. Frey PhD, The Gale Group Inc., Gale, Detroit,