Photovoltaic and photographic equipment use selenium for its chemical properties. The glass industry uses it for a pigment which imparts red color to glass and enamel. First identified in 1817 by Jons Jakob Berzeleus; selenium is named for the Greek word selene which means moon.

Selenium is used in the human body to form selenoproteins which are antioxidants. They are not like other antioxidants which are primarily polyphenols.

Although selenium can be obtained from some plants; the plants do not produce this substance as they do the vitamin antioxidants. The level of selenium present in plants varies according to the level in the soil where each plant is grown.

Rather selenium is a mineral which is absorbed by plants and made into other biological compounds. One of these substances, called selenomethionine is found in some staple foods of many global diets. Foods like corn, soybeans, and wheat contain selenomethionine.

Selenium is a trace element in the human diet meaning, of course, that only a small amount of it is needed. Too much of a good thing, is a truism which would apply to high amounts of this nutrient. Levels higher than the upper tolerable level (400 micrograms per day) would result in minor selenosis symptoms like alopecia--loss of hair. In cases of higher amounts of dietary supplementation, cirrhosis of the liver or pulmonary edema could result.

Selenium plays a role in thyroid function and its use may prevent goiters from developing. This is because of its iodine complement. Goiters are growths which occur on the thyroid located on the underside of the throat in the absence of dietary iodine. Selenium deficiency exacerbates this condition.

Keshan Disease(which causes enlarging of the heart); Kashin-Beck(causes osteoarthropathy) and Myxedematous Endemic Cretinism(which results in mental retardation) are all diseases known to be caused by selenium deficiency.

Aboriginal diets tend to be low in selenium in sub-Saharan Africa but high in part of Northern Nebraska and the Dakotas. Human Immunodeficiency Virus (HIV / AIDS) infections have been found in greater numbers in areas of Africa which have selenium poor soil than in Senegal which does not.

This has led researchers to study the possible correlation. It has been discovered that there is evidence of slow decline in selenium levels in individuals who suffer from this disease. Anyone with this disease may benefit from selenium supplementation.

Additionally, selenium may complement vitamin E to achieve a greater antioxidant effect. Selenium reduces cataract formation as one of its strong antioxidant roles. It is believed to prevent blood clots from forming near the site of blood vessel damage in the brain and heart.

Good dietary sources of selenium include some yeasts with 1,000 to 2,000 micrograms of selenium per gram. It occurs in bran, broccoli, garlic oatmeal onions, mushrooms and tuna as well as many other foods.

So it would seem that this mineral which is used industrially and made from a byproduct of copper smelting serves man in many health concerns as well.