Definition of Selenium

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Selenium: An essential trace mineral that functions largely in the form of proteins, called selenoproteins, which act as enzymes and help prevent damage to cells in the body by oxidants in the environment or those produced by normal metabolism.

The recommended dietary allowance (RDA) is currently 55 micrograms of selenium per day for adult men and women, 60 micrograms per day for women during pregnancy and 70 micrograms per day for women during lactation. Food sources of selenium include seafood; some meats (such as kidney and liver); and some grains and seeds.

Too much selenium (selenosis) may cause reversible balding and brittle nails, give a garlic odor to the breath, and cause intestinal distress, weakness and slowed mental functioning.

Deficiency of selenium causes Keshan disease, a fatal form of cardiomyopathy (heart muscle disease).

See also: Selenocysteine; Selenoprotein.