During the past 20 years sellenium significance in our diet has rapidly grown. Sellenium protects body tissues against oxidative stress and maintain defences against infection. Sellenium content of normal adult varies from 3 mg in New Zealand to 14 mg in some American cities. Up to 30 percent of tissue sellenium is contained in the liver, 15 precent in kidney and 30 precent in muscle, and 10 percent in blood plasma.

Sellenium helps control tissue concentrations of highly reactive oxygen-containing metabolites. It also protects against the damaging effect of oxygen-rich free radicals.

Sellenium can be toxic if taken in excess ( more than 400 micrograms per day)

Meats and seafood are a good source of sellenium, especially if the meat comes from animals growing in sellenium-rich soil. Brazil nuts are also a good source of sellenium.