Selenium

Selenium is an essential mineral that the human body uses as a component of specialized proteins called selenoproteins. These proteins participate in processes including thyroid hormone metabolism, DNA synthesis, reproduction, and protection against oxidative damage. Selenium's biological importance therefore comes largely from the proteins into which it is incorporated, rather than from selenium acting as an isolated substance .¹

Selenium occurs in several chemical forms. Inorganic forms include selenite and selenate, while organic forms include selenomethionine and selenocysteine, in which selenium is part of an amino acid. Plants take up inorganic selenium and convert it into organic compounds. Selenium in food is found mainly as selenomethionine and also as selenocysteine .¹

After absorption, selenomethionine and inorganic selenium can enter a shared metabolic pathway used to make selenocysteine. This is the form incorporated into the 25 human selenoproteins. The body regulates its selenium balance mainly through urinary excretion .¹