Selenium was discovered by Berzelius in 1817. Eventually its electrical and optical properties were recognized, which stimulated a great deal of research and development in the electrophotographic field. This led to the use of selenium in the xerographic, or photocopy processes.

Initially there was little biological interest in the mineral selenium except for its toxic properties. Selenium toxicity was first recognized and described in animals. Cattle grazing on certain plants grown in seleniferous soil developed a peculiar condition called alkali disease, or blind staggers, which would eventually lead to death. It was believed that humans living in the same regions could also be affected by too much selenium, however, toxicity in humans was not readily recognized.¹

Interest in selenium increased due to the discovery of a selenium compound called "factor 3." This compound was found to protect animals from fatty infiltration and necrosis of the liver. This also led to the speculation that some type of relationship existed between selenium and vitamin E.² Research by Schwarz and Foltz, at the National Institutes of Health in 1957, found that selenium deficiency produced recognizable abnormalities in lab animals. They found that selenium supplementation reversed a condition called white muscle disease that occurred in sheep and cattle raised on selenium deficient soils. This led to the suspicion that selenium may be involved as a cofactor in enzyme systems related to cellular oxidation, and that selenium may therefore, play a role in human nutrition as well. The discovery that selenium deficiency was related to disease conditions brought selenium to the forefront as one of the latest essential nutrients.