SELENIUM IN HEALTH AND DISEASE - A REVIEW

Selenium (Se) was discovered 180 years ago. The toxicological properti es of Se in livestock were recognized first; its essential nutritional role for animals was discovered in the 1950s and for humans in 1973. Only one reductive metabolic pathway of Se is well characterized in bi ological systems, although several naturally occurring inorganic and o rganic forms of the element exist. The amount of Se available for assi milation by the tissues is dependent on the form and concentration of the element. Se is incorporated into a number of functionally active s elenoproteins, including the enzyme glutathione peroxidase, which acts as a cellular protector against free radical oxidative damage and typ e 1 iodothyronine 5'-deiodinase which interacts with iodine to prevent abnormal hormone metabolism. Se deficiency has been linked with numer ous diseases, including endemic cardiomyopathy in Se-deficient regions of China; cancer, muscular dystrophy, malaria, and cardiovascular dis ease have also been implicated, but evidence for the association is of ten tenuous. Information on Se levers in foods and dietary intake is L imited, and an average requirement for Se in the U.K. has no been esta blished. Available data suggest that intake in the U.K. is adequate fo r all, except for a few risk groups such as patients on total parenter al nutrition or restrictive diets.