Symposium 2 Newer aspects of micronutrients in at risk groups

Adequate supplies of the micronutrient Se are required for normal health in both man and animals.Since the recognition of the essentiality of Se, decreased dietary Se supplies have been associated with a large number of clinical conditions.Additionally, Se supplementation of rodents has a beneficial role in the prevention of certain chemicallyinduced cancers.These findings have been the subject of a number of recent publications and are summarized in Table 1.The first functional selenoprotein to be identified was cytosolic glutathione peroxidase (cGSHPx; Rotruck et al. 1973).Despite the recognition that a number of proteins could be specifically-labelled with '%e, for several years cGSHPx remained the only identified, functional selenoprotein (Behne et al. 1988; Evenson & Sunde, 1988; Bansal et al. 1991).Consequently attempts were made to explain the role of Se in the prevention of many apparently unrelated diseases as antioxidant effects of cGSHPx.Also, since cGSHPx in blood and tissues reflects dietary Se intake the enzyme activity has been used as an index of nutritional Se status (Hoekstra, 1975; Combs & Combs, 1986).In recent years, however, several more selenoproteins have been characterized either by purification and sequencing of the protein and/or by cloning and sequencing of cDNAs.The purpose of the present short review is to describe some of these newly identified selenoproteins and how they may function in conferring the nutritional essentiality of Se.Table 1.Some conditions and functional changes associated with selenium