Metabolic Aspects of Selenium Action and Toxicity

The nutritional observations, on which the activity of selenium is based, are briefly reviewed, and the interactions of the trace element with vitamin E, polyunsaturated fatty acids, and sulfur amino acids at the dietary level highlighted. Brief mention is made of early morphological effects of vitamin E and selenium deficiency and of “classical” interpretations of these in biochemical terms. The concept is developed, based on recent observations in a number of laboratories, that selenium participates in enzyme systems that have an oxidation/reduction role. In this connection, work on glutathione peroxidase on a selenoenzyme of lamb nuscle, on certain bacterial reductases, and on rat liver electron-transfer systems is discussed.The toxicology of selenium is reviewed briefly, and interactions of the element with mercury, cadmium, silver, and arsenic are discussed. Mechanisms for selenium detoxication are considered, and probable biochemical pathways for treatment of toxic amounts of selenium are set out. Finally, an attempt is made to link together in biochemical terms the modes of treatment and utilization of selenium as a trace element with the pathways for the detoxication of large amounts of the element.