Influence of dietary peroxides, selenium and vitamin E on glutathione peroxidase of the gastrointestinal tract.

The influence of dietary peroxides, vitamin E and selenium on glutathione peroxidase (GSH-Px) activity in the gastrointestinal tract of the rat was investigated. Feeding 7% oxidized stripped corn oid (peroxide value 1,000) in a diet adequate in selenium and vitamin E increased the specific activity of GSH-Px in the stomach mucosa. Feeding oxidized oil produced an increase in the wet weight of the intestinal mucosa which was associated with a decrease in the specific activity of the enzyme. Total GSH-Px activity in the intestinal mucosa was unchanged or moderately increased. These changes were unaffected by the presence of vitamin E in the diet. Dietary peroxides had no effect on GSH-Px activity in the plasma or in the perirenal and paraepididymal adipose tissues. Subacute vitamin E deficiency had no consistent effect on the activity of the enzyme in several tissues examined. In rats fed a Se deficient diet glutathione peroxidase activity decreased markedly in most tissues but only slightly in the intestinal mucosa. The moderate decrease in the intestine may be explained by the accessibility of residual dietary Se to the mucosal cells. The role of Se in the detoxification of peroxides in foods and the response of gastrointestinal GSH-Px to dietary peroxides are discussed.