DIETARY OXIDIZED OIL AND THE ACTIVITY OF ANTIOXIDANT ENZYMES AND LIPOPROTEIN PEROXIDATION IN RATS

The relationship between dietary oxidized oil and the activity of some antioxidant enzymes and the peroxidation state of plasma lipoproteins was studied with male growing rats. The animals were fed diets containing 10% fresh or oxidized soybean oil. Ingestion of the oxidized oil resulted in an elevation in the activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase in erythrocytes derived from the experimental rats compared to the controls. In contrast, in animals subjected to the oxidized oil, the hepatic activity of glucose-6-phosphate dehydrogenase was significantly lower, that of glutathione peroxidase and glutathione reductase showed a tendency to decrease, whereas the level of superoxide dismutase activity was unchanged. This could be explained by possible liver damage caused by the oxidized lipids, and indeed, the increased plasma levels of aspartate aminotransferase and alanine aminotransferase activity support this conclusion. Dietary oxidized oil increased the level of lipid peroxidation in various lipoprotein fractions. The study emphasizes the potential risk of dietary oxidized lipids.