The aim. To determine the effect of high-fat diet (HFD) using fats of different fatty acid composition on the content of malondialdehyde (MDA) in the organs and tissues of rats and on catalase activity. Materials and methods. The following edible fats were used: regular (high linoleic) sunflower oil, high oleic sunflower oil, palm, butter and coconut oils at a concentration of 15 % by weight of the diet. The rats were fed for 64 days. Before euthanasia, rats were bled from v. porta and v. cava inferior. The MDA content and catalase activity were determined in blood serum, in liver homogenates, intestinal mucous membranes, in skeletal muscles, heart and brain. The antioxidant-prooxidant index of API was
calculated from the ratio of catalase activity and MDA content. Results. found that the content of the MDA in v. cava is significantly higher than v. porta. High-fat diet (HFD) increases the MDA content in all tissues except the brain, and most of all in the liver and after the consumption of high-palmitic fats (palm and butter), as well as high-linoleic sunflower oil. The exception is high oleic sunflower oil, the consumption of which does not increase the MDA content. Catalase activity reacts little to HFD. Conclusions. the liver secrete MDA into the blood. HFD increases the level of MDA in organs and tissues, except for the brain, without significantly reducing the activity of catalase. The antioxidant effect of HFD using high oleic sunflower oil can be explained by the antioxidant properties of oleic acid
