Repeatedly heated cooking oils induced alterations in erythrocyte membrane integrity and antioxidant status in cholesterol fed Sprague Dawley rats

Abstract

Repeatedly heated cooking oils induce oxidative stress in animals. Erythrocytes are prone to free radical induced lipid peroxidation. This study compared the effects of repeatedly heated cooking oils on erythrocyte membrane changes in hypercholesterolemic rats. Coconut oil, mustard oil, and sunflower oil were heated at 210 ± 10°C for 15 hr. Fresh/heated oils (15%) and cholesterol (1%) were fed with experimental diet for 60 days. Chemical analysis showed deteriorative changes in heated oils, effect being lower in heated coconut oil. Elevated MDA and protein carbonyl content and compromised antioxidant status was observed in heated oil fed animals. Membrane bound enzymes were decreased and markers of in vivo hemolysis were significantly elevated in heated oil fed animals. Osmotic fragility of erythrocytes was also higher in heated oils fed groups. Our study shows increased lipid peroxidation associated with reduced antioxidant status of erythrocytes, make them more susceptible to hemolysis. Practical applications High fat and cholesterol are increasingly being included in the modern diet. Hypercholesterolemia and lipid oxidation are serious risk factors contributing to the pathogenesis of atherosclerosis. Thermally treated dietary fats in typical modern diets contain lipid peroxidation products. Cooking oils are repeatedly heated at high temperatures and reused for maximum profit during various food preparations. The nature of fatty acids influences the rate of lipid peroxidation occurring in oils during thermal treatments. The present study clearly showed that frying oils such as mustard oil and sunflower oil have lower stability than coconut oil because of high polyunsaturated fatty acid content. Results obtained from these investigations indicate that consumption of thermally oxidized cooking oil causes oxidative damage thereby increasing the risk of atherosclerosis. Hence for optimal use, it is necessary to distinguish the quality of oil and not to expose cooking oils to high temperatures for longer duration.