Comparative effects of repeatedly heated cooking oils on tissue lipid peroxidation and antioxidant status in cholesterol-fed Sprague Dawley rats

Purpose The purpose of this paper is to compare the effects of repeatedly heated coconut oil, mustard oil and sunflower oil on antioxidant status in cholesterol-fed Sprague Dawley rats. Design/methodology/approach The test oils were heated at 210 +/- 10 degrees C for 15 h. Male Sprague Dawley rats were divided into six groups of six animals each. In total, 15% fresh/heated oils and 1% cholesterol were mixed with the experimental diet and fed to the animals for 60 days. Findings Chemical analysis revealed that repeated heating of oils resulted in changes in fatty acid composition and elevated lipid peroxidation, the effects being lower in heated coconut oil. Body weight gain significantly decreased in heated coconut oil (p= 0.02), heated mustard oil (p= 0.022) and heated sunflower oil (p= 0.001) fed animals. Malondialdehyde level was significantly increased (p= 0.001) in tissues of heated oils fed animals. Concentration of protein oxidation products was significantly increased (p= 0.001) in heated oils fed animals. Activities of antioxidant enzymes were decreased (p= 0.001) in heated oils fed animals. Total thiols were decreased (p= 0.001) in tissues of animals that were fed heated oils. Animals that were fed heated mustard oil and heated sunflower oil showed lower antioxidant levels and higher oxidation products when compared to those fed heated coconut oil. Originality/value Studies comparing the effects of thermally oxidized oils that vary in fatty acid composition are rare. The effects of fresh and heated oils that vary in fatty acid constitution, namely, coconut oil, mustard oil and sunflower oil, in cholesterol-fed rats are studied.