Effects of Vitamin E Supplementation on Antioxidation and Lipid Profiles of Rats on Diets Supplemented with Cholesterol and Olive Oil

Lipid peroxidation (LPO) has been identified as an important component of atherosclerosis. In this study, the effects of supplementation with cholesterol (0.5%), olive oil (5%) and vitamin E (0.05%) on erythrocyte glutathione (GSH), plasma malondialdehyde (MDA), total cholesterol, HDL-LDL cholesterol and triacylglycerol, brain and liver MDA and GSH concentrations of rats were investigated. A total of 50 Sprague-Dawley male rats aged 6 months, and of equal body weight were used and fed a standard ration ad libitum. Animals were housed in the University of Selcuk, Veterinary Faculty Experimental Animals Unit. The experiment lasted 60 days and there were five experimental groups as follows: 1. Control, 2. Cholesterol (0.5%), 3. Olive oil (5%), 4. Cholesterol plus vitamin E (0.05%), 5. Olive oil plus vitamin E (0.05%). At the end of the experiment, blood samples were taken by cardiac puncture and erythrocyte GSH, plasma MDA, cholesterol, HDL-LDL cholesterol, triacylglycerol and also GSH and MDA concentrations in brain and liver tissue of rats were spectrophotometrically determined. Supplementation of olive oil and cholesterol into rat diets (groups 2 and 3) caused significant differences in lipid parameters; HDL cholesterol concentrations were increased in the olive oil group and LDL cholesterol was lower than in the cholesterol fed group. Moreover, these decreases in LDL and triacylglycerol concentrations were more significant with vitamin E supplementation. The high plasma MDA concentrations showed that lipid peroxidation occurred in the olive oil group and the highest brain MDA concentrations were determined also in the olive oil group. These findings suggest that vitamin E addition may decrease the sensitivities of several oils to oxidation and that monounsaturated fatty acids in olive oil may decrease the incidence of atherosclerosis by regulating blood lipid profiles.