Effects of fish oil and vitamin E on the antioxidant defense system in diet-induced hypercholesterolemic rabbits.

This study was designed to investigate the effects of fish oil and vitamin E on the antioxidant defense system in hypercholesterolemic rabbits. A high fat and cholesterol diet, with or without supplement by fish oil and/or a vitamin E supplement, was fed to rabbits for 6 weeks. Compared to the reference diet of regular laboratory rabbit chow, a high fat and cholesterol-enriched diet increased atheroma formation, plasma lipid and peroxide levels, decreased blood glutathione levels, and reduced plasma glutathione reductase, glutathione peroxidase, and catalase activities. Fish oil supplementation significantly reduced atheroma and increased glutathione reductase and glutathione peroxidase activities and blood glutathione levels, but increased plasma lipid peroxide levels. Vitamin E supplementation of the fish oil diet enhanced the beneficial effects by increasing glutathione reductase activity and decreasing peroxide levels. These results indicate that a high fat and cholesterol diet attenuates blood glutathione levels and plasma antioxidant enzyme activities, which may account for some of its atherogenic properties. Consumption of fish oil enhances antioxidative defenses against the oxidative stress imposed by hypercholesterolemia, and vitamin E further enhances these beneficial effects.