Effects of α‐tocopherol and β‐carotene on hepatic lipid peroxidation and blood lipids in rats with dietary iron overload

Abstract

The ability of dietary antioxidants to reduce lipid peroxidation induced by iron overload was examined in weanling male Sprague‐Dawley rats. Animals were fed ad libitum a modified AIN‐76A diet (control) or control diet with 0.5% α‐tocopherol acid succinate, 0.5% crystalline trans‐β‐carotene, or 0.5% α‐tocopherol acid succinate + 0.5% trans‐β‐carotene for four weeks. In the following four‐week period, the animals received the above diets with 10,000 μg Fe/g; a control group continued to receive 35 μg Fe/g, and a high‐iron group received 10,000 μg Fe/g with no antioxidants. After four weeks of dietary supplementation with α‐tocopherol, β‐carotene, or α‐tocopherol + β‐carotene, liver concentrations of α‐tocopherol and β‐carotene increased significantly (p < 0.001). Liver lipid peroxidation, measured by the lipid‐conjugated diene assay, increased significantly from 0.012 μmol/mg of lipid in the controls to 0.021 μmol/mg of lipid in animals receiving the high‐iron diet. However, lipid peroxidation was significantly reduced in all animals fed the antioxidants, with the group fed α‐tocopherol + β‐carotene having a lower level than the high‐iron group. Total serum cholesterol was elevated in animals fed a high‐iron diet and in animals fed the high‐iron diet with α‐tocopherol. In contrast, total serum cholesterol levels in the two groups of animals receiving the diets containing high iron with β‐carotene alone or high iron with β‐carotene + α‐tocopherol were significantly reduced to the level of the control group. High‐density lipoprotein cholesterol also decreased to baseline in the animals receiving β‐carotene alone. Modulation of lipid peroxidation by α‐tocopherol or β‐carotene may be an important mechanism for reducing oxidative stress.