Effect of High Levels of Dietary Vitamin E on Liver and Plasma Lipids and Fat Soluble Vitamins in Rats

Abstract

The effect of low, moderate and high dietary vitamin E (ranging from 0 to 25,000 IU/kg diet) on the levels of alpha-tocopherol, total lipids, cholesterol and vitamin A in liver and plasma of rats fed for 8 and 16 months was studied. A logarithmic relationship was observed between dietary levels of vitamin E and the concentrations of this vitamin in liver and plasma. The total alpha-tocopherol in whole liver of rats fed different levels of dietary vitamin E for 16 months was approximately double in comparison to rats fed for 8 months. Totoal lipids in liver were significantly increased by excess vitamin E supplementation in rats fed for 8 months, but not in rats fed for 16 months. There was no significant change observed in liver cholesterol level at 16 months. Plasma total lipids and cholesterol were lowered by vitamin E deficiency and also by dietary levels higher than 2,500 IU vitamin E/kg diet in rats fed for 16 months. Liver vitamin A storage was 4.5 times higher in rats supplemented with vitamin E than in rats without any supplement, but the effect of excess dietary vitamin E was no different from that of normal level (25 IU/kg diet). The findings of our long-term study are compared with the results of other short-term studies and the implications are discussed.