Effects of Dietary Palm Oil and Tocotrienol Concentrate on Plasma Lipids, Eicosanoid Productions and Tissue Fatty Acid Compositions in Rats

Abstract

Palm oil (PA) contains about 50% saturated fatty acid and is rich in tocotrienol (T-3). Plasma lipid and eicosanoid levels, and fatty acid compositions of tissue lipids in rats given refined PA were compared to those given lard (LA) rich in stearate, olive oil (OL), palm olein rich in oleate, and safflower oil (SA) rich in linoleate. The effects of supplementation with T-3 was also investigated. An elevation of the plasma cholesterol level due to cholesterol feeding was moderate in rats given PA or LA compared to rats given OL, although it was higher than in the SA group. The proportion of linoleate in dietary PA, LA and OL was similar, but that of arachidonate in plasma phosphatidylcholine and platelet lipids was slightly but significantly higher in the PA group, when compared to the SA group, but the proportion of docosahexaenoate in plasma and liver phosphatidylcholine was significantly lower in the PA group than that in the LA and OL groups. Although aortic production of prostacyclin and the plasma level of thromboxane A₂ did not differ significantly among rats fed various fats, the ratio of prostacylin/thromboxane A₂ was in the following order: SA > PA = LA > OL. The addition of T-3 to PA did not affect plasma total cholesterol, eicosanoids, or tissue fatty acid compositions, but plasma high density lipoprotein-cholesterol increased dose-dependently. This study, therefore, suggests that both the fatty acid composition and T-3 affect the metabolic effect of dietary fat on plasma cholesterol, tissue polyunsaturated fatty acids, and probably eicosanoid balance.Α