抄録
Three groups of weanling male rats were fed diets containing 20% palm oil, palm olein, or soybean oil as a control, for 28 days. Serum, liver, adipose tissue, and feces from these rats were used for analyzing cholesterol and its metabolites. The chemical and physical properties of palm oil and its fractionated oils were also examined.
1) Palmitic acid in palm oil was predominantly located at the 1-or 3-position of triglyceride, while oleic acid, the 2-position. By fractionating the palm oil into the stearin and the olein fractions, saturated triglycerides, such as tripalmitin, high melting point components in palm oil could be concentrated into the stearin fraction.
2) No significant differences in the concentrations of total and HDL-cholesterol, triglycerides and total bile acids in serum could be detected among rats fed palm oil, palm olein and soybean oil. Palmitic acid, rich in palm oil and palm olein, was found present as a minor constituent in serum lipids of rats fed these oils, and preferentially excreted in the feces.
3) Cholesterol content in both liver and adipose tissue was essentially the same in the palm oil and palm olein groups, and soybean oil group, while the content of cholesterol and its metabolites in the feces of the former two groups were significantly lower than those of the latter group. However, the ratio of the metabolites to cholesterol in the feces was basically the same among the three groups. Thus possibly, the effect of palm oil or palm olein on cholesterol metabolism in rat may be equivalent to that of soybean oil.
4) Based on the above findings, the preferential excretion of palmitic acid, rich in palm oil and palm olein in the feces may possibly be due to the absence of any differences in serum cholesterol levels in rats fed one of these oils and soybean oil.
