THE EFFECT OF DIETARY LIPIDS ON THE SERUM CHOLESTEROL OF RATS

Abstract

Experimental conditions were devised under which the effect of dietary triglyceride oils on the serum cholesterol concentration of rats resembled the effect of these oils on man. No artificial additives were used in the diet. By the use of this technique, the hypocholesterolemic activity of sunflower seed oil was studied. The feeding of fractions prepared by chemical and physical means showed that the unsaponifiable matter was responsible for a substantial part of the hypocholesterolemic action of the unmodified oil. Several fractions with similar fatty acid compositions were prepared which had different effects on the serum cholesterol level. Some known compounds of the unsaponifiable matter were next fed, dissolved in coconut oil. β-Sitosterol and squalene had little effect but a combination of these with α-tocopherol and β-carotene produced a significant depressing effect. The administration of cholesterol with a fat-free diet did not raise the serum cholesterol level unless the sterol was given dissolved in oil. Increasing quantities of sterol of up to 6%, dissolved in oil, produced increasing serum levels. Larger quantities caused no further rise. The possibility that only dissolved cholesterol is absorbed is discussed.