Factors Influencing Cholesterol Absorption

Abstract

Fat in adequate quantities facilitated the absorption of cholesterol as detd. by the difference between dietary and fecal sterol levels. The fatty acid portion of the neutral fat molecule was the active factor facilitating cholesterol absorption. Serum cholesterol levels were higher in animals receiving cholesterol and oleic acid than in those receiving cholesterol and corn oil. Cholic acid added to the diet raised the serum cholesterol levels in rats receiving cholesterol and oleic acid. Cholic acid or desoxycholic acid added to the diet did not raise serum cholesterol levels significantly in rats receiving cholesterol and corn oil. Fecal excretion of phospholipid varied with the diet. With a fat-free diet the feces contained only a trace of phospholipid and the addition of cholesterol or glycerol did not alter the phospholipid excretion. When corn oil was fed appreciable amts. of phospholipid appeared in the feces and this was further increased by feeding various free fatty acids. Oleic acid was more potent than palmitic acid in stimulating phospholipid excretion. The addition to the diet of free fatty acids derived from corn oil increased the fecal phospholipid excretion 14 times above the level seen when an equivalent amt. of corn oil was fed. About 7% of the corn oil fatty acids was split off in the intestine prior to absorption. Thiouracil increased serum cholesterol sigificantly even when the diet contained neither fat nor cholesterol. Cholesterol did not prevent the wt. loss induced by feeding thyroid powder. But corn oil diminished wt. loss considerably. There was a marked sex difference in response to thyroid powder. Desoxycholic acid was more toxic to male than to female rats. Male rats were protected by dietary additions in the order of their effectiveness: cholesterol, corn oil, and cholesterol plus corn oil.