Interrelated effects of dietary fiber and fat on lymphatic cholesterol and triglyceride absorption in rats

Lymph cannulated rats were administered intragastrically a test emulsion containing 25 mg of [14C]cholesterol, 50 mg of either guar gum, cellulose or chitosan, and 200 mg of either safflower, high-oleic safflower or palm oil, and the absorption of labeled cholesterol and fatty acids was measured. The type of both dietary fiber (P less than 0.001) and fat (P less than 0.05) significantly influenced cholesterol absorption. A significant interaction of fiber and fat on cholesterol absorption (P less than 0.05) was also observed. Chitosan effectively lowered cholesterol absorption more than did guar gum or cellulose, and this effect was more significant when given with safflower or high-oleic safflower oil than with palm oil. When guar gum was the source of dietary fiber, dietary fats did not modify cholesterol absorption. Dietary fiber also significantly affected triglyceride absorption (P less than 0.05). Absorption tended to be low in the chitosan, high in the cellulose and intermediate in the guar gum group. Absorption of safflower and high-oleic safflower oils tended to be higher than that of palm oil when cellulose or guar gum was fed. Guar gum, as compared with the other fibers, altered the absorption pattern of both cholesterol and triglyceride. The results showed that the type of dietary fat significantly influenced the effect that dietary fiber exerted on lipid absorption.