Comparative effects of chitosan and cholestyramine on lymphatic absorption of lipids in the rat.

The effects of chitosan and cholestyramine on intestinal absorption of oleic acid and cholesterol were assessed in adult male rats with cannulae in the thoracic duct lymphatic channel. In acute studies, 50 mg of either cholestyramine or chitosan were included in the test emulsion for intragastric administration. Over a 24-h lymph collection period, cholestyramine caused a 47% depression of cholesterol absorption and a 32% interference with oleic acid absorption. Chitosan had a similar effect on the absorption of both lipids under these conditions (51 and 41% depression, respectively). Studies were also conducted in animals fed for 4 wk on defined diets containing 1 and 5% levels of the test materials. Absorption of lipids from the standard aqueous emulsion was tested in lymph duct cannulated rats which had been fasted overnight. In these animals, prefeeding either cholestyramine or chitosan at the 1% level caused an 18 to 28% reduction in absorption of both lipids with greater variability in the chitosan-fed group. When either test material was fed at the 5% level, absorption of cholesterol was reduced by 63 to 69% and absorption of oleic acid by 58 to 62%. Although these agents may act by different mechanisms, the data suggest that chitosan is as effective as cholestyramine in its acute effects on lipid absorption and that, with chronic feeding, both materials cause equivalent adaptive changes in intestinal transport of administered fatty acid and cholesterol.