CHOLESTEROL DYNAMICS IN RATS FED DIETS CONTAINING EITHER CANOLA OIL OR SUNFLOWER OIL

The hypothesis, that canola oil, rich in monounsaturated and n-3 fatty acids lowers total body cholesterol unlike sunflower oil rich in n-6 fatty acids which appears to redistribute the exchangeable body choles terol pools was tested. Male weanling Sprague-Dawley rats were fed nut ritionally adequate diets containing either canola oil (CO diet) or su nflower oil (SFO diet). A third diet, (CONTROL diet), containing prima rily beef tallow but sufficient amount of linoleic acid to prevent ess ential fatty acid deficiency was also employed. The effect of these di ets on serum cholesterol, HDL-cholesterol, serum triglyceride and live r cholesterol was examined. To study the exchangeable body cholesterol pools, the rats were gauvaged with [4-C-14]-cholesterol and radioacti vity incorporated into serum, liver, heart, testes, spleen, faeces and kidney at various time intervals was determined. There was a signific ant reduction in the HDL-cholesterol concentration following the feedi ng of SFO diet whereas CO feeding had no effect. The cholesterol conte nt in the hepatic tissue was increased by SFO diet while the CO had no significant effect as compared to the BT diet. Triacylglycerol concen tration in the serum was lowered by both the SFO and CO diets to the s ame extent when compared to the BT diet. The level of triacylglycerol in the liver was not significantly altered by any of the diet treatmen ts. Feeding sunflower oil containing diet to the rats resulted in high er incorporation of C-14-cholesterol in various pools examined in comp arison to the group fed the canola oil. Excretion of C-14-cholesterol and its metabolites in the faeces was highest in the animals fed the c anola oil containing diets. These data suggest that the liver accumula tion of cholesterol following the feeding of a diet rich in sunflower oil containing high levels of n-6 fatty acids may be due to rapid abso rption of cholesterol from the gut into the blood followed by rapid up take by liver and other tissues as well as reduced excretion of choles terol and its metabolites in the faeces. Copyright (C) 1997 Elsevier S cience Inc.