Effect of dietary fats and barley fiber on total cholesterol and lipoprotein cholesterol distribution in plasma of hamsters

Abstract

Dietary saturated fatty acids and cholesterol elevate blood lipids, promote hypercholesterolemia and lead to elevation of circulating very low density (VLDL) and low density lipoproteins (LDL). Dietary fiber is suggested to ameliorate hypercholesterolemia. This study was undertaken to determine if dietary fiber would alter the quantity and distribution of cholesterol among plasma lipoproteins in the well-described model of dietary fat-induced hypercholesterolemia, the golden Syrian hamster. Hamsters were fed a basal high fat diet with 2.5% safflower oil and 10% butterfat to which had been added either 2.5% olive oil or 2.5% fish oil. Fiber was provided as cellulose or beta-glucan-enriched barley fiber at 10% of the diet. In hamsters fed 10% butterfat, 2.5% olive oil and cellulose, plasma cholesterol content was 237 mg/100 mL, with 65% of the total plasma cholesterol distributed in high density lipoproteins (HDL) and 35% in LDL plus VLDL. In hamsters fed 10% butterfat and 2.5% fish oil and cellulose, total cholesterol was 297 mg/100 mL, and 32% of the cholesterol was associated with HDL and 68% with LDL plus VLDL. These data indicated a significant redistribution of cholesterol from the HDL to the LDL and VLDL in fish oil fed animals. Substitution of barley fiber for cellulose in diets tended to decrease plasma cholesterol, however, it did not significantly affect the distribution of cholesterol among the lipoprotein classes. Serum triglycerides were higher in plasma of hamsters fed fish oil, and fiber did not alter either total triglycerides or distribution of triglycerides among lipoprotein classes. This study suggested that cholesterol distribution in plasma of hamsters fed cholesterolemic diets is more responsive to dietary fat than fiber and is due to mechanisms additional to hepatic LDL-receptor binding activity.