Dietary pectin with high viscosity lowers plasma and liver cholesterol concentration and plasma cholesteryl ester transfer protein activity in hamsters

Abstract

We fed semipurified diets containing pectin with either a high or low in vitro viscosity at a level of 3 g/100 g air-dried diet to hamsters for 8 wk. A control group was fed cellulose and a positive control group was fed psyllium. The pectins used were a calcium-sensitive pectin (CS-pectin) that has a high viscosity and a noncalcium-sensitive pectin (NCS-pectin) that has a low viscosity. In the presence of calcium, CS-pectin has a more than 80- fold higher viscosity than NOS-pectin which offered the opportunity to investigate the possible role of viscosity in the hypolipidemic properties of pectin. The hamsters fed CS-pectin or psyllium had considerably lower plasma cholesterol concentrations (3.69 ± 0.44 and 4.21 ± 0.45 mmol/L, respectively, mean ± SD, n = 14) than those fed NCS-pectin (5.03 ± 1.15 mmol/L) or cellulose (5.72 ± 1.04 mmol/L). Differences in total plasma cholesterol were reflected in both high density lipoprotein and very low density lipoprotein cholesterol. There was no effect of fiber on low density lipoprotein cholesterol levels. Liver cholesterol concentrations paralleled the plasma cholesterol levels and were 9.91 ± 2.48 μmol/g of liver for the CS-pectin group, 15.03 ± 5.75 for the psyllium group, 17.69 ± 10.66 for the NOS-pectin group, and 25.57 ± 9.23 for the cellulose group. Fecal bile acid and neutral steroid excretion tended to be higher in the hamsters fed CS- pectin than in their counterparts fed NCS-pectin. The hamsters fed psyllium had significantly greater fecal excretions of bile acids than the hamsters fed cellulose, CS-pectin or NOS-pectin, whereas the excretion of fecal neutral sterols tended to be lower. Plasma cholesteryl ester transfer protein activity was significantly lower in the hamsters fed CS-pectin than in those fed NOS-pectin. The results of this study suggest that the viscosity of pectins may determine their cholesterolemic effect.