Pectin and psyllium decrease the susceptibility of LDL to oxidation in guinea pigs

These studies were undertaken to determine whether pectin (PE) and psyllium (PSY) intake affect the circulating levels of alpha-tocopherol and the sus ceptibility of low density lipoprotein (LDL) to oxidation. For that purpose , male Hartley guinea pigs were fed 19 g/100 g of a fat mix with a 2:1:1 ra tio of saturated:polyunsaturated: monounsaturated fatty acids and 35 g/100 g total carbohydrate with 80% of the carbohydrate energy contributed by suc rose. Diets were identical in composition except for the fiber source: cell ulose (control diet), PE, or PSY. Guinea pigs fed PE ol PSY had 36% and 67% lower plasma cholesterol concentrations, respectively, compared with contr ols (P < 0.001). This plasma cholesterol lowering was associated,with both very low density lipoproteins and LDL cholesterol fractions. Intake of PE o r PSY resulted in 54% lower plasma triacylglyecrol (TAG) concentrations com pared with the control group (P < 0.001). LDL from PE and PSY fed guinea pi gs contained fewer molecules of cholesteryl ester, and alpha-tocopherol con centrations in this particle,were 49% and 66% higher, respectively, compare d with controls. In addition, LDL from guinea pigs fed soluble fiber exhibi ted less susceptibility to oxidation than those from the control group, as determined by thin barbituric acid-reactive substances formation. Hepatic f ree and esterified cholesterol were 32% lower and hepatic TAG was 25% lower in guinea pigs fed PE and PSY compared with controls. The data from these studies confirm that PE and PSY reverse the hyperlipidemia associated with high fat-sucrose diets and demonstrate a potential antioxidant effect of so luble fiber on circulating LDL. (C) Elsevier Science Inc. 1999. All rights reserved.