Soy fiber improves lipid and carbohydrate metabolism in primary hyperlipidemic subjects

This study was designed to evaluate the effects of soy fiber, a natural source of dietary fiber that consists of both cellulosic and noncellulosic dietary fiber, on human plasma lipoprotein lipids and glucose tolerance in patients with primary hyperlipidemia. Supplementing 25 g of soy fiber per day provided a significant additional reduction of plasma total-cholesterol by 13 mg/dl (P less than 0.04) and LDL cholesterol by 12 mg/dl (P less than 0.05) beyond that previously achieved by treatment with an NIH Type II-A low-fat, low-cholesterol diet for 12 weeks in Type II-A hypercholesterolemic patients. There were no effects on HDL cholesterol or apoprotein A-I and A-II levels. The hypocholesterolemic effect was greater than in the hyperlipidemic patients with impaired glucose tolerance. Soy fiber supplementation also significantly reduced insulin responses to oral glucose challenge by 20% in Type II-A hypercholesterolemic and by 16.5% in Type IV hypertriglyceridemic patients. Results from this study suggest that supplementing the diet with soy fiber may be beneficial in dietary management of hyperlipidemia in patients with hypercholesterolemia and particularly in hyperlipidemic patients with hyperinsulinemia and impaired glucose tolerance.