Effects of Legume Supplementation on the Glucose and Lipid Metabolism and Lipid Peroxidation in Streptozotocin-Induced Diabetic Rats

ABSTRACT

The present study was conducted to evaluate the usefulness of common Korean legumes as a high-fiber supplement in therapeutic diets for diabetic patients. Streptozotocin-induced diabetic rats were used as animal models and four kinds of legumes, black soybean (BS), yellow soybean (YS), green pea (GP) and soybean curd residue (SCR) were tested as high-fiber supplements. Seven groups of normal and streptozotocin-induced diabetic rats were fed isocaloric experimental diets containing 8% dietary fiber from one of four legumes or purified cellulose and pectin for 6 weeks. The effects of the legumes on the glucose and lipid metabolism of diabetic rats was examined and compared with the effects of cellulose and pectin. The legume supplementation did not show any beneficial effect on glucose tolerance, however, it exhibited a plasma cholesterol-lowering effect in diabetic rats. The cholesterol-lowering action was especially strong in BS and the degree of the effect was comparable to that of pectin. The levels of total lipids, cholesterol, and triglyceride in the hepatic tissues of rats fed legume diets were similar to those of the pectin group. All legume supplements induced an increase in fecal steroid excretion. The fecal cholesterol contents were significantly high following the supplementations of YS and SCR (p<0.05). The excretion of fecal bile acids in the BS and YS groups was significantly higher than it was in the pectin group (p<0.05). Concentration of lipid peroxidation products in the blood and urine of diabetic animals was lower in the legume groups than in the cellulose group. The levels of hepatic lipid peroxidation products were significantly lower in the BS and YS groups than in the pectin group (p<0.05). From the results of this study, the plasma cholesterol-lowering effect of BS is possibly due to the significant (p<0.05) in-crease in fecal steroid excretion, which suggests that BS could be beneficial in improving abnormal lipid metabolism in diabetic rats.