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We have shown that cholesterol-fed diabetic rats developed atheromatous lesions in the aorta and coronary arteries, which were not observed in cholesterol-fed diabetic rats receiving concomitant supplementation with 15% glucomannan, a soluble dietary fiber concentrate. The present study was designed to examine the effects of the dietary fiber supplementation on serum levels of glucose and lipoproteins in cholesterol-fed diabetic rats. Feeding a diet containing 1.5% cholesterol (wt/wt) and 0.37% cholic acid for 18 weeks to rats made diabetic by streptozotocin (35 mg/kg body weight, iv) produced moderate hyperglycemia and moderate hypercholesterolemia, the latter being characterized by high concentrations not only of low density lipoproteins but also intermediate density lipoproteins and very low density lipoproteins. These changes in serum lipoproteins and hyperglycemia were substantially reduced by 18 weeks of supplementation with glucomannan but high density lipoprotein cholesterol and triglyceride levels did not change after feeding a cholesterol-rich diet in the presence or absence of glucomannan supplementation. These results suggest that amelioration in hyperlipoproteinemia and hyperglycemia induced by the dietary fiber supplementation may help retard or prevent the atheromatous formation found in cholesterol-fed diabetic rats.

The effects of long-term high-fiber diet on lipid and glucose levels and the histological changes in the coronary arteries and thoracic aorta in STZ-induced diabetic SD rats were investigated. During the first 4 weeks of the study period, all diabetic rats were given regular chow plus water after which, all were grouped according to the following diet regimen: group II, no added cholesterol and glucomannan; group III, no added cholesterol but with glucomannan supplement, group IV, with added cholesterol but no glucomannan supplement; and group V, with both cholesterol and glucomannan supplements. 15% weight of glucomannan and 1.5% weight of cholesterol in regular rat chow were used as supplements when indicated. Non-diabetic rats which received only regular chow served as the control group (group I). In the 18th week all rats were sacrificed and weight gain, glucose, total cholesterol, HDL-cholesterol, triglyceride and lipid peroxidase concentrations were determined. Selected portions of the heart and thoracic aorta were histologically examined. Weight gain was higher in rats supplemented with glucomannan than in those without glucomannan supplements, but the difference is not significant. A lowering tendency in glucose levels was likewise observed. Furthermore, total cholesterol and HDL-cholesterol levels were lower and higher, respectively in diabetic rats receiving glucomannan. Although the triglyceride levels were similar in all rats, lipid peroxidase levels were significantly lower in rats with high-fiber diet.(ABSTRACT TRUNCATED AT 250 WORDS)