The effect of dietary supplementation of β-carotene on lipid metabolism in streptozotocin-induced diabetic rats

Abstract

Vascular complications such as atherosclerosis hinder the treatment of diabetes. We hypothesized that moderate supplementation with β-carotene might help prevent diabetic vascular complications through its impact on lipid metabolism. Forty Sprague-Dawley rats were fed AIN-76 control diet, or the same diet supplemented with β-carotene (7.2 mg/kg diet) for 3 weeks, then diabetes was induced in half of the rats by streptozotocin. Diabetic and normal rats were fed the experimental diets for 2 more weeks. β-Carotene did not reduce blood glucose in diabetic rats. Plasma triglycerides were increased by diabetes, but reduced by β-carotene. Plasma total cholesterol was increased by diabetes. High-density lipoprotein cholesterol did not differ between groups. However, the atherogenic index of diabetic rats was higher than that of control rats, and β-carotene feeding decreased it. Fecal excretion of cholesterol and coprostanone was decreased by diabetes, and β-carotene tended to increase this excretion. Fecal excretion of bile acid showed similar tendencies, as did neutral steroids. These results suggest that dietary supplementation with β-carotene may reduce plasma triglycerides and other indices of diabetic risk, and thus may decrease the incidence of diabetic vascular complications through the normalization of lipid metabolism in patients with diabetes.