Combined effect of vitamins C and E on zinc status, carbohydrate metabolism and antioxidant values in diabetic rats fed zinc-deficient diet

Abstract

The aim of this study was to investigate the combined effect of vitamin C and vitamin E on carbohydrate metabolism, zinc status and antioxidant enzymes activities in diabetic rats fed low zinc diet. Female diabetic albino Wistar rats were randomly assigned into five groups. The first group received a diet containing a 54 mg zinc/kg diet (adequate zinc, AZ), the second group received a diet containing 1 mg zinc/kg diet (zinc deficient group, ZD), and the three other groups received ZD diet and treated orally with vitamin E (500 mg/kg body wt) (ZD+VitE), vitamin C (500 mg/kg body wt) (ZD+VitC), and combined vitamins C and E (250 + 250 mg/kg body wt) (ZD+VitC+VitE) respectively. Body weight and food intake were recorded regularly. After four weeks of dietary manipulation. Serum and tissues zinc concentration, alkaline phosphatase activity of low-zinc diabetic animals were significantly lower than those of the control diabetic animals. Dietary zinc deficiency also increased significantly blood glucose, HbA1c, cholesterol and triglycerides concentrations, glutamate oxaloacetate transaminase, glutamate-pyruvate transaminase activities, and malondialdehyde level of low zinc diabetic rats. In contrast, catalase and glutathione peroxidase activities and liver glutathione level were reduced. Vit C or vit E may have partial ameliorative effects on these disturbances, whereas vit C and vit E together assured a more efficient protection. In conclusion vitamin E and C act as beneficial and potent antioxidants protect against lipid peroxidation and oxidative damage due to zinc deficiency associated with diabetes mellitus.