Effects of muscadine grape products on healthy and type 2 diabetic subjects: Blood chemistry, antioxidant capacity and membrane lipids

Objective. Red wines and grape juices contain phenolic compounds with antioxidant properties believed to be protective against oxidative stress conditions that are associated with cardiovascular events including hypertension, insulin resistance and Type 2 Diabetes. This study was designed to evaluate the effects of muscadine grape juice, muscadine grape wine and dealcoholized muscadine grape wine on blood constituents, antioxidant capacity, and erythrocyte membrane lipids of Type 2 diabetics and control, non-diabetic subjects. Methodology. Control subjects were randomized into 2 groups: control group without supplementation (n = 15), and control group on muscadine juice (n = 8). Type 2 Diabetics were in the following categories: muscadine juice (n = 10), dealcoholized wine (n = 9) and muscadine wine (n = 10) groups. In addition to their regular diet, each group consumed 150 ml of the grape product. A 3-day diet record, anthropometric indices and blood pressure were recorded. Blood samples were obtained for the analyses of erythrocyte membrane lipid, plasma total polyphenols, oxygen radical absorbance capacity (ORAC), total reduced glutathione, glycated hemoglobin and insulin. A comprehensive metabolic panel, blood coagulating indices, liver, renal and cardiac function tests were determined. All tests were carried out at baseline and 28 days post-treatment. Results. Glucose and glycated hemoglobin decreased post supplementation in all T2D groups, with the greatest decrease observed among the T2D-wine group. Dietary chromium and biotin levels were below 50% of recommended daily value for all subjects. Serum sodium and chloride levels significantly decreased in the T2D-wine group compared to their counterparts. Blood folate and vitamin B12 increased significantly in the T2D taking dealcoholized wine compared to T2D who consumed wine. Trends of lowered triglyceride (TG), total cholesterol (TC) and low density lipoprotein cholesterol (LDL) were observed among T2D taking dealcoholized wine and T2D taking wine compared to T2D taking juice. Alanine aminotransferase (ALT) and aspartate transaminase (AST) were significantly lower in T2D taking wine compared to T2D who consumed dealcoholized wine. Increased ORAC values post supplementation compared to baseline were not significant. Conclusion. Decreased levels of blood glucose and glycated hemoglobin post supplementation indicated better glycemic control, especially in the T2D-wine group. Low dietary chromium and biotin indicates insulin inefficiency in stimulating glucose uptake. Reduced serum sodium and chloride levels among T2D-wine group after supplementation suggest reduced risk for hypertension. High folate and vitamin B12 levels in T2D on dealcoholized wine indicate a favorable environment for homocysteine clearance and increased insulin sensitivity. Lowered TG, TC and LDL among T2D taking wine and DzW suggest improved lipid metabolism. Decreased ALT and AST in T2D-wine group indicates better insulin sensitivity and reduced risk of impaired liver function. Finally, T2D-wine and DzW groups exhibited improved serum lipids, ALT, AST and glutathione compared to T2D-juice group. Also, improved serum electrolyte and cardiac function in T2D-wine group, and greater responses in insulin, folate and vitamin B12 in T2D-DzW group were observed. Moderate amounts of wine and dealcoholized wine intake may therefore improve diabetic metabolic functions.