Effects of dietary omeg-3 fatty acid supplementation on HbA1c, total antioxidant capacity and superoxide dismutase and catalase activities in type-2 diabetic patients: A randomized clinical trial

Essential fatty acid deficiency has been found in diabetic patients. Omega-3 fatty acid supplementation could be beneficial in alleviating diabetes complications and glycemic control. However, it may increase oxidative stress. In this study the effects of omega-3 fatty acid supplements on glycemic control, total antioxidant capacity and antioxidant enzymes (superoxide dismutase and catalase) activities were investigated. In a double-blind, randomized, controlled clinical trial, 81 type-2 diabetic patients were divided into 2 groups. The experimental group took 2714 mg/day omega-3 fatty acids (1548 mg EPA, 828 mg DHA, and 338 mg other omega-3 fatty acids), and the control group took sunflower oil as a placebo, for 8 weeks. Dietary intakes were assessed by a 24h dietary recall, before and after intervention, and analyzed using food processor II. In addition, fasting blood samples were collected for analysis and height and weight were measured, initially and at the end of the trial. At the start of the study there were no statistically significant differences between the two groups with regard to mean weight, height, body mass index (BMI), daily intakes of energy, carbohydrate, protein, total fat, polyunsaturated fatty acids, fiber, vitamins A, B, C, E, folate, cobalamine, zinc, or biochemical parameters. Neither were there any difference in weight, BMI and dietary intakes before and after intervention in either group. The supplementation brought about a significant decrease (P<0.00) in HbA1c% in the experimental group, while in the control group the HbA1c level actually increased (p<0.02). Furthermore, the magnitudes of HbA1c changes were significantly deferent between the two groups (P<0.00). Changes in the fasting blood sugar (163.88 ± 10 vs. 165.6 ± 7.9 mg/dl), total antioxidant capacity (3.79 ± 0.07 vs. 3.62 ± 0.7 mg/dl), and activities of super oxide dismutase (449.22 ± 14.14 vs. 417.16 ± 11.9 U/gHb) and catalase (150.72 ± 9.6 vs. 151.86 ± 12.6 k/gHb) were not statistically significant. Omega-3 fatty acid supplementation may be helpful in glycemic control in type-2 diabetes, but it has no significant effect on the antioxidant enzyme activities.