The Effect of n-3 Polyunsaturated Fatty Acids Supplementation on Serum Irisin in Patients with Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND Diabetes refers to a group of metabolic diseases with blood glucose of higher than normal ranges. Furthermore, n-3 polyunsaturated fatty acids are necessary for the regulation of the activity of human function. The effect of n-3 PUFA on diabetes has been investigated in animal studies, yet, the exact amount has not been set, to date. Irisin, as a new myokine, is released from skeletal muscle and Irisin levels decrease as a result of physical inactivity, overweightness, and obesity. Also, the reduction of serum irisin level is associated with development of insulin resistance and type 2 diabetes. This study was performed to assess the effects of n-3 PUFA supplementation on serum irisin level in patients with diabetes. METHODS This randomized clinical trial included 43 patients with type 2 diabetes (21 patients in the placebo group and 22 patients in the n-3 PUFA supplement group). They were randomized to groups, one receiving 10 weeks of either n-3 PUFA supplement and the other the placebo (1250 mg capsule, three times per day). Samples were also matched by age, gender, and body mass index (BMI) in the 2 groups. Anthropometric measurements, demographic information and dietary intakes were obtained both before and after the intervention. Serum irisin levels were measured before and after the intervention using human irisin enzyme linked immunosorbent assay (ELISA) kit. Independent t-test was used to compare the mean outcomes between groups. RESULTS At baseline, irisin serum levels were not significantly different between the placebo and n-3 PUFA supplementation groups (P > 0.05). However, a significant change was observed between the groups after intervention (P = 0.04). Also there was a significant difference in mean change (after versus before the intervention) (P = 0.05). Compared to the placebo, n-3 PUFA supplementation decreased serum FBS and HbA1C (P = 0.036 and 0.001; respectively). Also, there were significant differences between changes of diastolic blood pressure and HOMA-IR after the intervention between the groups. The duration of illness was not considered as a confounding factor because there was no significant association between irisin level (after versus before the intervention) and the illness duration. CONCLUSIONS The current study indicated that n-3 PUFA supplementation with a dosage of 1250 mg three times per day, resulted in increased serum irisin level of diabetic patients.