The Effect of the Mediterranean Diet on Serum Total Antioxidant Capacity in Obese Patients: A Randomized Controlled Trial

Objective: The aim of this work was to evaluate the combined effect of physical activity and 1 and 12 months' adherence to Mediterranean diet (MD) on serum total antioxidant capacity (TAC) in obese patients, as well as factors contributing to TAC. Methods: One hundred twenty-four patients were randomly assigned to either MD combined with physical activity or standard hypolypemic diet (SHD) with physical activity. Both groups received counseling and education during the initial week and were invited for the follow-up visits, where data on body weight and blood samples were collected. TAC was determined by Trolox equivalent antioxidant capacity and urate was determined using a uricase spectrophotometric method at the initial visit and after 1 and 12 months. Results: Eighty-four patients finished the 12-month program and were analyzed. The baseline and 1- and 12-month mean (+/- SD) TAC values in the MD group (n = 40) were 2.38 +/- 0.48, 2.51 +/- 0.47, and 2.47 +/- 0.45mmol Trolox equivalent (TE)/L, respectively. In the SHD group (n = 44), TAC values were 2.37 +/- 0.49, 2.48 +/- 0.49, and 2.31 +/- 0.51mmol TE/L, respectively. There was a statistically significant main effect for time (p < 0.001), as well as statistically significant time-diet interaction effect (p = 0.009). There was no statistically significant correlation between TAC and uric acid after 1 month (p = 0.733) or 12 months (p = 0.844) of the intervention. Based on the regression model, which included gender, diet, physical activity level, and percentage body weight change, the type of diet was the only significantly contributing factor to TAC change after the 12-month period, F = 3.867, df = 3, p = 0.012, R = 0.358, R-2 = 0.128. Conclusion: This randomized controlled trial with diet and physical activity intervention and TAC as a primary outcome demonstrated initial antioxidant improvement in both MD and SHD groups and a long-term beneficial effect of MD. The results imply that diet composition-olive oil, nuts, and fish in particular-combined with physical activity modify antioxidant capacity.