BackgroundPolycystic ovary syndrome (PCOS) is the most common endocrine disease in reproductive age women. The present study aimed to determine the effects of Dietary Approaches to Stop Hypertension (DASH) diet on reproductive hormones, plasma total antioxidant status and anthropometric indices in overweight and obese PCOS women. MethodsIn this randomised controlled clinical trial, 60 women with PCOS were randomly assigned to one of two diets with energy restriction: the DASH diet and a control diet. The DASH and control diets consisted of 50-55% carbohydrate, 15-20% protein and 25-30% total fat. The DASH diet was designed to be rich in vegetables, fruits, whole grains and low-fat dairy products, as well as low in saturated fats, cholesterol, refined grains and sweets. In the present study, the anthropometric indices, body composition, total testosterone, androstenedione, sex hormone binding globulin (SHBG), free androgen index and 2,2-diphenyl-1-picryylhydrazyl (DPPH) scavenging activity were measured before and after 3 months. ResultsThe consumption of DASH diet compared to the control diet was associated with a significant reduction in weight [-5.78 (1.91) kg versus -4.34 (2.87) kg, P = 0.032], body mass index (BMI) [-2.29 (0.15) kg m(-2) versus -1.69 (0.20) kg m(-2), P = 0.02], fat mass [-3.23(1.66) kg versus -2.13 (1.26) kg, P = 0.008] and serum androstenedione [-1.75 (1.39) ng mL(-1) versus -1.02 (0.72) ng mL(-1), P-value = 0.019]. Increased concentrations of SHBG [28.80 (21.71) versus 11.66(18.82) nmol L-1, P = 0.003) and DPPH scavenging activity [30.23% (19.09) versus 12.97% (25.12) were also found in the DASH group. ConclusionsThe DASH diet could improve weight loss, BMI and fat mass. Furthermore, it could result in a significant reduction in serum androstenedione and a significant increase in antioxidant status and SHBG.