Effects of legume-based DASH diet on anthropometric factors, glucose/lipid profiles and free testosterone level in women with polycystic ovary syndrome (PCOS): a randomized clinical trial

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder in women of reproductive age, strongly associated with metabolic dysfunction, particularly insulin resistance. Dietary strategies such as the Dietary Approaches to Stop Hypertension (DASH) diet may offer therapeutic benefits, while legume enrichment may enhance its metabolic effects. This study aimed to evaluate the effects of a legume-based DASH diet on anthropometric, glycemic, lipid, and hormonal parameters in women with PCOS. This randomized controlled clinical trial was conducted among 54 women with PCOS aged 20–50 years in Yazd, Iran. Participants were randomly assigned to a legume-based DASH diet or a control diet for 16 weeks. Of the randomized participants, 47 completed the study (intervention: 25; control: 22). Both groups received comparable calorie-restricted diets with a 500–700 kcal/day energy deficit, while differing in dietary pattern and macronutrient composition. Between-group differences in post-intervention outcomes were assessed using analysis of covariance (ANCOVA), adjusting for baseline values, changes in total energy intake, and physical activity. All analyses were conducted according to the intention-to-treat principle, with multiple imputation used to address missing data. Compared with the control diet, the legume-based DASH diet significantly improved weight ( P = 0.02; partial η² = 0.11), waist circumference ( P = 0.02; partial η² = 0.10), hip circumference ( P = 0.03; partial η² = 0.09), and menstrual cycle duration ( P = 0.02; partial η² = 0.098), and favorably altered high-density lipoprotein cholesterol (HDL-C) ( P = 0.04; partial η² = 0.085) and low-density lipoprotein cholesterol (LDL-C) ( P = 0.006; partial η² = 0.14) after adjustment for baseline values, energy intake, and physical activity; however, no significant adjusted between-group differences were observed for fasting blood sugar (FBS), insulin, homeostatic model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), triglycerides, total cholesterol, or free testosterone. A legume-based DASH dietary pattern may improve anthropometric measures, menstrual cycle duration, and selected lipid parameters, particularly HDL-C and LDL-C, in women with PCOS and overweight or obesity. However, the intervention did not significantly improve HOMA-IR, the prespecified primary outcome, or other glycemic indices and free testosterone over 16 weeks. Iranian Registry of Clinical Trials (IRCT20120913010826N33), registered on June 12, 2023.