Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 54 7 2025 07 08 1540 1550 EN Zahra Hariri Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran Zahra Yari Department of Nutrition Research, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maryam Nilghaz Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran Monirsadat Mirhoseini Department of Cellular and Molecular Nutrition, Faculty of Nutrition and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sedighe Hoseini Department of Obstetrics and Gynecology, Preventative Gynecology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Khadijeh Abhari Department of Food Science and Technology, National Nutrition and Food Technology Research Institute, Faculty of Nutri-tion Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran Golbon Sohrab Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2023 08 27 2023 11 07 Background: We aimed to investigate the effect of synbiotic supplement-containing spore-forming Bacillus coagulans (GBI-30) on the glycemic, hormonal and anthropometric parameters in patients with PCOS. Methods: In this randomized, triple-blind, placebo-controlled trial, 72 patients with PCOS were randomly and equally assigned to receive a daily sachet of synbiotic (containing Bacillus coagulans (GBI-30), Lactobacillus rhamnosus, Lactobacillus helveticus, and fructooligosaccharide (FOS)) or placebo for 12 wk. Glycemic, hormonal and anthropometric parameters were measured at baseline and after the 12-week of intervention. Results: At the end, 60 patients completed the study. After adjustment for potential confounders, significant decrease in insulin (−3.38±20.20 vs. +2.33, P=0.042), homeostatic model assessment for insulin resistance (HOMA-IR) (−0.43±3.61 vs. +0.73 ± 2.91, P=0.044) and dehydroepiandrosterone sulfate (DHEAS) (−1.47±6.62 vs. + 0.03 ± 2.06, P=0.047) was observed in the intervention group compared to the control group. Supplementation with synbiotic failed to show a significant effect on anthropometric parameters and fasting blood sugar. Conclusion: Overall, 12 wk supplementation with synbiotic-containing Bacillus coagulans (GBI-30) can offer additional benefit to lifestyle intervention on metabolic status of women with polycystic ovarian syndrome. https://ijph.tums.ac.ir/index.php/ijph/article/view/33025 https://ijph.tums.ac.ir/index.php/ijph/article/download/33025/8608