The effect of synbiotic on glycemic profile and sex hormones in overweight and obese breast cancer survivors following a weight-loss diet: A randomized, triple-blind, controlled trial

Summary Background The investigation was designed to assess the effects of synbiotic supplementation on glycemic profile, insulin-like growth factor-1 (IGF-1) and sex hormones in overweight and obese postmenopausal breast cancer survivors (BCSs) who had hormone-receptor-positive breast cancer. Methods This randomized, triple-blind, placebo-controlled trial was conducted on 76 overweight and obese BCSs aged 57.43 (5.82) years. All participants were given a specified low calorie diet and were randomly assigned into two groups to intake 109 CFU/day of synbiotic supplement (n = 38) or placebo (n = 38) for 8 weeks. Body composition, physical activity, glycemic profile, IGF-1, estradiol, testosterone and dehydroepiandrosterone sulfate (DHEA-S) were measured at baseline and after 8 weeks. Results A significant reduction in serum insulin (median change (Q1, Q3) from baseline of −1.05 (−2.36, 0.32) μIU/mL; P = 0.006) and insulin resistance (HOMA-IR) (mean change (SD) from baseline of −4.0 (0.9); P = 0.007) were seen over the 8 weeks in the synbiotic group. However, no significant changes were observed in serum insulin, fasting plasma glucose, HbA1c, HOMA-IR, IGF-1, estradiol, testosterone, DHEA-S and sex hormone binding globulin between-groups at the end of the intervention. Conclusions Overall, as the 8-week synbiotic consumption compared with placebo had insignificant-reducing effects on glycemic profile, IGF-1 and sex hormones among overweight and obese postmenopausal BCSs, synbiotics may exert considerable beneficial consequences, which need to be further assessed in future clinical trials. Trial registration IRCT, IRCT2015090223861N1. Registered 02 February 2017, http://www.irct.ir : IRCT2015090223861N1.