The Effects of Six Months Supplementation with Probiotics and Synbiotic on Gut Microbiota in the Adults with Prediabetes: A Double-Blind Randomized Clinical Trial

Introduction: The evidences of 16S rRNA genes in the gut microbiota distinguished a higher Firmicutes/Bacteroidetes ratio in the obese and diabetic individuals compared to healthy ones. So, it seems that the modulation of intestinal microbial ecology by pro/pre/synbiotics may contribute to the progression and prevention of metabolic diseases. This study was performed to assess the effects of probiotics and synbiotic supplementation on intestinal microbiome modifying in adults with prediabetes.Methods: In a randomized, double-blinded, placebo-controlled clinical trial, 120 patients with prediabetes were randomly assigned to consume 6 g/d either a placebo containing maltodextrin (control) or multispecies probiotic or inulin-based synbiotic for 6 months. Fecal samples were obtained at baseline and after 6 months supplementation. Dietary intake was assessed throughout the study (at baseline and after 3 and 6 months). Total energy, macronutrients and dietary fiber were calculated using a dietary programed Nutritionist 4. DNA was extracted from fecal samples and the numbers of Clostridium perfringens (the represent of phylum Firmicutes), Bacteroides fragilis (the representative of Bacteroidets) and Escherichia coli (as universal bacteria) were determined by quantitative real-time polymerase chain reactions (qPCR). The changes in relative abundance of the two fecal bacteria before and after supplementation were analyzed and compared within and between groups.Results: There were no significant changes in dietary intakes during the study. Six months’ supplementation with probiotic resulted in statistically significant increase in abundance of Bacteroides fragilis to E.coli ratio (MD±SE:0.47±0.37, p=0.04) and decrease of relative proportion of Firmicutes to Bacteroidetes representatives (MD±SE:-118.8±114.6, p=0.02). Synbiotic had no significant effect on the changes of the bacteria. There were no significant differences between the three groups.Conclusion: The results of this study suggest that manipulation of the human gut microbiome by using probiotics could provide a potential therapeutic approach in the prevention and management of obesity and type-2-diabetes.