Fecal microbiota transplantation improves metabolic syndrome parameters: systematic review with meta-analysis based on randomized clinical trials

Obesity and metabolic syndrome are important health problems that can lead to significant morbidity/mortality as well as subsequent health concerns. Alterations in the gut microbiota have been implicated in both obesity and metabolic syndrome. Fecal Microbiota Transplantation (FMT) has emerged as a new promising therapeutic approach aimed at manipulating the gut microbiota in various chronic diseases. Randomized clinical trials assessing the use of FMT in obese and metabolic syndrome patients have been reported. The purpose of this systematic review with meta-analysis using randomized clinical trials (RCT) is to evaluate the role of FMT for the treatment of obesity and metabolic syndrome and its impact on clinically relevant parameters. We searched the main databases, as well as the gray literature, to identify RCTs comparing FMT from lean donor(s) vs placebo for obese/metabolic syndrome patients. We included all studies that utilized any form of placebo (sham, saline, autologous FMT, or placebo capsules). Six studies met the inclusion criteria and were included for final analysis with a total of 154 patients. We looked for clinically significant parameters related to obesity and metabolic syndrome and organized the findings into early (2-6 weeks after intervention) and late (12 weeks after intervention) outcomes. Two to 6 weeks after intervention, mean HbA1c was lower in the FMT group (MD = -1.69 mmol/L, CI -2.88, -0.56, P = .003) and mean HDL cholesterol was higher in the FMT group (MD = 0.09 mmol/L, CI 0.02, 0.15, P = .008). There was no difference in obesity parameters 6 to 12 weeks after intervention. No serious adverse events were reported. The findings for this meta-analysis show that FMT may have a role for the treatment of metabolic syndrome, but there is currently not enough evidence to support its use in clinical practice. High-quality well-powered RCTS with longer follow-up are necessary to clarify the role of FMT in this patient cohort.