Fecal Microbiota Transplantation by Rectal Enema Improves Short-Term Insulin Resistance in Metabolic Syndrome: A Pilot Randomized Controlled Trial.

BACKGROUND

The gut microbiota plays a vital role in various physiological processes, including metabolism. Fecal microbiota transplantation (FMT) involves transferring fecal matter from a healthy donor to rebalance a patient's intestinal dysbiosis. The impact of FMT on metabolic syndrome (MetS) is subject to debate. This study assesses the effects of FMT on MetS when administered by rectal enema.

METHODS

In a double-blind, randomized controlled trial, subjects with MetS were assigned to receive either FMT (n=8) or a sham intervention (n=10) via rectal enema. Participants were followed at 6 and 12 weeks. The primary outcome was changes in the homeostatic model assessment of insulin resistance (HOMA-IR). Secondary outcomes included fasting blood glucose (FBG), body mass index (BMI), inflammatory markers, and hepatic steatosis. The mean adjusted difference (MAD) and 95% confidence interval (CI) between groups were reported as treatment effects using a linear marginal model for repeated measures.

RESULTS

The study included patients with a mean age of 50.4±10.7 years. Baseline BMI and HOMA-IR were similar between groups. Over 6 weeks, FMT significantly improved HOMA-IR (MAD, -1.63; 95% CI, -2.63 to -0.64; P=0.001). The FMT group also showed improvements in serum FBG and high-sensitivity C-reactive protein compared with levels in the sham group (P=0.044 and P=0.025, respectively). However, no significant changes in MetS-associated variables or liver steatosis were evident at 12 weeks. Stool microbiota analysis revealed a reduced relative abundance of Desulfovibrio, Bacteroides, and Parabacteroides after FMT.

CONCLUSION

FMT by rectal enema produced favorable changes in IR in patients with MetS. FMT may be an effective treatment for patients with metabolism-related diseases. Further research into the long-term benefits of the procedure is warranted.