Fecal microbiota transplantation in patients with irritable bowel syndrome: an overview of current studies

As dysbiosis is a key factor associated with irritable bowel syndrome (IBS), modulation of the intestinal microbiota could improve IBS symptoms and quality of life. Fecal microbiota transplantation (FMT) could be one efficient way to restore bacterial composition in IBS patients. This review comprises 12 clinical trials published from 2017 to 2021. Inclusion criteria were the assessment of IBS symptoms using the IBS symptom severity score, quality of life measured by the lBS quality of life scale, and gut microbiota analysis. Improved symptoms were reported in all 12 studies, paralleling with an increased quality of life after FMT, but also partly after placebo treatment. The use of oral capsules showed that the placebo treatment can have similar or even stronger positive effects on IBS patients than FMT. Gastroscopic FMT appears to link modulation of the gut microbiome to significant symptom reduction in patients. The patient's microbiota profile shifted toward their respective donors. Symptom worsening or decreased quality of life after FMT was not reported. The results show that FMT could be a therapeutic approach in IBS patients. Further research is needed to investigate whether FMT has a more beneficial effect on IBS patient than placebo treatment with the patient's own stool, placebo capsules, or bowel cleansing. Moreover, optimal donor selection, frequency, dosage, and route of delivery still need to be defined.