Functional gastrointestinal disorders : digestive symptoms

The microbiota of patients with irritable bowel syndrome is less diversified and shows greater abundance of enterobacteria, but with a lower content in bifidobacteria and lactobacilli. Functional gastrointestinal disorders are characterized by a decreased production of butyrate and an increased production of acetic and propionic acids, which are three substances associated with bloating. Abdominal pain, diarrhea and constipation are other symptoms of these disorders. In the US, an estimated 20% of the population is affected¹⁴.

Controversial effects

Aside from ulcerative colitis, irritable bowel syndrome is the only other gastrointestinal condition for which a treatment with fecal microbiota transplant has been studied in clinical trials¹⁴. One of them showed a decrease in intestinal discomfort, abdominal pain and flatulence in transplant recipients. However, the results varied depending on the initial nature of the gut microbiota: the best responders to fecal microbiota transplant had an initial high content of Streptococci and they had a greater increase in biodiversity. Other works confirm the increased diversity and abundance of the microbiota after the administration of fecal matter capsules; however, patients reported a better improvement in symptoms when they received... placebo! Although these results do not undermine the efficacy of FMT in people with functional gastrointestinal disorders, detailed microbiota analyses before and after the transplant are necessary, according to the researchers.

What about constipation?

Constipation is potentially associated to gut dysbiosis and has been the focus of several works aiming at assessing the usefulness of FMT in this transit disorder¹³. In a study conducted in about sixty adults suffering from slow transit that compared the standard treatment to 6 courses of FMT, the latter was shown to cause a significant improvement of symptoms and transit, and more generally, in the quality of life¹⁵. These encouraging results still need to be confirmed: studies are also ongoing with specific strains, lactobacilli and bifidobacteria¹³.