Fecal transplant: “where, when, how much” needed to optimize effects on IBS?
What is the best combination of factors for fecal transplantation as a treatment for irritable bowel syndrome (IBS)? According to Norwegian researchers and clinicians, a transplant dose of between 60 g and 90 g into the small intestine, rather than the colon, and ideally repeated.
About this article
Between 2015 and 2020, fecal microbiota transplant (FMT) as a treatment for irritable bowel syndrome (IBS) was tested in seven randomized controlled trials (RCTs). The outcomes of these RCTs varied considerably, probably due to differences in the protocols used. A Norwegian team studied the effects of FMT dose, repetition, and area of administration, using the same protocol as in their previous RCT, which saw very good results (long-standing effects up to three years after FMT, with only a few mild adverse effects). The transplant came from the same (sidenote: Super-donor A donor with high microbial diversity, whose microbiota quality conditions FMT results. In this case, a healthy, non-smoking 40-year-old Caucasian male born vaginally, breastfed, who had taken only a few courses of antibiotics during his life, took no medication regularly, had a normal BMI, exercised regularly, and took sport-specific dietary supplements (which made his diet richer than average in protein, fiber, minerals, and vitamins). ) .
Symptoms improved with repeated FMT
This new study included 186 patients suffering from irritable bowel syndrome, randomized into three groups receiving a 90 g fecal transplant (versus 30 g or 60 g in the previous RCT) either to the colon, to the duodenum, or twice to the duodenum with a one-week interval.
In the year following the FMT, the researchers observed a much lower prevalence of (sidenote: Assessed using the IBS-SSS, the Birmingham IBS Symptom Questionnaire (BSQ) and the Fatigue Assessment Scale (FAS). ) , regardless of the group and the time elapsed since FMT: present in 75% of patients on the day of transplantation, they affected 17%-32% (depending on the group) after 3 months, and 24%-41% after one year. Similarly, (sidenote: Assessed using the IBS Quality of Life Instrument (IBS-QoL) and Short-Form Nepean Dyspepsia Index (SF-NDI) questionnaire. ) improved in all three groups, regardless of the time elapsed since FMT. Moreover, repeating transplantation improved the beneficial effects on symptoms and quality of life.
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Favoring the small intestine over the colon
An analysis of fecal samples (16s rRNA) taken at baseline and at 3, 6, and 12 months after FMT showed a significant reduction in dysbiosis in all treatment groups. Bacterial profiles changed considerably following FMT for all three groups and at all observation dates, with differences between the groups. These changes notably concerned six bacteria linked to symptoms and fatigue, such as Alistipes spp., implicated in several diseases such as depression, anxiety, and chronic fatigue syndrome, or Holdemanella biformis, which has anti-inflammatory effects.
Transplanting into the small intestine enables the colonization of beneficial bacteria over the long term, unlike transplanting into the colon, where the effect appears to be more transient. Conversely, while the beneficial effect increased with dose in the previous RCT (greater effect at 60 g than at 30 g), the 90 g dose has no additional benefit compared with the 60 g already tested: the optimal dose would therefore be between 60 g and 90 g.