A Pill Could Replace Colonoscopy for Crohn’s Microbiome Therapy, Trial Finds

Patients with Crohn's disease who undergo surgery to remove the ileocecal region face a frustrating reality: the disease often returns in the same area, and the gut microbiome is thought to play a central role in that recurrence. A new pilot randomized trial published in Inflammatory Bowel Diseases by Moutsoglou D and colleagues now suggests that microbiota transplant therapy (MTT), also known as fecal microbiota transplantation or FMT, can be delivered either by colonoscopy or by oral capsule with comparable results in stool and the neoterminal ileum, the bowel segment most vulnerable to recurrence.

Oral capsules and colonoscopy produce similar FMT engraftment in Crohn's patients

The core result is straightforward: at eight weeks, both delivery methods produced statistically similar levels of donor microbiome engraftment, whether measured in stool samples or in biopsies taken from the neoterminal ileal mucosa. Engraftment, in this context, refers to how much of the donor's microbial community has taken up residence in the recipient's gut. Alpha diversity (the variety of species within a single sample) and beta diversity (how much the microbial community differs between samples) both differed significantly between baseline neoterminal ileum and stool, confirming that the two compartments harbor distinct microbial landscapes. Crucially, though, stool and ileal engraftment levels were significantly correlated with each other, suggesting that the easier-to-obtain stool sample may reliably reflect what is happening deeper in the bowel wall.

This finding echoes earlier work in C. difficile infection showing oral capsule FMT was noninferior to colonoscopy delivery for preventing recurrence over 12 weeks, with fewer minor adverse events for the capsule group. Seeing a similar pattern emerge in Crohn's disease broadens the potential scope of the capsule approach.

Why delivery route matters for postoperative Crohn's disease management

Ileocecal resection is one of the most common surgical procedures for Crohn's disease, and roughly half of patients develop endoscopic recurrence within a year of surgery. Microbiota transplant therapy is an emerging intervention in inflammatory bowel disease more broadly: randomized controlled trials of FMT in IBD have shown significant effects on clinical remission compared to placebo, though optimal administration routes and donor selection remain open questions. If oral capsules can match colonoscopy for engraftment, that matters practically. Colonoscopy requires bowel preparation, sedation, and a specialist procedure suite. Capsules can be taken at home, potentially making therapy more accessible and enabling earlier treatment in the postoperative window, before recurrence takes hold.

Beyond convenience, the trial also reported a significant reduction in CD symptoms as measured by the Harvey-Bradshaw Index across the full 16-week follow-up period. No differences in symptom improvement were found between the two delivery routes. Oral MTT was described as well tolerated.

How the trial was designed and what it measured

Moutsoglou and colleagues conducted a single-blind, pilot randomized trial registered as NCT05248191. Participants all had a history of ileocecal resection for Crohn's disease and underwent a baseline colonoscopy before randomization. The 1:1 allocation assigned one group to a single liquid MTT delivered via colonoscopy during that initial scope, and the other group to five days of encapsulated, lyophilized oral MTT capsules. Lyophilization (freeze-drying) is a processing method that allows the microbial preparation to be stored and swallowed without refrigeration chains required for liquid preparations.

At week 8, all participants underwent a follow-up ileocolonoscopy with biopsies, providing the mucosal engraftment data that forms the study's primary microbiome readout. Clinical assessments using the Harvey-Bradshaw Index continued through week 16. The single-blind design means participants knew which treatment they received but assessors were blinded, a reasonable compromise given that blinding to colonoscopy versus capsules is practically difficult.

The engraftment-to-clinical-outcomes gap remains unresolved

One of the more thought-provoking findings is what the trial did not show. Despite similar engraftment across both arms and a significant overall reduction in symptoms, donor engraftment levels did not correlate with individual clinical outcomes. This is a recurring puzzle in FMT research: achieving measurable colonization by donor microbes does not reliably predict whether a patient will feel better. It raises questions about which specific microbial taxa drive therapeutic benefit, whether the timing of measurement matters, and whether the heterogeneity in donor selection introduces confounding that obscures dose-response relationships.

As a pilot study, the trial was not powered to answer those questions, and the single-blind design means some participant behavior differences between arms cannot be ruled out. FMT research more broadly is still working out how to optimize donor selection, standardize stool processing, and match delivery methods to specific conditions, and IBD sits at the more complex end of that challenge compared to C. difficile infection, where FMT's track record is more established.

Next steps for oral MTT and postoperative Crohn's trials

The authors identify one clear priority for follow-up: evaluating oral administration earlier in the postoperative disease course, before mucosal recurrence has had time to establish. The current trial enrolled patients at an unspecified point after resection; intervening in the immediate postoperative window, when the gut microbiome is presumably most amenable to reseeding, could yield stronger effects. The broader FMT field is moving toward FDA-approved standardized products, with agents like Rebyota and Vowst now available for C. difficile, and investigational agents targeting other conditions are advancing, suggesting that a regulatory pathway for IBD-specific formulations is plausible if larger trials confirm efficacy.

For now, this pilot supports a pragmatic next step: designing a larger, adequately powered trial using oral capsules as the comparator arm, with engraftment and clinical remission as co-primary endpoints. The finding that stool engraftment correlates with ileal engraftment is also a practical bonus, potentially reducing the need for surveillance colonoscopies purely for microbiome monitoring in future studies.

Evidence rating

EMERGING — 78/100

Caveats:

• Pilot trial — sample size was small, limiting statistical power to detect differences in clinical outcomes.
• Single-blind design: participants knew which treatment arm they were in, introducing potential placebo effects especially for symptom-based outcomes.
• Donor engraftment did not correlate with clinical improvement, meaning the mechanism linking MTT to symptom reduction remains unclear.
• No control (sham) arm was included, so the observed symptom reduction cannot be attributed to MTT alone.
• Funding was not disclosed; the independence of this research cannot be fully assessed.
• Results have not yet been independently replicated in a larger trial.

Single-blind pilot randomized trial comparing two routes of microbiota transplant delivery in postoperative Crohn's disease patients. The study demonstrates equivalent engraftment by both routes but cannot establish causation for the observed symptom reduction, which was measured without a sham control group. Results await replication in a larger, adequately powered trial.

References

1. Daphne Moutsoglou, Christopher Staley, Amanda J Kabage, Alexander Khoruts, Byron P Vaughn (2026). Colonoscopic and oral microbiota transplant therapy yield similar stool and neoterminal ileal engraftment profiles in a single-blind pilot randomized trial. Inflammatory Bowel Diseases. https://doi.org/10.1093/ibd/izag096
2. Dina Kao, Brandi Roach, Marisela Silva, et al. (2017). Effect of Oral Capsule– vs Colonoscopy-Delivered Fecal Microbiota Transplantation on Recurrent Clostridium difficile Infection. JAMA. https://doi.org/10.1001/jama.2017.17077
3. A Systematic Review and Meta-Analysis of Randomized Controlled Trials of Fecal Microbiota Transplantation for the Treatment of Inflammatory Bowel Disease – PMC. NIH. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9347895/
4. Fecal microbiota transplantation: present and future – PMC – NIH. NIH. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10055725/
5. Fecal microbiota transplantation: Current evidence and future directions – PubMed. NIH. https://pubmed.ncbi.nlm.nih.gov/40592538/
6. What's New and What's Next in Fecal Microbiota Transplantation? – PMC – NIH. NIH. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10444585/