Fecal transplant (FMT) for ulcerative colitis

Development of the therapy

The first signal that FMT might help UC came from case reports in the 2000s. Four subsequent randomised trials — Moayyedi 2015 (Canada), Rossen 2015 (Netherlands), Paramsothy 2017 (Sydney FOCUS trial), and Costello 2019 — collectively established that intensive, multi-donor FMT is more effective than placebo at inducing clinical remission, with absolute benefits in the range of 15–25 percentage points.¹²

Therapeutic target

Patients with UC have reduced microbial diversity, depletion of butyrate-producing Firmicutes (notably Faecalibacterium prausnitzii), and expansion of pro-inflammatory taxa. FMT is hypothesised to dampen mucosal inflammation by restoring short-chain fatty acid production, reinforcing the colonic mucus layer, and modulating regulatory T-cell responses.³ A consistent finding across trials is a donor effect: a small number of "super-donors" account for most responses.

What the trials show

• Induction of remission in roughly 25–30% of FMT recipients vs ~5–10% of placebo recipients across the four RCTs.
• Intensity matters: protocols using multiple infusions per week from pooled donors outperform single-dose protocols.
• Maintenance remains an open question — most trials only treat for 6–8 weeks, and durable remission beyond a year is less well characterised.
• FMT has not been directly compared head-to-head with anti-TNF biologics, vedolizumab, or JAK inhibitors.

Possible side effects and risks

• Transient flare of GI symptoms — bloating, cramping, increased stool frequency — in the first days after treatment
• Rare reports of self-limited fever and transient bacteraemia
• Concern that FMT could trigger a flare in some patients, though this has not been borne out in the controlled trials
• The same long-term microbiome-modification uncertainty that applies to all FMT

FAQ: FMT in ulcerative colitis

The decision to try FMT for UC is individualised and should be made with a gastroenterologist familiar with current trial data.

References

1. Paramsothy S, et al. Multidonor intensive faecal microbiota transplantation for active ulcerative colitis: a randomised placebo-controlled trial. Lancet. 2017.
2. Costello SP, et al. Effect of fecal microbiota transplantation on 8-week remission in patients with ulcerative colitis: a randomized clinical trial. JAMA. 2019.
3. Lopez J, Grinspan A. Fecal microbiota transplantation for inflammatory bowel disease. Gastroenterol Hepatol (NY). 2016.