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Ulcerative colitis

A long-term inflammatory bowel disease of the lining of the colon and rectum.

Compared within 7 studies that had both: 820 people with ulcerative colitis and 624 healthy people. 134 microbes are less common in people with ulcerative colitis, and 28 more common.

A difference is an association: it doesn’t mean these microbes cause, prevent or treat ulcerative colitis.

Phylum

Searching opens both lists and shows only matching rows.

Less common in ulcerative colitis · 134

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Gallintestinimicrobium propionicum in 7 studies Healthy 75% ulcerative colitis 36%
  2. Gemmiger formicilis in 7 studies Healthy 65% ulcerative colitis 28%
  3. Clostridium sp. AM49-4BH in 7 studies Healthy 45% ulcerative colitis 16%
  4. Clostridiaceae bacterium Marseille-Q4143 in 7 studies Healthy 49% ulcerative colitis 21%
  5. Oscillibacter sp. MSJ-31 in 7 studies Healthy 42% ulcerative colitis 15%

More common in ulcerative colitis · 28

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Anaerococcus obesiensis in 7 studies Healthy 0% ulcerative colitis 4.6%
  2. Thomasclavelia ramosa in 7 studies Healthy 15% ulcerative colitis 30%
  3. [Clostridium] symbiosum in 7 studies Healthy 23% ulcerative colitis 39%
  4. Dialister pneumosintes in 7 studies Healthy under 1% ulcerative colitis 5.5%
  5. Gemella morbillorum in 7 studies Healthy under 1% ulcerative colitis 3.3%

Where these numbers come from

Studies
Only GMrepo projects that had people with the condition and healthy people, 10 or more of each. Numbers come from those studies, never from pooling.Sampled in China, Germany, India, Ireland, the United States.
How common
The share of people whose sample has any of it, in the people with the condition and in the healthy people of those same studies. Tested within studies (Cochran–Mantel–Haenszel, corrected for testing many microbes); a difference counts when it is clear and meaningful (Cohen’s h of 0.2 or more).
Strength word
Counted by code from how many studies point the same way: Seen again and again (3 or more, none clearly the other way), Seen more than once (2, the majority), Seen once (1, listed last). Where studies disagree, a row isn’t listed.
Each study
Tap a row for every study’s own numbers, and for how much carriers have.
Analysis
Our analysis of GMrepo data. GMrepo on Data sources · Read the rules

Also compared · 438 microbes

Compared within studies that had both, but not listed above.

Studies disagree · 24

No meaningful difference · 414
PubMed · human studies and reviews first

Recent research

All research on it
  1. Review Frontiers in immunology · 2026
    Research progress on intestinal probiotics-mediated protection of the intestinal mucosal barrier in ulcerative colitis.
    PubMed ↗
  2. Randomized trial mSystems · 2026
    Sialidase inhibitor modulates gut microbiota and enhances mucosal protection in the treatment of ulcerative colitis.
    PubMed ↗
  3. Review Molecular biology reports · 2025
    The gut immune axis in ulcerative colitis: insights from microbiome research.
    PubMed ↗
  4. Observational Gastroenterology · 2025
    Structural Variations in Ulcerative Colitis-associated Escherichia coli Reduce Fructose Utilization and Aggravate Inflammation Under High-Fructose Diet.
    PubMed ↗
  5. Observational Nature communications · 2024
    Multi-biome analysis identifies distinct gut microbial signatures and their crosstalk in ulcerative colitis and Crohn's disease.
    PubMed ↗

Source: PubMed, U.S. National Library of Medicine · 259 linked papers, last 10 years