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Rheumatoid arthritis

Compared within 2 studies that had both: 121 people with rheumatoid arthritis and 94 healthy people. 2 microbes are less common in people with rheumatoid arthritis, and 6 more common.

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

Phylum

Searching opens both lists and shows only matching rows.

Less common in rheumatoid arthritis · 2

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Streptococcus parasanguinis in 2 studies Healthy 37% rheumatoid arthritis 19%
  2. Wujia chipingensis in 2 studies Healthy 46% rheumatoid arthritis 27%

More common in rheumatoid arthritis · 6

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Prevotella marseillensis in 2 studies Healthy 3.3% rheumatoid arthritis 19%
  2. Roseburia inulinivorans in 2 studies Healthy 75% rheumatoid arthritis 93%
  3. Lachnospira pectinoschiza in 2 studies Healthy 81% rheumatoid arthritis 95%
  4. Clostridium perfringens in 2 studies Healthy 9.7% rheumatoid arthritis 24%
  5. Lachnospiraceae bacterium OF09-6 in 2 studies Healthy 9.7% rheumatoid arthritis 22%

As many carry these · 1 the amount differs

Strongest first, then the biggest gap · Each figure is 10 people Strongest first · Each figure is 10 people
  1. Agathobaculum butyriciproducens in 2 studies Healthy 87% rheumatoid arthritis 91%

    Carriers have about twice as much, in 2 of 2 studies (0.14% → 0.26% of their gut microbes).

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.
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 · 349 microbes

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

Studies disagree · 7

No meaningful difference · 342
PubMed · human studies and reviews first

Recent research

All research on it
  1. Observational International journal of rheumatic diseases · 2026
    Integrated Analysis of Gut Microbiota and Fecal Metabolites in Chinese Patients With Rheumatoid Arthritis: Associations With Disease Activity.
    PubMed ↗
  2. Systematic review The Journal of rheumatology · 2026
    Gut Microbiota as a Biomarker and Target in Biologic Therapy for Autoimmune and Immune-Mediated Arthritis: A Systematic Review.
    PubMed ↗
  3. Review Frontiers in immunology · 2026
    Mechanistic insights into gut microbiota-driven autoimmunity in rheumatoid arthritis.
    PubMed ↗
  4. Randomized trial Journal of infection in developing countries · 2025
    Therapeutical efficacy of immunobiotics in patients with newly diagnosed rheumatoid arthritis.
    PubMed ↗
  5. Review The Journal of clinical investigation · 2025
    Microbial threads in the tapestry of rheumatoid arthritis.
    PubMed ↗

Source: PubMed, U.S. National Library of Medicine · 57 linked papers, last 10 years