Volume 30, Issue 169, March 2026

Rheumatoid Arthritis and the Gut Microbiota: Findings from Recent Studies (2017-2025)

Wiktoria Polkowska^1♦, Maja Kondratowicz², Kamila Kałamarz³, Kinga Żmuda⁴, Maciej Świerczyna⁵, Maja Czerniachowska⁶, Marcin Kaniewski⁷, Martyna Wojnowska⁸, Aleksandra Figzał⁹, Michał Grabek¹⁰

¹Central Clinical Hospital, Medical University of Łódź, Pomorska 251, 90-213 Łódź, Poland
²The Independent Public Hospital No. 4, Doktora Kazimierza Jaczewskiego 8, 20-954 Lublin, Poland
³Karol Marcinkowski University Hospital, Zyty 26, 65-046 Zielona Góra, Poland
⁴University Clinical Hospital of Opole al.W.Witosa 26 45-401 Opole, Poland
⁵Ministry of the Interior and Administration Hospital, Północna 42, 91-425 Łódź, Poland
⁶Medical University of Łódź, al. Kościuszki 4, 90-419 Łódź, Poland
⁷The Independent Public Hospital No. 4, Doktora Kazimierza Jaczewskiego 8, 20-954 Lublin, Poland
⁸Mikolaj Pirogov Provincial Specialist Hospital, Wólczańska 191/195, 90-001 Łódź, Poland
⁹Karol Marcinkowski University Hospital, Zyty 26, 65-046 Zielona Góra, Poland
¹⁰Karol Marcinkowski University Hospital, Zyty 26, 65-046 Zielona Góra, Poland

^♦Corresponding author
Wiktoria Polkowska, Central Clinical Hospital, Medical University of Łódź, Pomorska 251, 92-213 Łódź, Poland

ABSTRACT

Rheumatoid arthritis (RA) is one of the most common autoimmune conditions, characterized by persistent joint inflammation. Recent studies have examined the gut microbiota in patients with RA and in individuals assessed before clinical symptoms appear. This review provides an overview of recent findings on alterations in gut microbiota in rheumatoid arthritis. Many studies report lower bacterial diversity and reduced numbers of short-chain fatty acid-producing bacteria compared with healthy individuals. Similar findings are also observed in some individuals before the onset of clinical disease. The review also discusses factors influencing gut microbiota composition, such as diet, antibiotic use, and genetic background, and reviews studies evaluating probiotic supplementation. Differences in gut microbiota are observed in individuals carrying HLA-DRB1 risk alleles. Some studies also report a poorer response to methotrexate in patients with lower bacterial diversity and fewer short-chain fatty acid-producing bacteria. Gut microbiota changes are common in RA, but they vary among patients. At this stage, this evidence helps explain disease mechanisms but has limited use in routine clinical practice.

Keywords: rheumatoid arthritis; gut microbiota; dysbiosis; short-chain fatty acids; intestinal barrier; probiotics

Medical Science, 2026, 30, e57ms3811

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DOI: https://doi.org/10.54905/disssi.v30i169.e57ms3811

Published: 18 March 2026