Volume 30, Issue 171, May 2026

The Role of Gut Microbiota in the Development of Depression: A Review

Adam Brożyna¹, Agnieszka Mackiewicz^2♦, Aleksandra Pietrucień³, Natalia Kursa⁴, Katarzyna Bielak⁵, Krystian Woźniak⁶, Julia Witkowska⁷, Ksenia Jakubiak⁸, Mikołaj Kurczyński⁹, Monika Krasoń¹⁰

¹University Clinical Hospital No. 1 of the Medical University of Lodz: Łódź, 90-153, ul. Kopcińskiego 22, PL
²Medical Centre of Pabianice, Pabianice, 95-200, ul. Jana Pawła II 68, PL
³Medical Centre of Pabianice, Pabianice, 95-200, ul. Jana Pawła II 68, PL
⁴Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁵Military Clinical Hospital in Cracow, 30-901 Cracow, ul. Wrocławska 1-3, PL
⁶Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁷University Clinical Hospital No. 1 of the Medical University of Lodz: Łódź, 90-153, ul. Kopcińskiego 22, PL
⁸Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
⁹Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL
¹⁰Central Teaching Hospital of The Medical University of Lodz: Łódź, 92-213, ul. Pomorska 251, PL

^♦Corresponding author
Agnieszka Mackiewicz, Medical Centre of Pabianice, Pabianice, 95-200, ul. Jana Pawła II 68, PL

ABSTRACT

Depression is a common disorder, but we still do not understand its exact pathogenesis. In recent years, the interest in the role of gut microbiota has increased. The microbiota–gut–brain axis describes the connection between the gastrointestinal system and the central nervous system, involving neural, immune, and metabolic pathways. This review aims to present current knowledge on this relationship. Research has shown that patients with major depressive disorder (MDD) have a distinct gut microbiota structure compared to healthy individuals. Similar observations come from animal studies. Researchers observed that transplantation of microbiota from depressed individuals may induce depressivelike behavior in experimental models. Several mechanisms may explain this association. These include increased inflammatory activity, disturbances in tryptophan metabolism, and changes in neuroendocrine function. There are also studies suggesting that modifying the gut microbiota, for example, with probiotics or fecal microbiota transplantation, may have a positive effect on depressive symptoms. In conclusion, current data suggest that gut microbiota may play a role in depression. However, further studies are needed to understand these mechanisms better and to evaluate their possible clinical use.

Keywords: gut microbiota, depression, major depressive disorder, gut-brain axis, and inflammation.

Medical Science, 2026, 30, e93ms3880

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DOI: https://doi.org/10.54905/disssi.v30i171.e93ms3880

Published: 29 May 2026