Gut microbiota-supportive dietary patterns and rheumatoid arthritis: the mediating role of the systemic...

Background: the gut microbiota has emerged as a potential contributor to autoimmune diseases, including rheumatoid arthritis (RA), through its role in modulating systemic inflammation. However, few studies have evaluated whether adherence to microbiota-supportive dietary patterns is associated with RA in population-based settings. Methods: this study analyzed data from 21.352 adults in the 2010-2020 cycles of the National Health and Nutrition Examination Survey (NHANES). The Dietary Index for Gut Microbiota (DI-GM), ranging from 0 to 14, was used to quantify the extent to which habitual diets support gut microbial health. Logistic regression and restricted cubic spline models were used to examine the association between DI-GM and RA. Mediation analysis was conducted to evaluate whether the systemic immune-inflammation index (SII) mediated this association. Results: higher DI-GM scores were significantly associated with lower odds of RA. Each 1-point increase in DI-GM was linked to a 5 % reduction in RA odds [OR = 0.95 (0.92-0.99)]. Compared with individuals in the lowest DI-GM category (0-3), those with scores ≥ 6 had significantly reduced odds of RA [OR = 0.81 (0.66-0.99)]. Mediation analysis showed that SII partially mediated the DI-GM-RA association, accounting for approximately 21.3 % of the total effect. Conclusion: higher adherence to a gut microbiota-supportive dietary pattern was associated with lower odds of RA, partly through reduced systemic inflammation. These findings support the potential value of microbiome-informed dietary strategies in RA prevention.