Gut microbiota plays a key regulatory role in the pathogenesis of gout, affecting not only uric acid metabolism but also deeply involved in inflammation response and immune regulation. The newly proposed gut microbiota dietary index (DI-GM) reflects the diversity of gut microbiota, but its relationship with gout has not been studied.

The analysis used data from the National Health and Nutrition Examination Survey (NHANES) (2007-2018) original data. Gout was identified using questionnaire survey, and the DI-GM was calculated using dietary recall data. Weighted multivariate logistic regression model was used to evaluate the relationship between DI-GM and gout in adult male, adjusting for sociodemographic factors, uric acid, body mass index (BMI), hypertension, diabetes, hyperlipidemia, estimated glomerular filtration rate (eGFR), etc. In addition, mediation analysis was conducted to evaluate the influence of blood inflammatory indicators (NLR, DNLR, MLR, NMLR, SIRI, SII) and oxidative balance score (OBS) on the relationship between DI-GM and gout in adult male. Restricted cubic spline (RCS) was used to examine potential nonlinear associations. In addition, propensity score matching (PSM) was used to minimize confounding and reduce the inherent biases of observational studies.

After data cleaning, a total of 11,858 adult male participants were included in the analysis, among which 801 were diagnosed with gout. Baseline characteristic analysis found that in adult male gout, in addition to well-known uric acid, BMI, eGFR, hypertension and diabetes with statistically significant differences (P<0.001), NLR, MLR, NMLR, SIRI and OBS were also significantly increased (P<0.05). After all covariates were adjusted, the weighted multivariate logistic regression model suggested that DI-GM score was significantly correlated with a lower risk of adult male gout (OR=0.94, 95% CI: 0.88-1.00, P=0.043). RCS analysis showed that DI-GM score was linearly negatively correlated with adult male gout (P for overall=0.033, P for nonlinear=0.811). Mediation analysis showed that OBS and SIRI had significant mediation effect, with total mediation proportion of 34.38% (P<0.05) and 5.62% (P<0.05). Mediation sensitivity analysis demonstrated that the results were stable. In addition, even after PSM, DI-GM score remained significantly correlated with the incidence of adult male gout.

The newly proposed DI-GM is significantly correlated with the prevalence of adult male gout. Mediation analysis showed that this relationship is largely mediated by OBS and SIRI, highlighting their key role. When treating male gout patients, clinicians are necessary to provide timely and effective dietary interventions for gout patients, combined with DI-GM, to avoid further aggravation of the disease.