Given the contentious relationship between gut microbiota and kidney stones, we investigated the association between the Dietary Index for Gut Microbiota (DI-GM) and the prevalence of kidney stones in a nationally representative sample from the United States.

We analyzed data from 20,469 participants in the National Health and Nutrition Examination Survey (NHANES). A multivariate logistic regression model was used to identify the correlation between DI-GM scores and kidney stone incidence, supplemented by smooth curve fitting for further exploration. To validate our findings, we performed subgroup analyses, interaction tests, and sensitivity analyses.

In this study, the average age of participants with kidney stones (59.75 ± 11.52 years) was higher than that of participants without stones (57.81 ± 11.66 years). In the fully adjusted multivariable logistic regression model, each unit increase in DI-GM scores was associated with a 5% reduction in kidney stone incidence (OR = 0.95; 95% CI: 0.92–0.98; P < 0.001). When comparing DI-GM groups, the fourth group demonstrated a 21% reduction in kidney stone incidence relative to the first group (OR = 0.79; 95% CI: 0.70–0.89; P < 0.001). A smoothed curve fit revealed a negative linear relationship, and both subgroup and the robustness of these findings was confirmed by sensitivity analyses.

Our findings indicate a linear association between DI-GM scores and the incidence of kidney stones, with higher DI-GM scores linked to a lower incidence of kidney stones.