Association between dietary index for gut microbiota and kidney stones with body mass index as a potential mediator: A cross-sectional study

Dietary habits are associated with kidney stones, yet the association between the newly proposed dietary index for gut microbiota (DI-GM), which assesses the impact of diet on gut microbiota health, and kidney stones remains unclear. This study aims to evaluate the association between DI-GM and kidney stones. This cross-sectional study utilized data from the 2007 to 2020 cycles of the National Health and Nutrition Examination Survey, involving adults aged 20 years and older. DI-GM was calculated using dietary recall data, while the kidney stone status was determined based on self-reported questionnaire responses. The associations between DI-GM and kidney stones were explored using multivariable logistic regression, with mediation analysis conducted to assess the potential mediating effect of body mass index (BMI). A total of 26,712 participants were included, with a kidney stones prevalence of 9.91%. In the fully adjusted logistic regression model, higher DI-GM scores and beneficial gut microbiota scores were associated with a lower prevalence of kidney stones (DI-GM, odds ratio: 0.94, 95% confidence interval [CI]: 0.90-0.98; beneficial gut microbiota, odds ratio: 0.91, 95% CI: 0.85-0.98). Furthermore, BMI mediated the association between DI-GM and kidney stones (mediation proportion: 12.32%, 95% CI: 7.39%-22.4%, P < .001). DI-GM was negatively associated with kidney stones prevalence, with BMI mediating this association. These findings suggest a potential role of diet in kidney stone risk reduction.