Adherence to the Dietary Index for Gut Microbiota and reduced risk of nephrolithiasis: a case-control study of Chinese adults.

OBJECTIVE: Nephrolithiasis represents a substantial clinical burden worldwide. The Dietary Index for Gut Microbiota (DI-GM) assesses dietary impacts on gut microbiota. However, its association with the risk of nephrolithiasis remains unclear in Chinese adults. METHODS: We conducted a case-control study using the Shenyang sub-cohort of the Tianjin Chronic Low-Grade Systemic Inflammation and Health (TCLSIH) cohort. Cases were 278 patients with nephrolithiasis. Controls were 556 healthy individuals, matched 1:2 by age and sex. Dietary intake was assessed using a validated food frequency questionnaire (FFQ) to calculate DI-GM scores. Multivariable conditional logistic regression evaluated the association. Restricted cubic spline (RCS) explored non-linear associations, and subgroup analyses were stratified by age and sex. RESULTS: Higher DI-GM scores were significantly associated with lower risk of nephrolithiasis. After adjustment, the risk decreased progressively with increasing DI-GM scores (P for trend < 0.05). Individuals with DI-GM ≥ 8 had 83% lower risk than those scoring 0-5 (odds ratio [OR] = 0.17, 95% confidence interval [CI]: 0.08-0.36). The association was consistent across age and sex subgroups, with no non-linearity (P for non-linearity > 0.05). CONCLUSION: In Chinese adults, higher adherence to the DI-GM was associated with lower risk of nephrolithiasis. This finding suggests gut-friendly dietary patterns may be associated with a lower likelihood of nephrolithiasis. Future prospective studies are warranted to confirm this association.