Association between the dietary index for gut microbiota and gallstone disease: A cross-sectional analysis considering the Dietary Inflammatory Index

The dietary index for gut microbiota (DI-GM) reflects dietary patterns that may support or adversely affect gut microbial health. This study examined the association between DI-GM and prevalence of gallstone disease (GSD), while additionally exploring the potential mediating association of the Dietary Inflammatory Index (DII), using data from the National Health and Nutrition Examination Survey 2017–2020. This cross-sectional study analyzed 5669 adults from National Health and Nutrition Examination Survey 2017–2020. GSD status was defined by self-reported physician diagnosis. DI-GM scores were calculated from 14 dietary components categorized as beneficial or detrimental to gut microbiota. DII scores were derived from nutrient intake data. Associations were evaluated using multivariable logistic regression. Higher DI-GM scores were associated with a lower likelihood of GSD (adjusted odds ratio [OR] = 0.92, 95% confidence interval [CI]: 0.87–0.97, P  = .004). Individuals with DI-GM ≥ 6 had significantly reduced GSD risk (adjusted OR = 0.71, 95% CI: 0.55–0.91, P  = .007). The beneficial dietary component was inversely associated with GSD (adjusted OR = 0.93, 95% CI: 0.86–0.99, P  = .047). No significant interactions were observed across subgroups. Mediation analysis showed an inverse association between DI-GM and DII, with a small but significant indirect association (approximately 28%). Higher DI-GM scores are associated with a lower prevalence of GSD. These findings suggest a potential role of dietary inflammatory in this association; however, given the simultaneous measurement of exposure, mediator, and outcome, the results should be interpreted with caution.