Dietary Index for Gut Microbiota and Prevalent Hypertension in Chinese Adults: A Cross-Sectional Study of Metabolic, Inflammatory, and Microbiota-Related Pathways

Abstract Background The Dietary Index for Gut Microbiota (DI-GM) is a literature-based dietary index designed to characterize dietary patterns potentially supportive of a favorable gut microbiota. Evidence regarding the association between DI‑GM and hypertension in Chinese populations is scarce. We investigated the association between DI-GM and hypertension and explored potential metabolic, inflammatory, and gut microbiota-related pathways. Methods This community-based cross-sectional study included 1,700 Chinese adults aged ≥ 20 years. Dietary intake was assessed using a validated 112-item semi-quantitative food frequency questionnaire, and DI-GM scores were calculated based on 14 food components. Hypertension was defined by blood pressure measurements, physician diagnosis, or antihypertensive medication use. Multivariable logistic regression models were used to evaluate associations between DI-GM and hypertension with sequential adjustment for demographic, lifestyle, dietary, anthropometric, cardiometabolic, inflammatory, renal, and gut microbiota-related factors. Mediation analyses explored potential indirect associations through HOMA-IR, hs-CRP, NLR, TMAO, and LPS, recognizing the cross-sectional nature of these analyses. Results Higher DI-GM scores were associated with lower BMI, waist circumference, blood pressure, HOMA-IR, triglycerides, hs-CRP, TMAO, and LPS, and with higher HDL-C and eGFR. In crude analysis, each one-unit increase in DI-GM was associated with lower odds of prevalent hypertension (OR = 0.933, 95% CI: 0.889–0.979), and participants in Q4 had lower odds than those in Q1 (OR = 0.714, 95% CI: 0.539–0.945). After adjustment for dietary and anthropometric factors, the association was markedly attenuated and became non-significant (fully adjusted Q4 vs. Q1 OR = 1.142, 95% CI: 0.802–1.626). Exploratory mediation analyses suggested potential indirect associations through HOMA-IR (25.8%), hs-CRP (21.1%), and TMAO (12.8%), although these should not be interpreted as causal due to the cross-sectional design. Conclusions Higher DI-GM was associated with a favorable cardiometabolic profile and lower levels of several gut microbiota-related biomarkers, but its association with hypertension was not independent of broader dietary and cardiometabolic characteristics. Exploratory mediation analyses identified statistical indirect associations involving HOMA-IR, hs-CRP, and TMAO; these findings should not be interpreted as evidence of causal mediation given the cross-sectional study design.