Dietary index for gut microbiota score is inversely associated with carotid calcified plaque score in ischemic stroke patients

Background Diet influences gut microbiota-derived metabolites, which may affect vascular inflammation and calcification. The Dietary Index for Gut Microbiota (DI-GM) captures dietary patterns hypothesized to support favorable microbial metabolite profiles. In this study, we examined whether higher DI-GM scores are associated with lower carotid calcification burden in ischemic stroke patients and whether trimethylamine N-oxide (TMAO) is statistically associated with this relationship, without implying causality. Method In this cross-sectional study of 788 ischemic stroke patients from Central Hospital Affiliated to Shandong First Medical University, we calculated DI-GM scores from validated food frequency questionnaires and quantified carotid calcification using the Agatston method via computed tomography angiography. Plasma TMAO levels were measured by enzyme-linked immunosorbent assay (ELISA) ELISA. Results Our findings revealed that participants in the highest DI-GM tertile had significantly lower calcification scores (76.07 ± 14.55) compared to the lowest tertile (316.00 ± 75.33, p < 0.001). Higher DI-GM scores correlated with lower TMAO, and decreased inflammatory markers (all p < 0.001). Each one-unit increase in DI-GM was independently associated with lower calcification odds (adjusted OR = 0.60, p = 0.02). Mediation analysis confirmed that TMAO significantly mediated these associations, accounting for substantial proportions of the total effects of DI-GM score on inflammatory markers, plaque thickness, and calcification score. Conclusion Higher DI-GM score is cross-sectionally associated with lower carotid calcification and TMAO-mediated pathways, but causality remains unproven without longitudinal and microbiome-sequencing data.