Association between dietary index for gut microbiota and the risk of cardiovascular disease: a prospective cohort study

The dietary index for gut microbiota (DI-GM) has been proposed based on studies to represent intestinal microbiome composition and is associated with cardiovascular disease (CVD) risk. A few cross-sectional studies from the National Health and Nutrition Examination Survey (NHANES) database have examined the association between DI-GM and the likelihood of CVD; however, there are no cohort studies from other communities. Therefore, this study examined the association between DI-GM and CVD risk using the Tehran Lipid and Glucose Study (TLGS) database. This cohort included 2,920 adults (≥ 19 years) without a history of CVD from TLGS (2006–2020). We calculated DI-GM using a food frequency questionnaire and ascertained incident CVD from participants’ medical records. We used the Cox proportional hazards model to assess the association between DI-GM and the risk of CVD. The mean age of participants was 39.3 years, and 55% of them were women. Over a median follow-up of 12.5 years, 233 cases of incident CVD were identified. There was an inverse association between every 1-unit increase in DI-GM and the risk of CVD, with a hazard ratio of 0.83 (95% CI: 0.77, 0.89). The restricted cubic spline displayed a dose-response relationship between DI-GM and incident CVD. According to the mediation analysis, the direct effect of DI-GM on CVD was independent of weight changes. The results of subgroup analyses indicated that the inverse association between DI-GM and CVD risk is independent of sex and weight. It seems there is an inverse association between DI-GM and the risk of CVD and its subtypes among the adult Iranian population. This association was not mediated by the percentage of weight change over the study period.