Associations between gut microbiota-modulating diets and their components and metabolic syndrome

Diet and gut microbiota alterations are key contributors to metabolic syndrome (MetS). As the Dietary Index for Gut Microbiota (DI-GM) captures diet–microbiome interplay, we examined the associations of DI-GM and its components with MetS. A total of 13,684 participants aged 20 years or older from the National Health and Nutrition Examination Survey 2007–2018 were included. DI-GM scores were calculated based on the mean dietary intake from two 24-h dietary recalls. Survey-weighted logistic regression, restricted cubic splines, and stratified analyses were used to assess associations, nonlinear dose–response patterns, and susceptible subgroups. Furthermore, weighted quantile sum (WQS) regression was employed to evaluate the collective impact of DI-GM components on MetS risk. Higher DI-GM scores were associated with a lower odds of MetS, particularly for the unfavorable gut microbiota component (DI-GM: OR = 0.90, 95% CI: 0.86–0.93; unfavorable component: OR = 0.80, 95% CI: 0.76–0.85). Participants with scores ≥ 6 had markedly lower odds of MetS (OR = 0.63, 95% CI: 0.54–0.74) compared with those scoring 0–3 (P for trend < 0.001). Restricted cubic spline analyses indicated a linear association between DI-GM and MetS. The inverse association was more pronounced among individuals without diabetes (P for interaction < 0.05). Higher DI-GM scores were associated with lower odds of MetS. These findings highlight the potential value of microbiota-focused dietary assessment for informing MetS-related dietary research and prevention strategies.