Association Between the Dietary Index for Gut Microbiota and Metabolic Syndrome: Mediation Effects of Albumin and Systemic Immune-Inflammation Index.

With the development of society, the prevalence of metabolic syndrome (MetS) has been increasing year by year and has become a major global health threat. The dietary index for gut microbiota (DI-GM), a recently proposed dietary assessment metric, has attracted considerable attention. However, its association with MetS has lacked systematic research evidence. This study was based on data from 59,842 nationally representative participants in the 2007-2018 National Health and Nutrition Examination Survey (NHANES) database, using methods such as multivariable weighted logistic regression, restricted cubic splines (RCS), subgroup analysis, and mediation effect analysis to explore the association between DI-GM and MetS. The study showed a significant negative correlation between the DI-GM score and the risk of MetS (OR = 0.947 [0.921, 0.974]), and as the DI-GM score increases, this association becomes more pronounced. Subgroup analysis found no significant interactions, while mediation effect analysis further revealed that serum albumin and the systemic immune-inflammation index (SII) played a partial mediating role in this association. This study is the first to confirm a significant negative correlation between DI-GM and MetS risk, suggesting that optimizing dietary structure may be a feasible intervention for the prevention and treatment of metabolic syndrome.