Association of the Dietary Index for Gut Microbiota and Cardiovascular‐Kidney‐Metabolic Syndrome: The Mediation Effect of Phenotypic and Biological Age Acceleration, <scp>BMI</scp> , and <scp>BRI</scp>

The relationship between gut microbiota, diet, and cardiovascular-kidney-metabolic (CKM) health has attracted attention. However, the relationship between the dietary index for gut microbiota (DI-GM) and CKM syndrome has not yet been studied. Patients diagnosed with CKM syndrome from the NHANES 2007-2018 data were included. Dietary recall data were used to calculate DI-GM. Restricted cubic splines (RCS) were employed to explore nonlinear relationships and determine the threshold for DI-GM. The relationship between DI-GM and CKM syndrome was analyzed using weighted logistic regression. Further, potential mediating roles of phenotype age acceleration (PAA), biological age acceleration (BAA), body mass index (BMI), and body roundness index (BRI) were explored. Sensitivity analysis using inverse probability of treatment weighting (IPTW) was also conducted. A total of 7252 participants were included, with the high DI-GM group as the reference. In the crude model, the risk of CKM syndrome in the low DI-GM group was significantly higher (OR = 1.27, 95% CI = 1.09, 1.49, <i>p</i> < 0.05). This association remained significant in the fully adjusted model (OR = 1.34, 95% CI = 1.10, 1.64, <i>p</i> < 0.05). The results of the IPTW analysis were consistent with the above findings. In the association between DI-GM and CKM syndrome, significant mediating effects were observed for PAA (mediated proportion (MP): 14.84%, <i>p</i> < 0.001), BAA (MP: 21.45%, <i>p</i> < 0.001), BMI (MP: 24.17%, <i>p</i> < 0.001), and BRI (MP: 35.85%, <i>p</i> < 0.001). Low DI-GM is associated with an increased prevalence of CKM syndrome. PAA, BAA, BRI, and BMI significantly mediate the relationship between DI-GM and CKM syndrome.