Association of a newly proposed dietary index for gut microbiota with phenotypic age acceleration: a cross-sectional study of NHANES 1999-2018.

BACKGROUND

Aging is closely linked to chronic diseases, and gut microbiota plays a significant role in this process. The Dietary Index for Gut Microbiota (DI-GM), a novel tool reflecting the potential impact of diet on gut microbiota diversity, has an unclear association with biological aging. This study aimed to evaluate the association between DI-GM and phenotypic age acceleration (PAA), revealing the potential regulatory effect of diet on aging.

METHODS

Data from 29,435 participants in NHANES 1999-2018 were analyzed using multivariable regression models to assess the association between DI-GM scores and PAA. Phenotypic age was estimated from 10 physiological indicators, with PAA defined as a positive age acceleration residual (ACR). DI-GM was constructed from 14 dietary components; higher scores indicate greater potential benefits to gut microbiota.

RESULTS

Higher DI-GM scores were significantly associated with a lower risk of PAA. After adjusting for covariates, each 1-point increase in DI-GM was linked to a 7% reduction in PAA risk (OR = 0.93, 95% CI = 0.91-0.95, P < 0.001) and a decrease of 0.33 in ACR (β = -0.33, 95% CI = -0.39 to -0.26, P < 0.001). Subgroup and sensitivity analyses confirmed these findings.

CONCLUSIONS

Higher DI-GM scores are significantly associated with reduced phenotypic age acceleration. Dietary improvements that promote gut microbiota health may effectively delay aging, providing scientific evidence for dietary interventions aimed at healthy aging.