Work

The association between a newly proposed gut microbiota dietary index and obesity among U.S. adults: a cross-sectional analysis based on NHANES 1999–2020

Year: 2025

Type: article

Abstract: OBJECTIVE: Obesity is linked to gut microbiota dysbiosis, and diet is a key determinant influencing the gut microbiome. This study examined the association between a newly proposed Dietary Index for Gut Microbiota (DI-GM) and obesity in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020. METHODS: A total of 41,159 adults aged ≥ 20 years were included, with 15,327 individuals classified as obese (BMI ≥ 30 kg/m²) and 25,832 as living without obesity. DI-GM comprises 13 components deemed either beneficial or unfavorable to the gut microbiome, yielding a total score ranging from 0 to 13. Weighted logistic regression assessed the relationship between DI-GM (continuous and categorical) and obesity, adjusting for demographic and lifestyle factors plus comorbidities. Restricted cubic spline, stratified analyses, multiple imputation, and propensity score matching were also performed. RESULTS: Participants with obesity had a significantly lower mean DI-GM score than those without obesity (4.32 vs. 4.65, P < 0.001). Each 1-point increase in DI-GM was associated with 13% lower obesity odds (OR = 0.87, 95% CI: 0.85-0.88) in the crude model, remaining robust (OR = 0.88, 95% CI: 0.87-0.90, P < 0.001) after full adjustment. Higher DI-GM scores were linearly linked to lower odds of obesity, supported by multiple imputation and propensity score matching (P < 0.001). CONCLUSION: In this nationally representative U.S. population, a more microbiota-oriented diet, as proxied by higher DI-GM scores, was independently associated with lower odds of obesity. Prospective and randomized trials are warranted to verify causality and investigate underlying mechanisms.

Source: Nutrition Journal

DOI: 10.1186/s12937-025-01249-8