Association of a Novel Dietary Index Assessing Gut Microbiota Impact With Rheumatoid Arthritis: A Nationwide Population‐Based Study

ABSTRACT Growing research implicates the diet‐microbiota‐joint axis plays a key role in joint health. The Dietary Index for Gut Microbiota (DI‐GM) is a novel metric evaluating dietary effects on microbial communities, yet its potential link to rheumatoid arthritis (RA) is unestablished. This study aimed to assess the relationship between DI‐GM scores and RA. We conducted a cross‐sectional analysis of 29,656 participants using data from the National Health and Nutrition Examination Survey (NHANES) 2007–2020. DI‐GM scores were derived from 24‐h dietary recalls, and RA status was defined by self‐reported physician diagnosis. Weighted logistic regression was used to evaluate the association between DI‐GM and RA prevalence. Among included participants (weighted mean age 44.01 years; 49.48% female), 7.16% reported RA. After comprehensive adjustment, a significant inverse correlation was observed: each unit increase in DI‐GM score correlated with a 5.7% decrease in the odds of RA prevalence (odds ratio [OR] = 0.943; 95% confidence interval [CI]: 0.898–0.991). Individuals scoring DI‐GM ≥ 7 exhibited a 27.2% lower odds of having RA compared to those scoring ≤ 4 (OR = 0.728, 95% CI: 0.576–0.920). Restricted cubic spline analysis indicated a linear dose–response relationship ( p for nonlinear = 0.304). Furthermore, no significant subgroup interactions were detected (all p for interaction > 0.05). Our study found that higher DI‐GM scores linearly associate with diminished RA prevalence among US adults, highlighting a potential link between diet‐modulated gut microbiota and RA.