Milk products are a major part of the western diet, but the role of their effect in rheumatoid arthritis (RA) is controversial. The objective of this study was to explore the relationship between milk products and RA in the United States (US) population.

In the cross-sectional study, a total of 12,813 participants aged 20years or older were selected from the National Health and Nutrition Examination Survey (NHANES). Consumption of milk products was collected by personal interview, and RA status was obtained by self-reported questionnaires. The association between milk products and RA was estimated by using the weighted logistic regression model.

We found a negative association of once a day or more milk products intake with self-reported RA prevalence (odds ratio [OR]: 0.68; 95% confidence interval [CI]: 0.53 to 0.86; P<0.001). A linear trend between consumption of milk products and the prevalence of RA (P<0.01) was also observed. In subgroup analysis, protective effects of milk products on RA were more pronounced in several groups (i.e., Mexican Americans, highly educated and drinking individuals, etc.). However, no interaction effect of stratification variables and the frequency of milk products intake with RA was detected. After imputing missing data, the sensitivity analysis showed the same association.

This study suggested a negative association between consumption of milk products and RA among US population. Further investigations are warranted to validate the causal association and the underlying mechanism.