The association between dietary inflammation index and the risk of rheumatoid arthritis in Americans

The correlation between dietary inflammation index (DII) and rheumatoid arthritis (RA) has been found, but the effect of confounding factors is not considered. This study aims to further explore the association between DII and RA risk by taking the Americans as the research object.

The data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES) database included 1819 self-reported RA individuals and 8602 non-RA individuals. The analytical methods include logistic regression, additive model, smooth curve fitting, and the recursive algorithm.

There was a positive correlation between DII and RA in Americans (β = 1.068, 95% CI = 1.026 to 1.111, P = 0.001). This result was still presented in the subgroup analysis, including age less than 50 years, female, other Hispanics, BMI ≥ 25, and federal poverty rate > 185%, and it was more pronounced in smokers. The results show that the superposition of DII and other risk factors would increase the risk of RA (β > 1.068). In addition, individuals with RA are inadequate in intake of anti-inflammatory foods, in line with the Mediterranean diet.

The inflammatory potential of the diet is positively correlated with the risk of RA, and has a superimposed effect with other risk factors, increasing the probability of the risk of disease. These results emphasize that reducing the intake of pro-inflammatory foods may be an effective measure to prevent the onset of rheumatoid arthritis. However, eating anti-inflammatory foods exclusively is not the best option. Intaking some pro-inflammatory foods like protein, energy, and total saturated acids may be necessary to maintain the physiological function of the human body. Key Points • Dietary inflammation index (DII) is positively correlated with RA risk. • When DII and other risk factors appear at the same time, the effects of the two will be superimposed on each other, increasing the risk of RA. • When the DII is the same, Hispanic has a higher incidence of RA. • Among the pro-inflammatory foods, the intake of protein, energy, and saturated fatty acids is still required by RA patients.