Association between Vitamin B2 Intake and Prevalence of Rheumatoid Arthritis in the general United States population: A Cohort Study from the NHANES 1999-2018

Background The relationship between dietary intake of vitamin B2 and the prevalence of rheumatoid arthritis (RA) in the general United States population is an area of research which has not yet been extensively explored in the field of nutritional epidemiology, highlighting a significant research gap. Objective The present study aims to explore the potential association between dietary intake of vitamin B2 and the prevalence of rheumatoid arthritis in the general United States population. Methods This longitudinal cohort study analysed 8,761 individuals from the United States aged 20 years or older who participated in the National Health and Nutrition Examination Survey from 1999 to 2018. A comprehensive data set pertaining to the prevalence of rheumatoid arthritis (RA), the intake of dietary vitamin B2, and pertinent confounding variables was systematically collected and analysed. The potential association was investigated by means of a Cox regression analysis and spline curve fitting. Results Following the adjustment for confounding factors, a significant inverse relationship was identified between dietary intake of vitamin B2 and the prevalence of rheumatoid arthritis in the general United States population. The adjusted hazard ratios (HRs) for the second (Q2) and third (Q3) tertiles of vitamin B2 intake were 0.87 and 0.89, respectively. Non-linear modelling indicated a threshold effect, characterised by a curve that associated dietary intake of vitamin B2 with rheumatoid arthritis risk prevalence (p = 0.021). A critical analysis of the extant literature revealed an intake threshold of 1.7 mg/day, below which each unit increment in vitamin B2 intake was associated with a 34.2% decrease in the prevalence of rheumatoid arthritis risk (HR = 0.658). In contrast, no substantial correlation was identified between intake levels that exceeded this threshold and the prevalence of rheumatoid arthritis risk (HR = 0.977). Conclusion The findings of this study suggest a positive correlation between increased dietary intake of vitamin B2 and a reduced risk of rheumatoid arthritis in the general United States population. The dose-response relationship exhibits a non-linear pattern, featuring a critical inflection point at an intake of approximately 1.7 mg/day.