Associations between dietary mineral intake and rheumatoid arthritis: evidence from UK Biobank and NHANES

OBJECTIVES: The relationship between dietary mineral intakes and the risk of rheumatoid arthritis (RA) remains limited. This study aims to investigate the associations between dietary mineral intakes with RA. METHODS: We evaluated the association between dietary mineral intakes and RA in 123 940 adults age 40-70 years. The observation period extended from April 2009 to December 2019, encompassing individuals who had no prior diagnoses of RA. This study selected common minerals from the UK Biobank and NHANES datasets for analysis, including calcium, iron, potassium, magnesium, zinc, phosphorus, copper, sodium and selenium. Cox proportional hazard models were performed to assess the association between dietary mineral intakes and RA in UK Biobank. Additionally, we validated the observed associations in NHANES to confirm the robustness. RESULTS: After a median follow-up period of 8.07 years, a total of 123 940 participants were included in this study. The high intakes of iron (HR = 0.804, 95% CI 0.687-0.940) and magnesium (HR = 0.823, 95% CI 0.704-0.962) were associated with a reduced risk of RA. Intakes of phosphorus (HRMiddle = 0.827, 95% CI 0.707-0.966, HRHigh = 0.794, 95% CI 0.679-0.928) and copper (HRMiddle = 0.819, 95% CI 0.702-0.955, HRHigh = 0.763, 95% CI 0.652-0.893) were inversely associated with risk of RA. Similar results were observed in NHANES, particularly iron, magnesium, phosphorus and copper. CONCLUSION: This study supported that dietary mineral intakes were inversely associated with RA, particularly dietary iron, magnesium, phosphorus and copper.