Specific dietary micronutrients are causally associated with arthritis subtypes: results from the NHANES 2015-2018 and Mendelian randomization study.

micronutrients (MNs) in the diet are linked to arthritis, but the causal relationships and dose-dependent effects remain unclear. using the National Health and Nutrition Examination Survey (NHANES) and genome-wide association studies (GWAS) databases, multivariate logistic regression, restricted cubic splines (RCS), and Mendelian randomization (MR) were applied to analyze MNs' impact on arthritis. multivariate logistic regression identified six MNs significantly associated with arthritis: calcium (OR = 0.74 [95 % CI, 0.60, 0.92] p = 0.013), magnesium (OR = 0.74 [95 % CI, 0.62, 0.89] p = 0.003), selenium (OR = 0.62 [95 % CI, 0.50, 0.76] p = 0.0001), folic acid (OR = 0.76 [95 % CI, 0.61, 0.94] p = 0.018), vitamin E (OR = 0.77 [95 % CI, 0.64, 0.92] p = 0.01), vitamin B6 (OR = 0.64 [95 % CI, 0.53, 0.78] p = 0.0001). RCS analysis revealed significant non-linear relationships for vitamin B6, vitamin E, folic acid, and selenium (p < 0.05). MR analysis only confirmed causal associations in specific MNs and subtypes of arthritis: calcium and rheumatoid arthritis (OR = 0.648 [95 % CI, 0.436, 0.962] p = 0.031), vitamin B12 and monoarthritis (OR = 2.876 [95 % CI, 1.240, 6.667] p = 0.014), potassium and pyogenic arthritis (OR = 2.124 [95 % CI, 1.003, 4.497] p = 0.049), vitamin B6 and pyogenic arthritis (OR = 1.744 [95 % CI, 1.034, 2.940] p = 0.037), vitamin B12 and other arthritis (OR = 1.414 [95 % CI, 1.035, 1.932] p = 0.03). this study reveals the causal relationship between specific MNs and certain arthritis subtypes, while also observing dose-dependent associations between other MNs and arthritis. These findings provide valuable insights for dietary interventions and preventive strategies targeting arthritis.