The Association of Essential Micronutrients in Serum with Immune-Mediated Inflammatory Diseases: A Cross-Sectional Study from NHANES

Background: Immune-mediated inflammatory diseases (IMIDs) occur when the immune system attacks the body’s own tissues, affecting approximately 8% of the global population. Objective: This study investigated the serum levels of a few redox-relevant essential micronutrients, aiming to explore their relationships with the prevalence of IMIDs and to identify the serum concentration ranges associated with the lowest observed prevalence of IMIDs. Methods: A cross-sectional study was conducted using NHANES 2013–2014 data, comprising 1493 participants. IMIDs were defined as the presence of asthma, celiac disease, psoriasis, or psoriatic/rheumatoid arthritis. Weighted binary logistic regression evaluated the association between serum selenium, vitamin D, and the zinc-to-copper ratio with the prevalence of IMIDs. We identified the serum-selenium quartile associated with the lowest observed prevalence of IMIDs in this dataset using quartile-based and threshold analyses, adjusting for smoking status, alcohol consumption, diabetes, and cancer history. Results: Higher serum selenium levels were significantly associated with a lower prevalence of IMIDs (OR: 0.627, 95% CI: 0.402–0.977). In contrast, no significant associations were observed for vitamin D or zinc-to-copper ratio. Quartile analysis revealed that individuals in the second quartile of serum selenium (1.51–1.65 μmol/L) had the lowest observed prevalence of IMIDs (18.85%), with significantly lower odds of IMIDs compared to the lowest (OR: 0.659, 95% CI: 0.447–0.971). However, sufficiency levels of vitamin D and the zinc-to-copper ratio were not significantly associated with a lower prevalence. Conclusion: The inverse association between higher serum selenium (1.51–1.65 μmol/L) and IMIDs was statistically significant in crude and partially-adjusted models but was attenuated and non-significant in the primary fully-adjusted weighted model. These findings suggest a potential observational link between selenium status and the prevalence of IMIDs that warrants further investigation.