Micronutrients and Allergic Diseases: A Mendelian Randomization Study.

Introduction: Previous studies have indicated a controversy regarding the association between dietary micronutrient concentrations and the risk of allergic diseases. In this study, we employed Mendelian randomization (MR) analysis using data from two samples to investigate the causal relationship between circulating micronutrient concentrations and three allergic diseases.

Methods: In this study, we considered 16 circulating micronutrients as exposure variables (beta carotene, calcium, copper, folate, iron, lycopene, magnesium, phosphorus, selenium, vitamin A1, vitamin B6, vitamin B12, vitamin C, vitamin D, vitamin E, and zinc); and three common allergic diseases (allergic asthma [AA], atopic dermatitis [AD], and allergic rhinitis [AR]) as outcomes. The inverse variance weighted (IVW) method was primarily applied for MR analysis, supplemented by MR-Egger and weighted-median methods to corroborate the IVW results; and sensitivity analysis was conducted to ensure the robustness of the MR assumptions.

Results: Our results revealed that an increase in serum phosphorus and zinc concentrations may diminish the risk of AA, while for AD an increase in serum zinc concentration may reduce the risk, but an increase in serum vitamin C concentration may elevate the risk. As for AR, an increase in serum phosphorus and selenium concentrations appeared to be associated with a reduced risk. We did not find evidence for an association between other micronutrients and the risk of allergic diseases.

Conclusion: Our study indicates that an increase in serum phosphorus and zinc concentrations may reduce the risk of AA, while an increase in serum zinc concentration may reduce the risk of AD, but an increase in serum vitamin C concentration may elevate the risk of AD. An increase in serum phosphorus and selenium concentrations is associated with a reduced risk of AR. This provides additional support for research on the effects of micronutrients on allergic diseases.