Causal role of vitamin E in atopic dermatitis risk: A Mendelian randomization study

Prior studies suggested that vitamin E might be beneficial in alleviating atopic dermatitis, but confirming a causal link was hindered by limitations such as sample sizes and unaccounted confounders. The present study aimed to clarify this through Mendelian randomization (MR) analysis. GWAS summary statistics was obtained from public databases encompassing a study on vitamin E and two studies related to atopic dermatitis. Two sets of instrumental variables (IVs) were selected using lenient (p < 1e-5) and strict (p < 5e-6) thresholds for separate MR analyses. Inverse variance weighted (IVW) was used as the primary MR method, supplemented by six additional MR methods, and followed by a meta-analysis to consolidate the impact of vitamin E on atopic dermatitis from two independent studies. Furthermore, various sensitivity tests were performed to assess the reliability of the MR results. A meta-analysis of IVW analyses deriving from two different atopic dermatitis cohorts under lenient IV selection thresholds demonstrated that vitamin E exhibited a significant lowering risk of atopic dermatitis effect (OR = 0.817, 95% CI: 0.673-0.991, p = .041), which was validated under strict IV selection thresholds (OR = 0.822, 95% CI: 0.709-0.954, p = .010). In addition, six other MR methods remained parallel to IVW (OR > 1). Multiple sensitivity tests showed that MR analyses were not affected by heterogeneity and horizontal pleiotropy. Overall, this MR study supported vitamin E reducing the risk of atopic dermatitis. Consequently, maintaining an adequate intake of vitamin E could potentially serve as an effective preventive measure against atopic dermatitis.