Supplementary Material for: Comorbidity of Vitamin A and Vitamin D Deficiency Exacerbates the Severity of Atopic Dermatitis in Children

<b><i>Background:</i></b> Several studies have suggested that vitamin D (VD) deficiency (VDD) is associated with atopic dermatitis (AD). However, little is known about the relationship between AD and vitamin A (VA). The interaction between VA and VD on AD requires further study. <b><i>Objective:</i></b> We detected serum levels of VA and VD in children with AD to explore how VA deficiency (VAD) and VDD affect AD severity. <b><i>Methods:</i></b> We assessed the SCORing Atopic Dermatitis (SCORAD) index, total immunoglobin E levels and peripheral blood eosinophil counts. VA and VD levels were determined with high-performance liquid chromatography. Correlations among variables were investigated with Pearson’s correlation analysis. <b><i>Results:</i></b> The VD and VA levels were significantly lower in children with AD than in normal children (p &lt; 0.001, p = 0.0423). Both VD and VA levels were negatively correlated with SCORAD scores. The SCORAD scores were significantly higher in AD patients with both VDD and VAD (co-deficiency) than in other AD patients. Significant inverse correlations were observed between peripheral blood eosinophil counts and serum VA and VD levels. <b><i>Conclusions:</i></b> VA and VD co-deficiency may exacerbate AD symptoms in children, but the specific mechanism underlying this relationship requires further study. These findings may indicate the need for studies evaluating the use of VD and VA as potential treatments for AD patients.