Sex and obesity status modify the association between vitamin D and eczema among adolescents

Background Epidemiologic studies have reported inconsistent associations between vitamin D and eczema. This study sought to assess whether sex and obesity status could modify the association between vitamin D and eczema. Methods A cross-sectional study enrolled 763 adolescents in Kuwait. 25-hydroxyvitamin D (25(OH)D) was measured in venous blood. Current eczema was defined according to clinical history and characteristic morphology and distribution. Results In sex-stratified analysis, decreased 25(OH)D levels were associated with increased current eczema prevalence among males (adjusted odds ratio (aOR) tertile 1 vs. tertile 3 : 2.14, 95% confidence intervals (CI): 1.07–4.56), but not among females (aOR tertile 1 vs. tertile 3 : 1.08, 95% CI: 0.71–1.66). Further stratification by obesity status showed that lower 25(OH)D levels were associated with increased current eczema prevalence among overweight/obese males (per 10-unit decrease in 25(OH)D levels: aOR: 1.70, 95% CI: 1.17–2.46). Such an association was weaker and statistically non-significant among overweight/obese females (per 10-unit decrease in 25(OH)D levels: aOR: 1.26, 95% CI: 0.93–1.70). Conclusions Sex and obesity status modified the association between vitamin D levels and eczema, with an inverse association observed among overweight/obese males, but not among overweight/obese females. These results suggest that preventive and clinical management strategies could vary by sex and obesity status. Impact The current study showed that sex and obesity modify the association between vitamin D and eczema among adolescents. An inverse association between vitamin D and eczema was observed among overweight/obese males, but this association was not as pronounced among overweight/obese females. Vitamin D was not associated with eczema among underweight/normal weight males and females. The identification of effect modification by sex and obesity status add to the current scientific knowledge and further highlight the complexity of the association between vitamin D and eczema. These results may promote a more individualized approach to the future prevention and clinical management of eczema.