Dose-response association between vitamin D deficiency and atopic dermatitis in children, and effect modification by gender: a case-control study.

BACKGROUND: Vitamin D is a regulatory factor for immunity and skin barrier functions. It is hypothesized to be linked to atopic dermatitis (AD) which is characterized by interaction between epidermal barrier dysfunction and dysregulation of skin immune functions. METHODS: One hundred AD patients and one hundred and one normal controls were collected from outpatient clinic based on their clinical condition, both had measurement of 25-hydroxyvitamin D [25(OH)D]. We assessed the relationship between 25(OH)D deficiency and AD prevalence using adjusted Poisson regression model. RESULTS: Serum 25(OH)D levels were significantly lower in cases than controls (mean 35.1 versus 22.6 ng/mL, p < .001). The unadjusted prevalence ratios (PRs) (95% CI) for AD for comparing participants with intermediate and deficient vitamin D levels to those with optimal levels were 3.11 (1.91, 5.06) and 4.77 (2.99, 7.60), respectively. The association did not materially change after adjusting for potential confounders. In the fully adjusted analysis stratified by gender, PRs for AD for comparing male participants with intermediate and deficient vitamin D levels to those with optimal levels were 3.38 (1.21, 9.40) and 5.20 (1.91, 14.13), respectively, whereas in the female participants were 1.32 (0.96, 1.83) and 1.49 (1.04, 2.14), respectively (p-interaction <.001). CONCLUSION: In this case-control study in children, we found a statistically significant dose-response association between vitamin D deficiency and AD. We also observed a statistically significant effect modification of this association by gender. Further research is recommended to study this association longitudinally, and to examine whether treating vitamin D deficiency may potentially improve AD. Key points Question: Can atopic dermatitis be associated with vitamin D deficiency? Finding: Serum 25(OH)D levels were significantly lower in cases with AD than in controls. Prevalence ratios for comparing male participants with intermediate and deficient vitamin D levels to those with optimal levels were 3.38 (1.21, 9.40) and 5.20 (1.91, 14.13), respectively, whereas in the female participants were 1.32 (0.96, 1.83) and 1.49 (1.04, 2.14), respectively (p-interaction <.001). Meaning: vitamin D deficiency is associated with AD in children, effect modification of this association by gender was also observed.

The impact of active vitamin D administration on the clinical outcomes of acne vulgaris.

Acne vulgaris is one of the most common chronic inflammatory skin disorder affecting millions of people worldwide. Vitamin D deficiency has a role in various inflammatory skin diseases as acne. This study aimed to investigate the serum level of 25 hydroxy vitamin D in acne patients and to assess the efficacy and safety of active vitamin D in management of acne. This study was conducted on 100 patients with acne and 100 healthy controls, then the 100 acne patients were randomized to either the study group that received 0.25ug alfacalcidol daily or the placebo group that received oral placebo during the 3 months study period. Serum levels of 25-hydroxy-vitamin D were significantly lower in acne patients than in healthy control and were inversely correlated to the severity of acne. After alfacalcidol administration, the study group showed significant higher level of 25(OH) D levels (p < .05) compared to placebo group. In addition, median serum level of IL6 and TNFα significantly decreased (p < .05) in the study group in comparison to placebo group and as compared to their baseline results. Acne patients are more commonly to have vitamin D deficiency as compared to healthy people and hence, alfacalcidol might have a beneficial role in the acne management with no reported side effects.