Sun Exposure, Dietary Vitamin D and Vitamin D Status in Adult Atopic Dermatitis: A Case Control Study

ABSTRACT

@#Atopic dermatitis (AD) and its severity has been inconsistently associated with lower vitamin D levels as multiple other factors that influence vitamin D status were not always assessed. Methods: A case control study involving AD patients and controls ≥18 years old was performed. Exclusion criteria were systemic immunosuppression ≤ 4 weeks prior to recruitment, renal or hepatic impairment, parathyroid diseases and vitamin D or calcium supplementation. Healthy controls were matched for age, gender, ethnicity, Fitzpatrick skin type and body mass index (BMI). Sun exposure, a 3-day, 24-hour dietary recall and serum 25-hydroxyvitamin D were measured. Results: 38 AD patients and 38 controls participated. Majority had Fitzpatrick skin type IV. Vitamin D was lower in AD [15.9(9.9-24.0)ng/ml] than controls [17.3(14.4-27.2)ng/ml], p= 0.028. It was sufficient in 16(42.1%) AD and 15(39.5%) controls, insufficient in 7(18.4%) AD and 22(57.9%) controls and deficient in 15(39.5%) AD compared to 1(2.6%) control. Sun exposure was similar in both groups. AD had significantly higher dietary vitamin D intake [1.5(0.6-3.1) vs 0.6 (0.3-1.0)µg]. AD was an independant risk for vitamin D deficiency with OR 17.52; 95%CI1.4- 212.7 and vitamin D insufficiency OR 0.26;95%CI0.07-0.95. Vitamin D levels did not correlate with AD severity. Conclusion: AD is a risk for vitamin D deficiency despite higher dietary intake and similar skin type, BMI and sun exposure as controls.