Serum 25-Hydroxyvitamin D Concentrations and Atopic Dermatitis in Early Childhood: Findings from the Japan Environment and Children’s Study

Abstract

Vitamin D (VitD) may affect immune system modulation and result in the development of atopic dermatitis (AD). However, published findings have remained controversial. We investigated the association between early-life 25-hydroxyvitamin D (25(OH)D) levels and AD risk at childhood with a birth cohort. The data were obtained from “the Japan Environment and Children’s Study (JECS)” and “the Sub-Cohort study of JECS” performed with children aged 2 years. “Liquid chromatography-tandem mass spectrometry” was used to measure VitD. The information on AD was obtained from parents’ answers to a questionnaire when their children were aged 3 years. In order to explain the seasonal effects on VitD levels, a deseasonalized continuous variable was further calculated. The logistic regression models were fitted to evaluate the effect of VitD on childhood AD. The study included 4378 children with complete data on VitD and AD. The results from models indicated that low VitD at 2 years was not a risk factor for the development of AD at 3 years, after adjusting for potential confounders. Moreover, there was no U-shape relationship between deseasonalized VitD and childhood AD. Overall, early-life 25(OH)D levels were not link to the increased risk of developing childhood AD.

Smoking Exposure Is Associated with Serum Vitamin D Deficiency in Children: Evidence from the Japan Environment and Children’s Study

“…Although serum 25(OH)D concentration is the best marker to reflect VD concentrations in the body, no single cutoff value has been agreed upon by health agencies for serum 25(OH)D concentration to define VDD. Second, serum VD status was evaluated according to a single blood test, which may not reflect long-term VD in the body very well [ 20 , 21 ]. Third, a value of 25(OH)D was truncated as 4 in this study if a value of serum 25(OH)D2 or 25(OH)D3 was lower than 4 ng/mL, which may cause an overestimation of VD level [ 18 , 20 ].…”

“…Second, serum VD status was evaluated according to a single blood test, which may not reflect long-term VD in the body very well [ 20 , 21 ]. Third, a value of 25(OH)D was truncated as 4 in this study if a value of serum 25(OH)D2 or 25(OH)D3 was lower than 4 ng/mL, which may cause an overestimation of VD level [ 18 , 20 ]. Fourth, the information on tobacco smoke exposure was collected from the questionnaires, which may underreport smoking and could not reflect the precise degree of exposure to tobacco overall.…”

“…In addition, we fitted the linear regression model for de-seasonalized serum 25(OH)D concentrations [ 19 ]. Calculation details for de-seasonalized serum 25(OH)D concentrations were published in our previous study [ 20 ]…”

Causal Associations between Vitamin D Levels and Psoriasis, Atopic Dermatitis, and Vitiligo: A Bidirectional Two-Sample Mendelian Randomization Analysis

“…However, Lucas et al suggested no statistically significant difference of blood 25(OH)D 3 levels between atopic dermatitis patients and controls [13]. A cohort study of 4378 children indicated that low 25(OH)D levels at the age of two years old was not a risk factor for the development of atopic dermatitis at age of three years of age [14]. Most of the published studies have focused on the associations between the serum concentrations of 25(OH)D or 25(OH)D 3 and diseases, but the role of C3-epi-25(OH)D 3 in psoriasis, atopic dermatitis, and vitiligo has not been studied yet.…”

“…These findings suggest that vitamin D might play a role in calcium homeostasis, immune regulation, anti-bacterial, and anti-inflammation. Early epidemiological studies have reported associations of blood 25(OH)D or 25(OH)D 3 levels with psoriasis, atopic dermatitis, and vitiligo [10][11][12], but concluded conflicting association results [13][14][15][16]. For example, Ng et al found a significantly lower blood 25(OH)D level in atopic dermatitis patients than healthy controls and low serum vitamin D levels were associated with disease severity [10].…”