Could Vitamin D Supplementation Reduce Risk of Atopic Diseases?
Vitamin D levels were not associated with atopic dermatitis or asthma, according to the results of a recent study. The results are contrary to prior research that suggested a potential link between low levels of vitamin D and elevated immunoglobulin E (IgE) associated with inflammation in both allergies and allergic asthma.
The researchers used Mendelian randomization methodology to analyze data from the UK Biobank resource and from SUNLIGHT, GABRIEL, and EAGLE eczema consortia. Four single-nucleotide polymorphisms strongly associated with 25-hydoxyvitamin D (25OHD) levels from 33,996 individuals were used to estimate the effect of lowered 25OHD levels on the risk of asthma in a cohort of 146,761 individuals, childhood-onset asthma in a cohort of 15,008 individuals, atopic dermatitis in a cohort of 40,835 individuals, and elevated IgE levels in a cohort of 12,853 individuals.
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Overall, researchers did not find any associations between the four 25OHD-lowering alleles and asthma, atopic dermatitis, or elevated IgE levels.
The analysis with Mendelian randomized showed that odds ratio per standard deviation decrease in log-transformed 25OHD was 1.03 for asthma, 0.95 for childhood-onset asthma, and 1.12 for atopic dermatitis, and the effect size on log-transformed IgE levels was -0.40. In sensitivity analyses that assessed for population stratification, pleiotropy, vitamin D synthesis, and metabolism pathways, these results remained consistent.
However, the study did not examine the association between 1,25-dihydroxyvitamin D, the active form of vitamin D, and the risk of atopic disease, or include individuals of non-European ancestry.
“In this study, we found no evidence that genetically determined reduction in 25OHD levels conferred an increased risk of asthma, atopic dermatitis, or elevated total serum IgE, suggesting that efforts to increase vitamin D are unlikely to reduce risks of atopic disease,” the researchers concluded.
—Melissa Weiss
Reference:
Manousaki D, Paternoster L, Standl M, et al. Vitamin D levels and susceptibility to asthma, elevated immunoglobulin E levels, and atopic dermatitis: A Mendelian randomization study [published online May 9, 2017]. PLoS Med. https://doi.org/10.1371/journal.pmed.1002294.