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Vitamin D levels not linked to asthma or dermatitis

PLOS

Vitamin D supplementation is unlikely to reduce the risk of asthma in children or adults, atopic dermatitis, or allergies according to a new study published in PLOS Medicine by Brent Richards, of McGill University, Canada, and the Lady Davis Institute at the Jewish General Hospital, Canada, and colleagues.

Some previous epidemiological studies have suggested that low vitamin D levels are associated with increased rates of asthma, atopic dermatitis--an itchy inflammation of the skin--and elevated levels of IgE, an immune molecule linked to atopic disease (allergies). In the new work, researchers looked at genetic and health data on more than 100,000 individuals from previous large studies to determine whether genetic alterations that are associated with vitamin D levels predispose people to asthma, dermatitis, or high IgE levels.

The researchers found no statistically significant difference between rates of asthma (including childhood-onset asthma), atopic dermatitis, or IgE levels in people with or without any of the four genetic changes associated with lower levels of 25-hydroxyvitamin D. However, the results do not exclude an association between the outcomes and levels of 1,25-dihydroxyvitamin D, the active form of the vitamin, and more work will be needed to determine if the results hold true in non-European populations and in people with vitamin D deficiency.

"Our findings suggest that previous associations between low vitamin D and atopic disease could be due to spurious associations with other factors," said Dr. Despoina Manousaki, the lead author and a PhD student at the Lady Davis Institute. "Efforts to increase vitamin D levels will probably not result in decreased risk of adult and pediatric asthma, atopic dermatitis, or elevated IgE levels."

These findings contrast with a recent study from the same group which used similar methods to provide evidence supporting a causal role for vitamin D in the risk of multiple sclerosis, a common neurological disorder. "Our previous findings suggest that low vitamin D levels increase risk for some inflammatory diseases like multiple sclerosis, but these effects do not translate to other inflammatory diseases like asthma and atopic dermatitis", said Dr. Richards. Risk of multiple sclerosis is elevated in some population groups, including white people of European descent and women, and these findings suggest that people at risk for multiple sclerosis should ensure that they have adequate vitamin D levels, but that efforts to increase vitamin D would not be expected to protect against asthma.

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Research Article

Funding:

JBR received funding by the Canadian Institute of Health Research (FRN 119 462), the Canadian Foundation for Innovation (230146), and The Fonds de la Recherche en Santé Québec (27067). WOCMC, ML, EB, and FD received funding for genotyping of the GABRIEL data by grants from the European Commission (No. LSHB-CT-2006-018996-GABRIEL). WOCMC and ML received funding from the Wellcome Trust (WT084703MA). LP is funded by an MRC fellowship (MR/J012165/1) and works in the Medical Research Council Integrative Epidemiology Unit at the University of Bristol, which is supported by the Medical Research Council and the University of Bristol (MC_UU_12013/4). MF acknowledges the support of the Wellcome Trust core award (090532/Z/09/Z) and the BHF Centre of Research Excellence, Oxford (RE/13/1/30181). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests:

The authors have declared that no competing interests exist.

Citation:

Manousaki D, Paternoster L, Standl M, Moffatt MF, Farrall M, Bouzigon E, et al. (2017) Vitamin D levels and susceptibility to asthma, elevated immunoglobulin E levels, and atopic dermatitis: A Mendelian randomization study. PLoS Med 14(5): e1002294. https://doi.org/10.1371/journal.pmed.1002294

Author Affiliations:

Centre for Clinical Epidemiology, Department of Epidemiology, Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Montréal, Canada

MRC Integrative Epidemiology Unit, School of Social & Community Medicine, University of Bristol, Bristol, United Kingdom

Institute of Epidemiology I, Helmholtz Zentrum München-German Research Center for Environmental Health, Neuherberg, Germany

National Heart and Lung Institute, Imperial College London, London, United Kingdom

Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom

Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom

Genetic Variation and Human Diseases Unit, UMR-946, INSERM, Université Paris Diderot, Université Sorbonne Paris Cité, Paris, France

Population Health Research Institute, St George's University of London, London, United Kingdom

McGill University and Genome Québec Innovation Centre, Montréal, Canada

Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom

Departments of Medicine and Human Genetics, McGill University, Montréal, Canada

Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom

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