Research News

Taking vitamin D in addition to drugs reduces severe asthma attacks, finds review

BMJ 2016; 354 doi: (Published 06 September 2016) Cite this as: BMJ 2016;354:i4809
  1. Susan Mayor
  1. London

Taking an oral vitamin D supplement in addition to standard asthma drugs reduces the risk of severe asthma attacks that require systemic corticosteroids and lowers exacerbations needing hospital admission or emergency department care, a Cochrane review of clinical trials in adults and children with asthma has found.1

Low blood levels of vitamin D have been associated with increased risk of asthma attacks in children and adults with asthma. Several clinical trials have investigated whether vitamin D might improve control of asthma but have differed widely in design and duration.

Cochrane reviewers undertook a meta-analysis of placebo controlled trials that lasted for at least 12 weeks to evaluate the impact of vitamin D supplements on severe asthma exacerbations. After reviewing the literature they found that seven trials, which included 435 children, and two studies, involving 658 adults, met the review criteria. Most study participants had mild to moderate asthma, and the studies lasted four to 12 months.

The review’s results, published in the Cochrane Database of Systematic Reviews and reported at the European Respiratory Society International Congress, showed that taking vitamin D reduced the risk of having at least one asthma exacerbation requiring a visit to a hospital emergency department or hospital admission or both (odds ratio 0.39 (95% confidence interval 0.19 to 0.78)). The number needed to treat with vitamin D to avoid a severe asthma attack was 27 patients.

Administration of vitamin D also reduced the rate of asthma exacerbations requiring systemic steroids (rate ratio 0.63 (0.45 to 0.88)). But there was little or no effect on measures of lung function or day to day asthma symptoms.

The lead author of the review, Adrian Martineau, from the Asthma UK Centre for Applied Research, Queen Mary University of London, said, “We found that taking a vitamin D supplement in addition to standard asthma treatment significantly reduced the risk of severe asthma attacks without causing side effects.”

However, he cautioned that the findings regarding severe asthma attacks came from only three trials, which had included mainly patients with mild or moderate asthma. He noted, “Further vitamin D trials in children and adults with severe asthma are needed to find out whether these patient groups will also benefit.”

Martineau said that it was not yet clear whether vitamin D supplements can reduce the risk of severe asthma attacks in all patients or only in those with low vitamin D levels. He said, “Further analyses to investigate these questions are ongoing, and results should be available in the next few months.”


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