New research finds vitamin D supplementation, in addition to standard asthma medication, could halve the risk of acute exacerbations which require hospitalization.  

Researchers from Queen Mary University of London analyzed the individual data from 955 participants in seven randomized controlled trials, which tested the use of vitamin D supplements.

Their analysis found a 30 percent reduction in the rate of asthma attacks requiring treatment with steroid tablets or injections from 0.43 events per person per year to 0.30.

The risk of experiencing at least one asthma attack requiring accident and emergency department attendance and/or hospitalizations were reduced by half, from 6 percent to 3 percent.

Vitamin D supplementation was found to be safe at the doses administered. According to the researchers, no instances of excessively high calcium levels or renal stones were seen, and serious adverse events were evenly distributed between participants taking vitamin D and those on placebo.

“These results add to the ever growing body of evidence that vitamin D can support immune function as well as bone health,” said lead researcher Professor Adrian Martineau in a statement. “On average, three people in the UK die from asthma attacks every day. Vitamin D is safe to take and relatively inexpensive so supplementation represents a potentially cost-effective strategy to reduce this problem.”

The data also allowed the researchers to discern which groups would respond best to vitamin D supplementation.

In particular, a strong and statistically-significant protective effect was seen in participants who had low baseline levels of vitamin D. These participants saw a 55 percent reduction in the rate of asthma exacerbations requiring treatment with steroid tablets or injections, from 0.42 events per person per year to 0.19.

However, due to relatively small numbers of patients within sub-groups, the researchers caution that they did not find definitive evidence to show that effects of vitamin D supplementation differ according to baseline vitamin D status.

The researchers also noted that the results are largely based on data from adults with mild to moderate asthma.

“Children and adults with severe asthma were relatively under-represented in the dataset, so our findings cannot necessarily be generalized to these patient groups at this stage,” said first author on the paper Dr. David Jolliffe, Queen Mary University of London in a statement.

“Further clinical trials are on-going internationally, and we hope to include data from them in a future analysis to determine whether the promise of today’s results is confirmed in an even larger and more diverse group of patients.”

Study findings were published in The Lancet Respiratory Medicine.