Ease Severe Asthma Attacks With Vitamin D

Adding oral vitamin D supplements to standard asthma medications can reduce the likelihood of severe asthma attacks, according to a new systematic review.

Low levels of vitamin D in the blood have been linked to increased risk of asthma attacks among both children and adults who have asthma. This had led to investigations into the potential role of vitamin D in asthma management to potentially reduce upper respiratory infections that can lead to asthma exacerbations. Several clinical trials have tested whether taking vitamin D supplements affect attacks, symptoms, and lung function in children and adults with asthma.

The new systematic review found 7 trials that involved 435 children and 2 studies that involved 658 adults. The majority of the ethnically diverse patients recruited to the studies had mild to moderate asthma; only a minority had severe asthma. Most patients continued to take their usual asthma medication while participating in the studies, which lasted for between 6 and 12 months.

Giving an oral vitamin D supplement reduced the risk of severe asthma attacks requiring hospital admission or emergency department attendance. The average number of attacks per person per year decreased from 0.44 to 0.28 with vitamin D, and vitamin D reduced the risk of attending hospitals with an acute asthma attack from 6 per 100 to around 3 per 100. Administration of vitamin D reduced the rate of exacerbations that required systemic corticosteroids and decreased the risk of having at least 1 exacerbation that required an ED visit or hospitalization or both.

Vitamin D did not improve lung function or day-to-day asthma symptoms, and it did not increase the risk of adverse effects at the doses that were tested. The oral vitamin D₃ (cholecalciferol) supplementation ranged from 4 to 12 months, and dosing varied widely from 500 to 1200 IU/d to weekly, monthly, or twice-monthly dosing, including, at times, boluses.

“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,” said the review's lead author, Professor Adrian Martineau from the Asthma UK Centre for Applied Research, Queen Mary University of London.

“This is an exciting result, but some caution is warranted,” Dr Martineau said. “First, the findings relating to severe asthma attacks come from just three trials: most of the patients enrolled in these studies were adults with mild or moderate asthma. Further vitamin D trials in children and in adults with severe asthma are needed to find out whether these patient groups will also benefit.

“Second, it is not yet clear whether vitamin D supplements can reduce risk of severe asthma attacks in all patients, or whether this effect is just seen in those who have low vitamin D levels to start with.”

Further analyses to investigate these questions are ongoing, he said, with results expected in the next few months.

The researchers published their results on September 5, 2016 in the Cochrane Database of Systematic Reviews.