Taking vitamin D supplements along with standard systemic corticosteroids halves the rate of severe asthma attacks that lead to either hospitalization or a visit to the emergency department, and reduces the rate of asthma attacks requiring steroid treatment by nearly one third, according to findings from a recent meta-analysis in the journal Lancet Respiratory Medicine.
The study also found that vitamin D supplementation greatly reduced severe asthma attacks in patients with insufficient vitamin D levels.
“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 Adrian Martineau, PhD, Clinical Professor of Respiratory Infection and Immunity at Queen Mary University of London, in London, UK.
“On average, three people in the UK die from asthma attacks every day,” Dr. Martineau added. “Vitamin D is safe to take and relatively inexpensive, so supplementation represents a potentially cost-effective strategy to reduce this problem.”
For this meta-analysis, researchers analyzed individual data on 955 asthma patients from seven randomized controlled trials investigating the effects of vitamin D supplementation on the risk of asthma exacerbations.
Results showed that vitamin D did reduce the overall rate of asthma exacerbations treated with systemic corticosteroids by 30% (from 0.43 events per person per year to 0.30 events per person per year).
Because individuals with the lowest baseline levels of a micronutrient may derive the greatest benefit from its replacement, the researchers also performed a subgroup analysis to investigate whether vitamin D could reduce asthma exacerbations in people with insufficient vitamin D levels (baseline status of less than 25 nmol/L). They found that vitamin D, along with systemic corticosteroids, did reduce exacerbations in these patients by 55% (from 0.42 events to 0.19 events per person per year).
However, vitamin D supplementation did not significantly reduce the rate of severe asthma attacks in patients with higher baseline status. Due to relatively small numbers of patients within subgroups of patients, the researchers could show no definitive evidence that the effects of vitamin D differed across subgroups.
Subgroup analysis didn't provide consensus on dosing vitamin D supplements either, although the doses given to patients were found to be safe with no instances of elevated blood calcium levels or kidney stones. Serious adverse events were comparable between vitamin D and placebo groups.
“Our 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,” noted first author David Jolliffe, PhD, postdoctoral researcher at Queen Mary University of London.
“Further clinical trials are ongoing 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,” Dr. Jolliffe added.