Taking an oral vitamin D supplement in addition to standard asthma medication is likely to reduce severe asthma attacks, according to research led by Queen Mary University of London (QMUL).
Asthma is a common chronic disease affecting about 300 million people worldwide, with symptoms including wheezing, coughing, chest tightness and shortness of breath.
Low blood levels of vitamin D have been linked to increased risk of asthma attacks in children and adults with asthma. There has been a growing interest in the potential role of vitamin D in asthma management because it might help to reduce upper respiratory infections (such as the common cold) that can lead to exacerbations of asthma.
Lead author of the Cochrane Review study, Professor Adrian Martineau from the Asthma UK Centre for Applied Research at QMUL’s Blizard Institute, said: “We found that taking a vitamin D supplement in addition to standard asthma treatment significantly reduced the risk of severe asthma attached, without causing side effects.”
The team of Cochrane researchers looked at seven trials involving 435 children and two studies, involving 658 adults, from a broad range of countries including Canada, India, Japan, Poland, the UK, and the US. The majority of people recruited to the studies had mild to moderate asthma, and a minority had severe asthma. Most people continued to take their usual asthma medication while participating in the studies.
Based largely on trials in adults, the researchers found that giving an oral vitamin D supplement reduced the risk of severe asthma attacks requiring hospital admission or emergency department attendance from 6 per cent to around 3 per cent. They also found that vitamin D supplementation reduced the rate of asthma attacks needing treatment with steroid tablets, but that vitamin D did not improve lung function or day-to-day asthma symptoms.
Professor Adrian Martineau added: “This is an exciting result, but some caution is warranted. 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 this questions are on-going, and results should be available in the next few months.”
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