Vitamin D supplements have the potential of halving the risk of severe asthma attacks, a new study by researchers at Queen Mary University of London (QMUL) reveals.
Asthma is one of the most common diseases affecting more than 300 million people worldwide. It is also estimated at as many as 400,000 deaths annually are caused by asthma. Asthma deaths arise primarily during episodes of acute worsening of symptoms, known as attacks or ‘exacerbations’, which are commonly triggered by viral upper respiratory infections.
Vitamin D is thought to protect against such attacks by boosting immune responses to respiratory viruses and dampening down harmful airway inflammation.
The new study, funded by the National Institute for Health Research, and published in The Lancet Respiratory Medicine, collated and analysed the individual data from 955 participants in seven randomised controlled trials, which tested the use of vitamin D supplements.
Vitamin D supplementation was found to be safe at the doses administered. 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.
The team’s use of individual participant data also allowed them to query the extent to which different groups respond to vitamin D supplementation, in more detail than previous studies.
In particular, vitamin D supplementation was found to have a strong and statistically-significant protective effect in participants who had low vitamin D levels to start with. These participants saw a 55 per cent 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.