Taking oral vitamin D supplements in addition to standard asthma medication could halve the risk of asthma attacks requiring hospital attendance, according to research led by Queen Mary University of London (QMUL).
Asthma affects more than 300 million people worldwide and is estimated to cause almost 400,000 deaths annually. 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.
Overall, the researchers found that vitamin D supplementation resulted in:
- a 30 per cent 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.
- a 50 per cent reduction in the risk of experiencing at least one asthma attack requiring Accident and Emergency Department attendance and/or hospitalisation - from 6 per cent of people experiencing such an event to 3 per cent.
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.
Lead researcher Professor Adrian Martineau said: "These results add to the ever growing body of evidence that vitamin D can support immune function as well as bone health. 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 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.
Professor Hywel Williams, Director of the NIHR Health Technology Assessment Programme, said: "The results of this NIHR-funded study brings together evidence from several other studies from over the world and is an important contribution to reducing uncertainties on whether Vitamin D is helpful for asthma - a common condition that impacts on many thousands of people worldwide."
Dr David Jolliffe from QMUL, first author on the paper, added: "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 generalised to these patient groups at this stage. 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."
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Notes to the editor
Research paper: 'Vitamin D supplementation to prevent asthma exacerbations: systematic review and meta-analysis of individual participant data'. David A Jolliffe, Lauren Greenberg, Richard Hooper, Christopher Griffiths, Carlos Camargo Jr, Conor Kerley, Megan Jensen, David Mauger, Iwona Stelmach, Mitsuyoshi Urashima, Adrian Martineau. The Lancet Respiratory Medicine.
The article can be found here after embargo lifts: http://www.thelancet.com/journals/lanres/article/PIIS2213-2600(17)30306-5/fulltext?elsca1=tlxpr
About Queen Mary University of London
Queen Mary University of London (QMUL) is one of the UK's leading universities with 23,120 students representing more than 160 nationalities.
A member of the Russell Group, we work across the humanities and social sciences, medicine and dentistry, and science and engineering, with inspirational teaching directly informed by our research. In the most recent national assessment of the quality of research, we were placed ninth in the UK amongst multi-faculty universities (Research Excellence Framework 2014).
As well as our main site at Mile End - which is home to one of the largest self-contained residential campuses in London - we have campuses at Whitechapel, Charterhouse Square, and West Smithfield dedicated to the study of medicine and dentistry, and a base for legal studies at Lincoln's Inn Fields.
Queen Mary began life as the People's Palace, a Victorian philanthropic project designed to bring culture, recreation and education to the people of the East End. We also have roots in Westfield College, one of the first colleges to provide higher education to women; St Bartholomew's Hospital, one of the first public hospitals in Europe; and The London, one of England's first medical schools.
Today, as well as retaining these close connections to our local community, we are known for our international collaborations in both teaching and research. QMUL has an income of £400m and a research income worth £137m (2015/16) and generates employment and output worth in excess of £700m to the UK economy each year.
About the National Institute for Health Research
The National Institute for Health Research (NIHR): improving the health and wealth of the nation through research.
Established by the Department of Health, the NIHR:
- funds high quality research to improve health
- trains and supports health researchers
- provides world-class research facilities
- works with the life sciences industry and charities to benefit all
- involves patients and the public at every step
For further information, visit the NIHR website http://www.