Vitamin D 'halves risk of severe asthma attacks', suggests Cochrane review
Vitamin D supplements are ‘likely’ to reduce severe asthma exacerbations when taken alongside standard medication, according to the authors of a new gold-standard review.
The researchers, from the Queen Mary University of London, found that giving an oral vitamin D supplement signficantly cut the risk of severe asthma exacerbations requiring hospital admission or emergency department attendance from 6% to around 3%.
The authors of the Cochrane meta-analysis of seven randomised trials and two studies also found that the study participants given vitamin D experienced fewer asthma attacks needing treatment with oral steroids.
The RCGP said the study was ‘encouraging’, but it was ‘too early’ to recommend regular vitamin D supplementation to patients with asthma.
In July, Public Health England recommended that everyone should consider taking vitamin D tablets in winter on a daily basis. But a Pulse investigation earlier this year revealed that the annual cost of prescribing vitamin D now £85m, with some GPs saying prescribing is already ‘out of control’ and is costing millions in GP and nurse time.
This new analysis included 435 children and 658 adults with a clinical diagnosis of asthma. It concluded: ‘Meta-analysis of a modest number of trials in people with predominantly mild to moderate asthma suggests that vitamin D is likely to reduce both the risk of severe asthma exacerbation and healthcare use.
‘Administration of vitamin D was associated with a statistically significant reduction in the rate of asthma exacerbations treated with systemic corticosteroids’.
The study suggested that, given that the majority of asthma exacerbations are precipitated by viral upper respiratory infections, ‘it seems likely that vitamin D’s mechanism of action relates either to prevention of such infections, or to interruption of pathways by which such events trigger exacerbations’.
Lead author Professor Adrian Martineau said that the results were ‘exciting’: ‘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.’
However he added: ‘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 ongoing, and results should be available in the next few months.’
Dr Imran Rafi, chair of clinical innovation and research at the RCGP, said the 'encouraging' results needed further work before GPs could put them into practice.
He added: 'We look forward to seeing the results of further rigorous clinical trials both in adults and children so that we gain a better understanding of this potential method of treatment.'