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Vitamin D supplementation reduces risk of asthma exacerbations

Patients with asthma who supplement with vitamin D are less likely to have an exacerbation requiring treatment with corticosteroids than those who do not take vitamin D.

A review of seven randomised trials found that asthma patients are 26% less likely to suffer an exacerbation requiring steroid treatment if they supplement with vitamin D, compared to patients who take a placebo.

The effect was more pronounced in those who had asthma along with a lower baseline level of vitamin D. Patients with levels below 25nmol/l were 67% less likely to experience an exacerbation requiring treatment, but those with vitamin D levels above 25nmol/l had no significant reduction in the risk of exacerbation. 

Dose equivalents of of 2,000IU per day had a significantly greater effect at reducing the risk of exacerbations requiring treatment, compared to doses below this level.

The UK-led research looked 955 patients, aged between six and 85 years old, across seven trials.

The results add to the growing weight of research supporting vitamin D supplementation in patients with asthma, while also showing a slightly enhanced effect in patients who already have low baseline levels.

Lead author Dr David Jolliffe, a researcher a Queen Mary University of London, said: ‘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.’

But in the paper, the group added that ‘vitamin D supplementation represents a potentially cost-effective strategy’ for reducing mortality in asthma patients.

Lancet 2017, online 3 Oct