Vitamin D may halve asthma attacks

For asthma sufferers, a severe attack can be life-threatening. But now, researchers have found that a simple vitamin supplement could significantly reduce that risk.

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% 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% reduction in the risk of experiencing at least one asthma attack requiring accident & emergency department attendance and/or hospitalisation — from 6% of people experiencing such an event to 3%.

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.”

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