Vitamin D pills can halve the risk of serious asthma attacks according to a major review of research into the impact the supplements have on the condition.
People with mild or moderate asthma who took the vitamin with their normal medicine had fewer attacks that required hospital treatment than those who went without, scientists found.
The risk of severe attacks fell from 6% to 3% in patients who had a vitamin D boost for six months to a year. The supplements cut the frequency of attacks too, with cases needing steroid treatment falling from one per person every two or so years, to one every four years.
Half of all asthma patients will at some point have an attack that needs treating with oral steroids such as prednisolone, while a quarter will end up in hospital emergency departments. One in eight will have such serious attacks that they are admitted to hospital for further care.
“There were some pretty striking positive findings,” said Adrian Martineau, a professor of respiratory infection who led the review at Queen Mary, University of London. “Asthma attacks cause 185 hospital admissions and three deaths each day in the UK, so this is a major problem for society.”
More than five million people in the UK, and 334 million globally, are affected by asthma which causes wheezing, coughing, tightness in the chest, and shortness of breath.
The review for the Cochrane library drew on results from seven published trials on 435 children, and a further two trials on 658 adults. Most of the patients had mild to moderate asthma, meaning they had symptoms at least two days a week, but their daily routine was not seriously affected. Nearly all kept taking their normal asthma medicine on top of the vitamin D supplements.
While the trials found that a daily dose of 25 to 50 micrograms reduced the risk of serious attacks, the evidence was largely from adults. “We need more trials specifically focusing on children and also specifically focusing on adults with severe asthma to see if those patient groups could benefit,” Martineau said.
In July, Public Health England recommended that everybody in Britain over the age of one consider taking a 10 microgram daily supplement of vitamin D, particularly over the autumn and winter when sunlight levels are low. The body makes vitamin D when sunlight falls on the skin, but people who cover up outside, and those who are housebound can struggle to make enough.
It is not clear how vitamin D helps asthma patients, but supplements may work by boosting the immune system’s defences against respiratory infections, such as the common cold, which are the main triggers for serious asthma attacks. The vitamin also seems to keep inflammation under control.
“You can think of vitamin D almost as a designer drug because it has these two actions, the first being to boost immunity to infections and the second to dampen down inflammation,” said Martineau.
One question scientists hope to answer in the next few months is whether supplements only benefit asthma patients with low levels of vitamin D. “At the moment we just don’t have the evidence to say who are those who are going to benefit and how low their vitamin D has to be in order to benefit,” Martineau said. “We don’t want people to stop taking their asthma medication and start taking vitamin D instead,” he added.
The findings come as scientists report impressive trial results for a drug that cuts asthma attacks in patients with the most severe form of the disease. Two trials in more than 2,500 people showed that a year’s course of benralizumab injections reduced asthma attacks by a third to a half, according to The Lancet.
Samantha Walker at Asthma UK said the new drug offered “genuine hope” for people in the UK who had a type of asthma that does not respond to standard treatments. “These people struggle to breathe every day, restricting their ability to carry out everyday activities such as going to work or school and severely affecting their quality of life,” she said.
Vitamin D supplements could halve risk of serious asthma attacks
