A Cochrane review has provided more robust evidence that adding vitamin D supplements to routine asthma management plans may benefit patients.
However more research is required to confirm optimal dosing and the likely benefit in various patient sub-groups, co-author Dr Megan Jensen told the limbic.
Dr Jensen, an accredited practising dietitian in the University of Newcastle’s Priority Research Centre Grow Up Well, said many patients, especially families of children with asthma, would welcome vitamin D supplements.
“An easy-to-take nutritional supplement that can provide further benefit on top of normal maintenance therapy for asthma will be acceptable to a lot of families,” she said.
“However this a fat-soluble group of vitamins that is stored in the body and can have toxic effects at excessive levels.
We can’t yet recommend patients without a known deficiency take high doses of vitamin D.”
The meta-analysis comparing vitamin D versus placebo in more than 1,000 adults and children found supplementation was associated with fewer severe asthma attacks requiring oral corticosteroids (0.44 v 0.28 asthma attacks/person/year) and fewer ED visits or hospital admissions (6.3 v 2.5 attendances/100 participants).
There was no significant difference between the groups in either lung function tests or day-to-day asthma symptoms.
The authors said likely mechanisms of action for vitamin D included a role in preventing respiratory infections that trigger asthma attacks, anti-inflammatory activity or enhancing responsiveness to inhaled corticosteroids.
Dr Jensen said some clinicians in Canada, where they have harsh winters and low exposure to UVB rays, were already supplementing children with vitamin D.
However the Cochrane review did not have sufficient data to determine if the beneficial effects were driven by correction of sub-optimal levels of vitamin D.
“We don’t know yet if people with low levels of vitamin D respond better, if asthma severity makes a difference or the contribution of vitamin D receptor polymorphisms,” she added.