An analysis of seven previous studies suggests vitamin D may help reduce asthma attacks and the need for steroid treatment among patients, but researchers say more work is needed to determine whether it will help all or just some subgroups of patients. Photo by vchal/Shutterstock
LONDON, Sept. 6 (UPI) -- Low levels of vitamin D have been suspected as increasing the risk for asthma attacks, and a new review of studies suggested the vitamin can significantly reduce attacks among some groups of patients.
Vitamin D supplements cut the incidence of asthma attacks requiring hospitalization in half and reduced the need for steroid treatments in some cases, according to the analysis published in The Cochrane Library.
Previous studies have linked low levels of vitamin D in children to higher incidence of severe asthma, however there have not been large trials of supplements to determine its usefulness in the condition.
Even with the efficacy shown among some patients in the new study, researchers involved with the research caution that vitamin D is not necessarily a replacement for asthma medications.
"We don't want people giving up taking their asthma treatment," Dr. Adrian Martineau, a researcher at Queen Mary University of London, told The BBC, adding that he doesn't "think it would be appropriate to just start taking vitamin D without knowing whether you have vitamin D deficiency or not and we don't yet know what the threshold of vitamin D is below which you will have a benefit."
For the study, the researchers identified seven studies with 435 children and two trials with 658 adults in their analysis which ranged from four to 12 months long. Most patients in the studies had mild to moderate asthma, and all participants continued to take their usual asthma medications.
The researchers found that an oral vitamin D supplement reduced the risk of severe asthma attacks requiring hospitalization or emergency treatment from 6 percent to about 3 percent. The analysis also showed the rate of asthma attacks requiring steroid treatment decreased from 0.44 attacks per person per year to 0.28.
With the benefits to severe asthma patients, however, the researchers also note vitamin D did not improve lung function or day-to-day asthma symptoms. Most of the benefit of vitamin D was also seen among adult patients, the researchers report.
"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," Martineau said in a press release. "This is an exciting result, but some caution is warranted."
He said the fact that most patients in the studies had mild or moderate asthma, that further trials are needed in both children and adults with severe asthma. He said that the relevance of a patient having low vitamin D levels requires more research on whether a supplement could be a viable treatment option.
"Further analyses to investigate this question are on-going, and results should be available in the next few months," Martineau said.