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 The researchers say the results - if confirmed by larger studies -
might help the many people who sometimes have troublesome asthma
symptoms even though they use medication.
“It does build some on the growing amount of data that shows vitamin
D might help those affected by asthma,” Dr. Mario Castro, who was
not involved in the study, told Reuters Health.
But Castro, a professor of Pulmonary and Critical Care Medicine at
Washington University School of Medicine in St. Louis, Missouri,
pointed out that the researchers only measured patients’ lung
function, and not whether or not their symptoms improved.
“Given that vitamin D is a relatively benign supplement,” the small
improvement in lung function “would be worthwhile if it was
confirmed with other improvements in asthma control,” he said, such
as fewer symptoms or a reduced need for medication.
About one in 12 individuals, or 25 million people, have asthma in
the U.S. alone. In the last decade, the number of people with asthma
has grown by about 15 percent.
Higher rates of asthma in northern climates have led some
researchers to suspect that less sunlight - and therefore less
vitamin D - could be playing a role. Several studies have shown a
link between low vitamin D levels and asthma.
The new study, by Dr. Saba Arshi at the Medical University of Tehran
and colleagues, involved 130 children and adults with
mild-to-moderate asthma.
Everyone received asthma medication in a dry powder inhaler (budesonide,
sold in the U.S. as Pulmicort, or budesonide plus formoterol, sold
in the U.S. as Symbicort).
In addition, half the group was randomly chosen to receive high
doses of vitamin D for six months. The first dose, 100,000 units,
was given by injection; then patients were instructed to take 50,000
units orally once a week.
After eight weeks, when the researchers measured the amount of air
patients could exhale in one second, both groups had improved to
roughly the same extent. But after 28 weeks, that amount had
improved by about 20 percent in the patients who received vitamin D
supplements, versus about 7 percent among those who only used the
inhaler.
The authors did not respond to questions about the study, which was
published in Annals of Allergy, Asthma and Immunology.
Castro thinks the patients in the study weren’t particularly
deficient in vitamin D.
“This is another weakness as they enrolled patients with normal
vitamin D levels, so (they’re) unlikely to see a treatment effect,”
Castro said.
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He would not recommend that patients with asthma take vitamin D
supplements based on this study and one of his own studies, though
his research found some people with deficient levels improved after
supplementation.
Dr. Doug Brugge, a professor of public health and community medicine
at Tufts School of Medicine in Boston, said he thought the study
added to the field of asthma and vitamin D research.
“I think it adds some evidence that vitamin D may be beneficial in
terms of treating asthma, which in turn contributes some evidence
that vitamin D is a factor in asthma,” Brugge, who wasn’t involved
in the study, told Reuters Health.
He noted that most asthma research has focused on children, but this
one included adults. “There really is a need for more research on
asthma in adults,” he said.
But Brugge, who has studied the possible environmental causes of
childhood asthma, said the study would have been more convincing if
researchers had checked whether patients took their medication as
prescribed (other than asking by phone) and included any exposure to
environmental triggers of asthma.
“It leaves a little doubt in my mind . . . what if the intervention
group was adhering to the medication more than the control group? I
think it’s unlikely but it would have been nice to see that a little
more clearly addressed,” said Brugge.
“Adherence is a big problem,” said Brugge, referring to medication
use in general. “Non-adherence is more common than adherence.”
Brugge too thinks more studies are needed before anyone can assume
that vitamin D would help people with asthma.
“I think it’s a reasonable hypothesis and their study and some other
studies provide evidence it might be true. But I don’t think it’s
proven yet,” said Brugge.
SOURCE: http://bit.ly/XvqH39
Annals of Allergy, Asthma and Immunology, online August 2, 2014.
[© 2014 Thomson Reuters. All rights
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