Low Vitamin D Levels Linked to Asthma
Study Shows Asthmatic Kids With Vitamin D Insufficiency Have Poorer Lung Function
March 3, 2010 (New Orleans) -- Many children with asthma have low blood
levels of vitamin D, and the insufficiency seems to place them at risk for more
In a study of 99 kids with asthma, 47% had vitamin D insufficiency. Compared
with children with normal levels of vitamin D levels, those with vitamin D
- Had poorer lung function
- Had higher levels of immunoglobulin E (IgE), an immune system protein the
body makes in response to allergens that tells you the likelihood that you're
- Were more likely to need inhaled and oral steroid medications to reduce
airway inflammation and mucus production
- Were more likely to need long-acting beta-agonist drugs that relax muscles
in the lung's airways, improving a patient's ability to breathe freely and
reducing asthma symptoms.
Further studies in the lab showed that vitamin D has an anti-inflammatory
effect on cells and enhances the activity of inhaled steroids.
About 21 million Americans suffer from asthma, which is caused by
inflammation and swelling of the airways. The inflammation, in turn, can cause
excessive mucus production and narrowing of the airways, resulting in asthma
symptoms such as shortness of breath, coughing, and wheezing.
The findings were presented at the American Academy of Allergy, Asthma &
Immunology annual meeting.
The study doesn't prove cause and effect. And it's not clear whether low
vitamin D causes more severe asthma that requires treatment or whether more
severe asthma lowers vitamin D levels, says study researcher Daniel A. Searing,
MD, of National Jewish Health in Denver.
Also still unknown is whether vitamin D supplements would improve asthma
control and lower the need for medication, he tells WebMD.
Still, a number of studies now suggest that low vitamin D levels are
associated with allergies and asthma, says James Gern, MD, vice chair of the
committee that chose which studies to highlight at the meeting and professor of
pediatrics at the University of Wisconsin in Madison.
If a person has vitamin D insufficiency, "we need to correct it anyway. So
it will be interesting to see if the supplements help improve asthma symptoms,"
he tells WebMD. Gern was not involved with the work.
In the study, vitamin D insufficiency was defined as levels below 30
nanograms per milliliter of blood.