Thursday, April 23, 2009

Vitamin D Insufficiency and Asthma

A new study is being reported on which provides evidence for a link between vitamin D insufficiency and asthma severity.

In Costa Rica, more than 600 children had their serum levels of Vitamin D tested, and these were inversely linked to several indicators of allergy and asthma severity. It seems that hospitalizations for asthma, use of inhaled steroids and total IgE levels were both shown to be much higher whenever Vitamin D was insufficient. This study will appear in the first issue for May of the American Journal of Respiratory and Critical Care Medicine and is linked to the headline of this post.

Costa Rica is a country known to have a high prevalence of asthma. Juan Celedón, M.D. and his colleague Augusto Litonjua, M.D. of Harvard Medical School recruited 616 children with asthma to be assessed for allergic markers, including both allergen-specific and general sensitivity tests, and assessed for lung function and circulating vitamin D levels.

They found that children with lower vitamin D levels were significantly more likely to have been hospitalized for asthma in the previous year; these youngsters also tended to have airways with increased hyperreactivity and were likely to have used more inhaled corticosteroids. They were also significantly more likely to have several markers of allergy, including dust-mite sensitivity.

“This study suggests that there may be added health benefits to vitamin D supplementation” said Dr. Celedón. Current recommendations for optimal vitamin D levels are geared toward preserving bone health, such as preventing rickets in children and osteoporosis in adults. But these levels may not be sufficient to deal with issues of allergies and asthma.

“This study also provides epidemiological support for a growing body of in vitro evidence that vitamin D insufficiency may worsen asthma severity, and we suspect that giving vitamin D supplements to asthma patients who are deficient may help with their asthma control” wrote the authors, noting that a clinical trial should be the next step in this research.

“Whether vitamin D supplementation can prevent the development of asthma in very young children is a separate question, which will be answered by clinical trials that are getting under way,” he said.


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