Running low on vitamin D could increase the severity of asthma, a new study suggests. Previous lab tests have shown that vitamin D can influence airway-cell response to inhaled steroids, but this is the first human-based study on vitamin D and asthma severity.

Researchers recruited 616 asthmatic children from Costa Rica (a country with a high prevalence of asthma) and studied their lung function, vitamin D levels, and allergic markers. Study results indicated that children with lower vitamin D levels were more likely to have been hospitalized for asthma in the previous year, as well as to have used more inhaled corticosteroids (powerful drugs used to reduce inflammation in the airways). Study members with lower vitamin D levels also tended to have several markers of allergy, such as dust-mite sensitivity.

Increasingly common in the United States, deficiency in vitamin D could also contribute to certain cancers, osteoporosis, periodontal disease, and rheumatoid arthritis.

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