For anyone with asthma, preventing attacks of wheezing, coughing, chest tightness and shortness of breath is a top priority.

Might vitamin D help?

This study

The researchers analyzed data from nine studies, involving 1,093 children and adults with asthma, most diagnosed with mild to moderate cases. The participants had been randomly assigned to take an oral vitamin D supplement (500 to 1,200 International Units) or a placebo daily, along with their usual asthma medication.

After four to 12 months, those who took vitamin D experienced fewer asthma attacks requiring treatment with corticosteroids than did people who took a placebo. The vitamin D group also was 61 percent less likely than the placebo group to have a severe asthma attack leading to an emergency room visit, hospitalization or both. The effect of vitamin D on severe asthma attacks was seen mostly among adults. Taking vitamin D had essentially no effect on lung function or day-to-day asthma symptoms.

Who may be affected

People with asthma, who number about 25 million, or 1 in every 12, U.S. residents.

Asthma symptoms, called exacerbations, occur when a person’s airways narrow, swell and produce extra mucus. No cure exists, but symptoms usually can be controlled with medication, aided by awareness of what triggers a person’s attacks. Severe attacks can be life-threatening.

Caveats

Whether any participants had a vitamin D deficiency was not included in the data and may have affected the results. Dosage amount, dosage schedules and study durations varied among the studies. The analysis did not determine an optimum dose of vitamin D for beneficial results.

Find this study

Online in the Cochrane Library (cochranelibrary.com).

Learn more

Information on asthma is available at nhlbi.nih.gov/health and lung.org (click on “Lung Health & Diseases”).

The research described in Quick Study comes from credible, peer-reviewed journals.