Vitamin D Does Not Prevent Colds in Asthma Patients

The results of a recent study indicate that patients with asthma cannot reduce their risk of developing the common cold by taking vitamin D supplements. The study, published in the American Thoracic Society’s American Journal of Respiratory and Critical Care Medicine, randomly assigned 408 patients, with mild to moderate asthma, to receive either vitamin D supplementation (100,000 IU once, followed by 4000 IU daily) or placebo for 28 weeks. The research team found that the achievement of vitamin D sufficiency among patients who received the supplements made no difference in either the number or the severity of colds compared with those who were given placebo; in fact, African-American participants, who received vitamin D supplements, experienced more colds than those in the placebo group.

The researchers were surprised by these results, as they had previously published a study in which the achievement of vitamin D sufficiency, among deficient patients, was associated with a 40% reduction in asthma exacerbations. One possible explanation the authors gave for their latest finding was that patients with asthma who had low vitamin D levels are more likely to experience an inflammatory response triggered by upper respiratory infections; this response could then reduce the risk of lower airway infections.

Although the study authors noted a number of benefits associated with the use of vitamin D in patients with asthma, they maintained that supplementation with the vitamin should not be recommended for the prevention of colds.