Study: Vitamin D Doesn't Protect Asthma Patients' from Catching a Cold

A team led by researchers from the University of Wisconsin and Pennsylvania State University finds that vitamin D supplements diminish neither the number nor severity of colds in asthma patients.

According to the authors, previous studies involving vitamin D and colds—many of which primarily included healthy patients—have garnered mixed results. In an effort to evaluate this relationship among those for whom colds carry more risk, the investigators followed asthma patients who were undergoing inhaled corticosteroid (ICS) tapering, testing the hypothesis that vitamin D may strengthen the effectiveness of the ICS.

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Overall, 408 adults with mild-to-moderate asthma and either insufficient or deficient vitamin D levels were enrolled in the multi-center AsthmaNet Vitamin D Add-on Therapy Enhances Corticosteroid Responsiveness (VIDA) trial. Enrollees demonstrated asthma symptoms despite undergoing low-dose ICS therapy. The researchers randomized patients to receive either vitamin D supplementation or placebo for 28 weeks, with neither patients nor their physicians aware of which the patients received.

In that span, 203, or just about half, of the patients experienced at least 1 cold, according to the authors, who note that the severity of their colds was measured by the Wisconsin Upper Respiratory Symptom Survey-21 (WURSS-21). In analyzing the results of the 82% of patients receiving supplements, the researchers found that those in this group achieved vitamin D sufficiency within 12 weeks. Achieving sufficiency, however, had no impact on the number or severity of colds patients in this group experienced, according to the authors.

Ultimately, the study findings suggest that “replacement of vitamin D levels does not affect the severity of colds, but may increase the frequency of cold symptoms in select groups of patients with asthma, particularly when the dose of ICS is being reduced,” the authors wrote.

These results “do not support the use of vitamin D supplementation for the purpose of reducing cold severity or frequency” in patients with mild-to-moderate asthma who are undergoing an ICS dose reduction, the investigators added.

—Mark McGraw


Denlinger L, King T, et al. Vitamin D Supplementation and the Risk of Colds in Patients with Asthma. AJRCCM. 2015.