McFlu2 COLD3 Prevention: A Randomized, Placebo-controlled, Double Blind Trial of Vitamin D and Health Advice for the Prevention of Upper Respiratory Tract Infections in McMaster University Students

In the current study, we propose investigating the roles of vitamin D supplementation and of regular gargling to prevent URTI/ILI. Vitamin D may be an important factor in respiratory health. Observational studies have associated low serum 25(OH)D levels with more frequent and more severe respiratory infections. However, evidence is lacking that replacement of vitamin D decreases respiratory infections. Four interventional studies of vitamin D supplementation have noted a reduction in respiratory infections, with an estimated 5-25% reduction, but results were not statistically significant.

In Japanese populations, gargling has been found to significantly reduce the incidence of upper respiratory tract infections by approximately 35% (Satomura et al., 2005). This intervention has not been studied in different populations but may be a useful personal practice to reduce URTI.

We propose a 2X2 factorial, randomized, placebo-controlled trial of vitamin D/placebo and gargling/no gargling to study the effects of vitamin D supplementation and gargling on upper respiratory tract infections in McMaster students. This study will be conducted over two years, during September and October of each study year, to capture the natural peak in rhinovirus activity.