Research Paper Title

Vitamin D₃ and Gargling for the Prevention of Upper Respiratory Tract Infections: A Randomized Controlled Trial.

Background

The researchers undertook a 2X2 factorial, randomised controlled trial (RCT) to assess whether vitamin D₃supplementation (10,000 international units per week) versus placebo and gargling versus no gargling could prevent viral, clinical upper respiratory tract infection (URTI) in university students.

Methods

600 students were randomised into 4 treatment arms:

1. vitamin D₃ and gargling,;
2. placebo and gargling,;
3. vitamin D₃ and no gargling; and
4. placebo and no gargling.

The students completed weekly electronic surveys and submitted self-collected mid-turbinate nasal flocked swabs during September and October in 2010 or 2011. Symptomatic students also completed an electronic symptom diary. The primary and secondary outcomes were the occurrence of symptomatic clinical URTI and laboratory confirmed URTI respectively.

Results

Of the 600 participants, 471 (78.5%) completed all surveys while 43 (7.2%) completed none; 150 (25.0%) reported clinical URTI. Seventy participants (23.3%) randomised to vitamin D₃ reported clinical URTI compared to 80 (26.7%) randomised to placebo (RR:0.79, CI₉₅:0.61-1.03, p = 0.09). 85 participants (28.3%) randomised to gargling reported clinical URTI compared to 65 participants (21.7%) randomised to the no gargling arm (RR:1.3, CI₉₅:0.92-1.57, p = 0.19). Laboratory testing identified 70 infections (46.7 per 100 URTIs). Vitamin D₃ treatment was associated with a significantly lower risk for laboratory confirmed URTI (RR: 0.54, CI₉₅:0.34-0.84, p = 0.007) and with a significantly lower mean viral load measured as log₁₀ viral copies/mL (mean difference: -0.89, CI_95: -1.7, -0.06, p = 0.04). Fewer students assigned to gargling experienced laboratory confirmed URTI, however this was not statistically significant (RR:0.82, CI₉₅:0.53-1.26, p = 0.36).

Conclusions

These results suggest that vitamin D₃ is a promising intervention for the prevention of URTI. Vitamin D₃ significantly reduced the risk of laboratory confirmed URTI and may reduce the risk of clinical infections.

Reference

Goodall, E.C., Granados, A.C., Luinstra, K., Pullenayegum, E. Coleman, B.L., Loeb, M. & Smieja, M. (2014) Vitamin D₃ and Gargling for the Prevention of Upper Respiratory Tract Infections: A Randomized Controlled Trial. BMF Infectious Diseases. 14(273).