title: Vitamin D3 and gargling for the prevention of upper respiratory tract infections: a randomized controlled trial.
abstract: BACKGROUND
  We undertook a 2X2 factorial, randomized controlled trial (RCT) to assess whether vitamin D3 supplementation (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
  We randomized 600 students 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. 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 600 participants, 471 (78.5%) completed all surveys while 43 (7.2%) completed none; 150 (25.0%) reported clinical URTI. Seventy participants (23.3%) randomized to vitamin D3 reported clinical URTI compared to 80 (26.7%) randomized to placebo (RR:0.79, CI95:0.61-1.03, p = 0.09). Eighty-five participants (28.3%) randomized to gargling reported clinical URTI compared to 65 participants (21.7%) randomized 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, CI95: -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.
  
  
  BACKGROUND
  
  
  
  BACKGROUND
  NCT01158560.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Goodall
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Granados
authors.forename: Kathy
authors.initials: K
authors.lastname: Luinstra
authors.forename: Eleanor
authors.initials: E
authors.lastname: Pullenayegum
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Coleman
authors.forename: Mark
authors.initials: M
authors.lastname: Loeb
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. smiejam@mcmaster.ca.
authors.forename: Marek
authors.initials: M
authors.lastname: Smieja
mesh_terms: D000293:Adolescent; D035843:Biomedical Research; D002762:Cholecalciferol / Q000627:therapeutic use*; D019587:Dietary Supplements; D005260:Female; D015438:Health Behavior; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D012141:Respiratory Tract Infections / Q000517:prevention & control*; D012306:Risk; D013334:Students; D014815:Vitamins / Q000627:therapeutic use*; D055815:Young Adult
chemical_list: D014815:Vitamins; D002762:Cholecalciferol