| Methods |
Double‐blind RCT. Regular supplementation trial. Duration 2 weeks |
| Participants |
Children attending ski school in Swiss Alps. 139 vitamin C; 140 placebo |
| Interventions |
1 g/d vitamin C |
| Outcomes |
Incidence (Analysis 1.1) and duration (Analysis 2.1) |
| Notes |
SD for duration was not published and the SD was calculated from the P value |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Randomised |
| Allocation concealment (selection bias) |
Low risk |
Double‐blind |
| Blinding of participants and personnel (performance bias)
All outcomes |
Low risk |
Double‐blind |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Double‐blind |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
|
| Vitamin C and placebo indistinguishable? |
Low risk |
"The placebo was indistinguishable from the 1‐gm ascorbic acid tablet" |
