| Methods |
Double‐blind RCT. Regular supplementation trial. Duration 21 days prior to the race |
| Participants |
South Africa. Ultra marathon runners. 44 vitamin C; 47 placebo |
| Interventions |
0.5 g/d vitamin C |
| Outcomes |
Incidence (Analysis 1.1) and duration (Analysis 2.1) |
| Notes |
SD for duration was not published and it was estimated as SD = mean |
| 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 |
"tablets of similar appearance" |
