| Methods |
Double‐blind RCT. Cross‐over regular supplementation trial. Duration 2 + 2 weeks. In the first 2 weeks 25 participants received vitamin C and 18 placebo. As participants became ill they were removed from the trial and 3 people withdrew. In the second period, 18 received placebo and 8 vitamin C |
| Participants |
Swedish army males. 33 vitamin C; 33 placebo |
| Interventions |
2 g/d vitamin C for 2 weeks |
| Outcomes |
Incidence (Analysis 1.1) |
| Notes |
— |
| 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? |
Unclear risk |
? |
