Review Article
[Retracted] Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials
Table 2
Cochrane collaboration’s tool for assessing risk of bias in the comparison of vitamin C versus placebo.
| Studies | Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective reporting | Other bias |
| Anderson [30] 1972 | low risk | low risk | low risk | low risk | low risk | low risk | unclear | Anderson [31] 1975 | low risk | low risk | low risk | low risk | low risk | low risk | unclear | Audera [32] 2001 | low risk | low risk | low risk | low risk | low risk | low risk | unclear | Elwood [33] 1977 | unclear | low risk | low risk | low risk | low risk | low risk | unclear | Tyrrell [34] 1977 | unclear | low risk | low risk | low risk | low risk | low risk | unclear | Lewib [35] 1975 | unclear | unclear | low risk | unclear | low risk | low risk | unclear | Karlowski [36] 1975 | low risk | unclear | low risk | low risk | low risk | low risk | unclear | Cowan [37] 1950 | unclear | unclear | unclear | unclear | low risk | low risk | unclear |
|
|