Comparison 2. Duration of the colds occurring when on regular ≥ 0.2 g/day vitamin C.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Duration of common cold symptoms (placebo group duration 100%)	31	9745	Mean Difference (IV, Fixed, 95% CI)	‐9.38 [‐12.86, ‐5.90]
1.1 Trials with adults	17	7215	Mean Difference (IV, Fixed, 95% CI)	‐7.72 [‐11.76, ‐3.69]
1.2 Trials with children	14	2530	Mean Difference (IV, Fixed, 95% CI)	‐14.19 [‐21.07, ‐7.31]