Comparison 1. Incidence of colds while taking ≥ 0.2 g/day vitamin C regularly.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Proportion of participants developing ≥ 1 cold episodes during the trial	29	11306	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.92, 0.98]
1.1 All eligible trials with exception of subgroup removed below	24	10708	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.94, 1.00]
1.2 Short‐term exposure to severe physical stress and/or cold	5	598	Risk Ratio (M‐H, Fixed, 95% CI)	0.48 [0.35, 0.64]