Extra Dose of Vitamin C Based on a Daily Supplementation Shortens the Common Cold: A Meta-Analysis of 9 Randomized Controlled Trials.
Level 1 - systematic review of randomized trials
Meta-analysis of 9 randomized controlled trials
PubMed 30069463 · doi:10.1155/2018/1837634
What was done
A meta-analysis of 9 English-language randomized placebo-controlled trials searched across PubMed, Cochrane Library, Elsevier, CNKI, VIP, and WANFANG databases. The study evaluated whether extra therapeutic doses of vitamin C administered at the onset of a common cold in individuals already taking daily routine supplementation reduced illness severity and duration.
What was found
Extra vitamin C at cold onset reduced illness duration (mean difference [MD] = -0.56, 95% CI [-1.03, -0.10], P = 0.02) and time spent confined indoors (MD = -0.41, 95% CI [-0.62, -0.19], P = 0.0002). It also reduced symptom scores for chest pain (MD = -0.40, 95% CI [-0.77, -0.03], P = 0.03), fever (MD = -0.45, 95% CI [-0.78, -0.11], P = 0.009), and chills (MD = -0.36, 95% CI [-0.65, -0.07], P = 0.01).
Why it matters
It addressed whether acute therapeutic dose escalation offers additive relief during an active cold for individuals already taking daily maintenance vitamin C.
Limits
The publication has been retracted, fundamentally undermining the reliability of its findings. Additionally, the abstract does not report the total participant count, exact dosing regimens, or units of measurement for duration and symptom scales.
Cited by
- partial A meta-analysis of nine trials found that combining prophylactic vitamin C with therapeutic doses reduced cold symptom duration by about half a day, whereas therapeutic dosing initiated only at symptom onset had no effect.