Don’t rely on vitamin C to prevent colds
Original: eternity4719 · source details
Original author: eternity4719 · Chinese source: · English adaptation: parveen0029. Translation and grade notes ↗
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Cost and benefit at a glance
- Check the cost Cost ↓
- Each effervescent tablet costs roughly 1–2 yuan; annual expense ranges from 300 to 700 yuan.
- Then the source benefit Benefit ↓
- Cochrane’s pooled analysis of 29 trials with 11306 participants indicates that regular vitamin C consumption does not meaningfully lower overall cold incidence; the risk ratio is 0…
In plain terms
A combined analysis of 29 controlled trials shows that daily vitamin C intake hardly reduces the likelihood of catching a cold. Taking it after symptoms appear also yields inconsistent results. It can shorten the duration of a cold by about 8%, which equals roughly half a day of reduced discomfort. The absolute number of people who benefit from this effect is 500. Whether this half-day of relief is worth spending several hundred yuan per year is a personal calculation. Marathon runners and soldiers stationed in cold climates form the exception: among them, daily vitamin C intake cuts cold incidence roughly in half.
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Cost: what it takes
Each effervescent tablet costs roughly 1–2 yuan; annual expense ranges from 300 to 700 yuan.
Benefit: what the source reports
Cochrane’s pooled analysis of 29 trials with 11306 participants indicates that regular vitamin C consumption does not meaningfully lower overall cold incidence; the risk ratio is 0.97 (95% CI 0.94–1.00). For trials where vitamin C was taken after cold onset, results varied widely — some showed benefit while others did not. Among participants who took it regularly, the average cold duration decreased by 8% in adults (95% CI 3%–12%) and 14% in children (7%–21%). Marathon runners, skiers, and soldiers in cold environments again represent the exception: five trials with 598 participants demonstrated that vitamin C intake reduced cold incidence by half (RR 0.48; 95% CI 0.35–0.64). Its perceived value stems largely from its low cost, pleasant taste, and the long-standing belief that vitamin C prevents colds.
Conditions, limits and disagreements
Controversy: The same review confirms that regular vitamin C intake does shorten cold duration — by 8% in adults (3%–12%) and 14% in children (7%–21%), equating to roughly half a day of reduced illness per cold episode. Marathon runners, skiers, and soldiers in cold climates remain the exception; five trials involving 598 subjects show a 50% reduction in cold incidence (RR 0.48; 95% CI 0.35–0.64). The vast majority of people do not fall into these categories.
Original references
Original bibliographic titles and links are preserved; some titles are in Chinese.
Hemilä H, Chalker E (2013). Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev. https://doi.org/10.1002/14651858.CD000980.pub4
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