Vitamin C Fails to Prevent Colds, Cuts Severe Symptoms by About 10%
Updated
Updated · ScienceDaily · Aug 27
Vitamin C Fails to Prevent Colds, Cuts Severe Symptoms by About 10%
2 articles · Updated · ScienceDaily · Aug 27
Summary
Regular vitamin C supplements do not stop most people catching colds, but they may shorten severe symptoms by about 10%—roughly 12 hours in a five-day severe cold.
A 2023 meta-analysis of 10 placebo-controlled trials covering 2,736 healthy people found a 15% reduction in severe symptoms among those taking at least 1,000 mg daily, while mild symptoms were unchanged.
A 2013 review similarly found no drop in cold incidence in the general population, though athletes and military personnel saw fewer colds and children and adults had symptom severity reduced by 8% to 14%.
Timing matters: taking vitamin C only when symptoms start showed no benefit, so any effect requires regular use before illness begins.
High doses above 1,000 mg a day can bring risks including gastrointestinal problems, kidney stones, increased iron absorption and drug-treatment interactions, undercutting Linus Pauling's long-popular 1,000-2,000 mg advice.