Vitamin C Fails to Prevent Colds, Cuts Severe Symptoms About 10%

1 articles · Updated · SciTechDaily · Aug 24

A 2023 meta-analysis of 10 placebo-controlled trials involving 2,736 people found regular vitamin C use reduced severe cold symptoms by 15% but did not shorten mild symptoms.
Broader evidence still shows no drop in cold risk for the general population, and taking vitamin C only when symptoms begin offers no benefit.
A 2013 meta-analysis found lower daily doses around 200 mg did not prevent colds overall, though athletes and military personnel saw fewer infections and children and adults had symptom severity reduced by 8% to 14%.
Linus Pauling's 1970 advice to take 1,000 to 2,000 mg daily helped popularize the belief, but later critics cited mathematical errors and weak trials behind his claims.
High-dose use above 1,000 mg a day can cause gastrointestinal problems, raise kidney stone risk and interact with some treatments, even though fewer than 4% of Australians are vitamin C deficient.