Vitamin C supplementation effectiveness and risks

Scientific research challenges the long-held belief that high doses of Vitamin C can prevent the common cold. While popularised in the 1970s by chemist Linus Pauling, recent meta-analyses suggest that regular Vitamin C supplementation does not reduce the frequency of colds in the general population.

Studies indicate that for those who already take Vitamin C regularly, there may be a modest reduction in the severity of symptoms—approximately 8% to 15%—but it does not shorten the duration of mild symptoms significantly. Furthermore, starting supplementation after cold symptoms have already appeared appears to offer no meaningful benefit.

Medical experts warn against excessive intake. While the recommended daily allowance is relatively low (around 45mg in Australia), consuming doses exceeding 2,000mg can lead to adverse effects such as nausea, diarrhea, abdominal cramps, and an increased risk of kidney stones due to oxalate excretion. Experts recommend obtaining Vitamin C through natural food sources rather than high-dose supplements.