Vitamin C does not prevent the common cold for the general population, though regular intake can modestly reduce the severity and duration of symptoms by about 10% to 15%. The widespread belief that high-dose vitamin C prevents colds originates largely from chemist Linus Pauling's 1970 bestselling book, which recommended daily doses of 1,000 to 2,000 milligrams based on limited and widely criticized evidence. Modern meta-analyses, including a 2023 study involving 2,736 participants, show that taking vitamin C only after cold symptoms start has no therapeutic benefit. To achieve any reduction in symptom severity, individuals must consume vitamin C regularly and preventatively before falling ill, with specific populations such as athletes and military personnel showing occasional reductions in cold frequency. Exceeding the recommended daily intake of 45 mg for Australian adults by consuming high-dose supplements above 1,000 mg daily far exceeds nutritional needs. Less than 4% of Australians are actually deficient in vitamin C, and obtaining sufficient amounts is easily accomplished through dietary sources like half an orange or a few florets of broccoli. Consuming high doses of vitamin C continually poses health risks, including gastrointestinal discomfort, increased risk of kidney stones from oxalate excretion, enhanced iron absorption dangerous for individuals with hemochromatosis, and negative drug interactions with chemotherapy, radiation, and statins. Consumers should consult their general practitioner before starting supplements and keep daily doses below 1,000 mg.
