Recently, a friend of mine explained how he was popping crazy amounts of vitamin C supplements in hope of curing his latest episode with the cold. This inspired me to search through a part of a thesis I wrote during my Masters of Human Nutrition research unit about vitamin C and the common cold.
There is widespread belief that vitamin C cures the common cold.(1) Scientific research about the effect of increased vitamin C intake and its effect on alleviating or preventing the symptoms of the common cold have shown mixed results.(2, 3) Therefore, the evidence behind this claim has been inconsistent and controversial.(2-4)
In the early 1970s, two-time Nobel Prize winner and renowned researcher, Linus Pauling conducted much research about the effects of vitamin C and after performing placebo-controlled trials, was convinced that megadoses of vitamin C could significantly reduce the incidence and alleviate the symptoms of the common cold.(4) He claimed that ingesting megadoses (1g/day) of ascorbic acid significantly reduced the prevalence and severity of the common cold.(4) Pauling later published his research in a book, ‘Vitamin C and the Common Cold’.(4) Despite lack of support for his research by the medical community at the time, public support continued to grow.
A meta-analysis conducted by Hemilia, Chalker and Douglas(3) as well as a systematic review performed by Heimer, Hart, Martin and Rubio-Wallace(5) consistently found that daily supplementation of vitamin C in dosages as high as 1g/day did not prevent the common cold. However, some studies found that routine daily supplementation of vitamin C in dosages greater than 200mg/day may insignificantly reduce the duration of symptoms by one to four days, but evidence is inconclusive. Research has shown that Linus Pauling’s theory that increased vitamin C intake will prevent the common cold is incorrect.(2, 3, 5)
I think this text extracted from a commonly used tertiary nutrition science textbook sums it up nicely:
“Newspaper headlines touting vitamin C as a cure for colds have appeared frequently over the years, but research supporting such claims has been conflicting and controversial. Some studies find no relationship between vitamin C and the occurrence of the common cold, whereas others report fewer colds, fewer days and shorter duration of severe symptoms. A review of the research on vitamin C in the treatment and prevention of the common cold reveals a modest benefit – a significant difference in duration of less than a day. The term significant means that statistical analysis suggests that the findings probably didn’t arise by chance, but instead from experimental treatment being tested. Is one day without a cold sufficient to warrant routine daily supplementation? Supplement users seem to think so.”(6)
Vitamin C cures the common cold: FACT or FICTION? -FICTION-
1. Whitney E, Rolfes SR, Crowe T, Cameron-Smith D, Walsh A. Understanding nutrition: Australian and New Zealand edition. 1st ed. Melbourne: Cengage Learning, 2011.
2. Chalmers TC. Effects of ascorbic acid on the common cold. Am J Med 1975;58:532-6.
3. Hemila H, Chalker E, Douglas B. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2007(3):1-85.
4. Pauling L. The significance of the evidence about ascorbic acid and the common cold. Proc Natl Acad Sci USA 1971;68(11):2678-81.
5. Heimer KA, Hart AM, Martin LG, Rubio-Wallace S. Examining the evidence for the use of vitamin C in the prophylaxis and treatment of the common cold. J Am Acad Nurse Prac 2009;21:295-300.
6. Whitney E, Rolfes SR, Crowe T, Cameron-Smith D, Walsh A. Understanding nutrition: Australian and New Zealand edition. 1st ed. Melbourne: Cengage Learning, 2011.