Posted on 06/14/2012 at 02:45:28 PM by Suzanne PriceBy Stefano Vendrame
Together with Echinacea and zinc lozenges, high-dose vitamin C is one of the most popular remedies for treating the first symptoms of a cold, following the traditional advice given by Nobel laureate Dr. Linus Pauling in his famous book Vitamin C and The Common Cold back in 1970 (1). However, the mainstream idea among nutrition professionals today is that Dr. Pauling's theories on vitamin C were wrong and largely disproven by subsequent scientific studies. I am admittedly biased, not so much because I spent part of my training at the Linus Pauling Institute at Oregon State University, but due to persuasive personal experience. I always follow Dr. Pauling's advice at the first symptoms of a cold and pop 1 g of vitamin C every hour for 10 hours, and so far it has never failed me. Am I really, after seven years doing scientific research, being fooled every time by an insipid placebo effect?
To find out, I decided to do what a PhD student is supposed to do, which is running a search for peer-reviewed scientific papers. What I found, to my utmost surprise, is that Dr. Pauling's advice has never been tested. Granted, dozens of human trials investigating vitamin C for the prevention or treatment of the common cold have been performed over the last forty years, the most recent of which was just published and showed that a combination of 1 g of vitamin C and 10 mg of zinc was able to reduce cold symptoms and duration compared to a placebo, with no side effects (2).
However, out of all these studies, many tested ridiculously low dosages (lower than 200 mg/day) and, predictably, found hardly any effect. A 2007 Cochrane review of the 30 trials using daily doses of at least 200 mg concluded that vitamin C more than halved the incidence of colds in people exposed to acute physical stress, while in the general population the reduction was only 8%. Nevertheless, concluded the authors, “it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them” (3). Moreover, the few prophylaxis trials testing higher doses of vitamin C (1 g per day or more) consistently found greater reductions in the incidence of colds (4). With regard to studies testing vitamin C supplementation after the first symptoms of cold have appeared, most studies supplementing at least 2 g of vitamin C found statistically significant reductions in either the duration or the symptoms of colds, and the outcome is generally dose-dependent (better results with higher doses), although the doses tested in these studies are far from the 10 daily grams recommended by Dr. Pauling (5).
The available evidence suggests that vitamin C is indeed helpful for the common cold, but a trial following Pauling's recommended doses remains to be carried out. This scientist won two Nobel prizes, could we at least give him a shot and test his theories, following his instructions? I think that would be common sense before arguing pro or against his conclusions. And in the meantime, for extra measure, I'll go get some vitamin C.
(1) Pauling L. Vitamin C and the Common Cold. W. H. Freeman, 1970.
(2) Maggini S et al., A combination of high-dose vitamin C plus zinc for the common cold. J Int Med Res, 2012, 40:28-42.
(3) Douglas RM et al., Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev, 2007, 17:CD000980.
(4) Hemilä H. The effect of vitamin C on the common cold. J Pharm Pract. 2011, 24:241-2.
(5) Hemilä H. Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit. Med Hypotheses. 1999, 52:171-178.