The idea that vitamin C can stop from you from catching a cold and can alleviate the symptoms of a cold, first came about because a very famous scientist, Linus Pauling (1901-1994) who is the only person ever to win two Nobel prizes (Chemistry in 1954 and Peace in 1962) proposed it. He published a book, in 1970, called, ‘Vitamin C and the Common Cold‘ and in it, he claimed that taking 1,000 mg/d of vitamin C would reduce the chance of catching a cold by a massive 45%. The recommended amount of vitamin C for adults in the UK at the time, was and still is, 25 X less; 40 mg/day.
Not long after (in 1975), an influential study was published by the National Institute of Health (NIH). Researchers compared vitamin C pills with a placebo pill, in a double blind study, with half the subjects taking vitamin C and half a placebo, for 9 months. When the results were analysed, the vitamin C group reported having fewer colds. This study vindicated Pauling’s views and the idea that vitamin C could stop you catching a cold became embedded in the popular imagination.
However, not everyone agreed. Dr. Terence Anderson, in Canada, conducted numerous, large clinical trials throughout the 1970’s, involving thousands of volunteers, comparing vitamin C with a placebo. He found that there was no benefit of taking vitamin C supplements to prevent a cold, although vitamin C could slightly reduce the severity of cold symptoms, but that the very high doses suggested by Pauling were not needed.
It then emerged that the NIH study had a big problem. Although the study was supposed to be double-blind, almost half the subjects had been able to guess which pill they were getting. The results were re-analysed and the researchers found that among the subjects who hadn’t guessed which pill they had been taking, there was no difference at all in the number of colds between those who got the vitamin C and those who got the placebo. This finding demonstrated the power of the placebo; when people believe that they are doing something effective (like a taking a supplement or retrieving an alternative treatment) it can have a real effect. The strength of the so-called ‘placebo effect‘ is well documented and has been borne out in many studies. In fact, a red placebo pill is much more powerful than a white one!
The Common Cold Unit was set up by David Tyrell, in 1946, in Wiltshire, with the aim of finding a cure for the cold. Thirty (paid) volunteers were recruited every fortnight and were exposed to cold viruses. All sorts of preventive compounds, including vitamin C, were tested in the hope they could prevent or alleviate the common cold. The unit was closed in 1989 after failing to find a cure; nothing worked.
More recently, all of the scientific evidence (16 large, well designed, double blind studies) was reviewed and the conclusion was this: vitamin C supplementation does not reduce your chance of catching a cold and routine vitamin C supplementation is a waste of time. They also found, like Anderson, that there was a slight reduction in symptoms reported in some of the studies but it was very small and not really of clinical significance. Vitamin C was found to be useful in preventing colds for people exposed to brief periods of severe physical exertion (like high performance athletes and solders in extreme climates) but not in the general population.
So, the take home message is this: for most people, taking vitamin C supplements will not stop you catching a cold and if you do happen to catch a cold, vitamin C may have a very small, beneficial, effect on your symptoms. However, the placebo effect might make you feel better.
One last thought; chicken soup is the way to go. As early as 60AD a Roman surgeon under Nero, Pedacius Dioscorides, suggested it as a cold cure and it was hailed as “an excellent food, as well as medication” by the 12th Century physician Moses Maimonides. Scientific studies have demonstrated that chicken contains the amino acid cysteine, which has mild decongestant proprieties. Enjoy!