Updated Cochrane Review weighs in on its benefits
Vitamin C for treating the common cold has been in debate since the early seventies, but does it really work? The Cochrane Review set out to find if vitamin C reduces the occurrence of colds, duration or severity of cold when used either as a continuous regular supplementation every day or as a therapy at the onset of cold symptoms, according to the reviews abstract.
Researchers examined trials that were mostly randomized, double-blind trials that were extracted from various sources including MEDLINE (1966 to November week 3, 2012) and even the U.S. National Institutes of Health trials register and WHO ICTRP on 29 November 2012.
Among the trials examined; five trials involved a total of 598 marathon runners, skiers and soldiers on subarctic exercises, 31 comparisons examined effect of regular vitamin C on common cold duration in adults and children.
The findings revealed regular doses of vitamin C at one gram a day or higher reduced the duration of colds on average for adults by eight percent and in children by 18%. In five trials with 598 participants exposed to short periods of extreme physical stress (including marathon runners and skiers) vitamin C halved the common cold risk However, on average adults only have a few common colds and children around six, therefore, taking vitamin C supplements everyday does not appear to be feasible.
Trials of high doses of vitamin C administered therapeutically, starting after the onset of symptoms, showed no consistent effect on the duration or severity of common cold symptoms. Only a few therapeutic trials were conducted and none of the trials involved children. One large trial with adults reported benefit from an 8 g therapeutic dose at the onset of symptoms, and two therapeutic trials using five-day supplementation reported benefit.
The authors write in their conclusion “Nevertheless, given the consistent effect of vitamin C on the duration and severity of colds in the regular supplementation studies, and the low cost and safety, it may be worthwhile for common cold patients to test on an individual basis whether therapeutic vitamin C is beneficial for them. More trials are necessary to settle the possible role of therapeutic vitamin C, meaning administration immediately after the onset of symptoms.”
The benefits of vitamin C can be found online at WebMD.