An Australian study has concluded that the public’s love affair with vitamin C and cold prevention is somewhat unjustified. They did find, however, that it was useful in preventing colds in people exposed to extreme physical exertion or cold temperatures.
The review and the following tests, conducted by Robert M. Douglas of the Australian National University, and Harri Hemila of the University of Helsinki, found that vitamin C had little or no effect on cold symptoms or cold duration.
All studies reviewed involved a daily dose of at least 200mg tested against a placebo. The supplemental use of vitamin C did not reduce the risk of catching a cold. However, the studies were able to find a small reduction in the duration of the cold.
The study authors concluded, “the lack of effect of prophylactic vitamin C supplementation on the incidence of common cold in normal populations throws doubt on the utility of this wide practice.”
Common threads were found in six studies, however, that point to benefits of vitamin C for protection in extreme conditions or environments. In six of the studies reviewed, a vitamin or a placebo was given to marathon runners, skiers, and soldiers under extreme physical stress or exposed to very cold temperatures.
On average, subjects experienced a 50% reduction in common cold incidence. The authors doubt the applicability of the findings to the general population as the studies all focused on the extremely fit.
One trial caught their attention. Patients who took a single very high 8g dose vitamin C at the onset of cold symptoms experienced a shorter illness than those who took the placebo.
Douglas and Hemila agree that the results of this study are “tantalising and deserve further assessment.”
