Since the 1970's, when research advocated that doses of Vitamin C would help alleviate symptoms of the common cold, that doctrine has been generally accepted.
But in a recent review of past clinical research on this topic, it is suggested that the public's enthusiasm for vitamin C may be unjustified.
In an attempt to discover whether vitamin C could help in the prevention of a cold, researchers Robert M Douglas, from the Australian National University, and Harri Hemila of the University of Helsinki, reviewed 23 past studies on vitamin C and the common cold conducted over the last 65 years.
They found that vitamin C did not appear to help the general public in the prevention of colds, but the authors did find evidence that vitamin C could help prevent colds in people exposed to extreme physical exertion, such as marathon runners.
The researchers also found that those people who were given vitamin C and then caught a cold, experienced a small reduction in the duration of the cold compared with those taking a placebo.
In one of the trials, patients who took a single, very high dose of the vitamin (8 g) on the day their symptoms started experienced a shorter illness compared with people who took a placebo pill.
The authors declare the results in this single trial as "tantalizing and deserving of further assessment."
The review is published in this month's open access journal, PLoS Medicine.