January 9, 2006 – Daily vitamin C intake would prevent colds, but not reduce the duration or severity of symptoms, Japanese researchers say.
These results come from a study carried out over three and a half years on 244 subjects who were asked to take either 50 mg or 500 mg of vitamin C per day. All of the participants lived in the same village in Japan.
In participants who took 500 mg of vitamin C per day, colds were less common than in those who consumed 50 mg per day. The researchers specify, however, that once they caught a cold, all the subjects were similarly inconvenienced. Vitamin C would therefore have no impact on cold symptoms or their duration.
This study adds to the massive scientific literature that already exists on the subject, and to the controversy surrounding the effectiveness of vitamin C in preventing and treating colds. According to recent studies, including a meta-analysis, vitamin C supplements offer no protection against the common cold, but reduce its duration and reduce its symptoms very slightly. This contradicts the results obtained by Japanese researchers.
It should be noted that this new study has weaknesses, including the lack of a control group and a clear definition of what constitutes a cold. The authors themselves point out that the results should be interpreted with caution.
Jean-Benoit Legault – PasseportSanté.net
Sasazuki S, Sasaki S, Tsubono Y et al. Effect of vitamin C on common cold: randomized controlled trial, Eur J Clin Nutr. 2005 Aug 24.
