There is no evidence that Vitamin C prevents colds - the one exception is people who have done a marathon or other extreme exertion.
This despite a lot of research.
May be an effect on the duration of colds but evidence is not clear.
www.cochrane.org/CD000530/ARI_echinacea-for-preventing-and-treating-the-common-cold
There is very little evidence that echinacea prevents colds. It may, slightly, shorten them but it is a weak effect.
www.cochrane.org/CD000530/ARI_echinacea-for-preventing-and-treating-the-common-cold
These conclusions were reached after careful examination of the most well-conducted studies.
Washing hands is the single best prevention - and keeping hands away from face. In one study middle aged women who went on a walk in the fresh air every day got fewer colds.
Shingles and pneumococcal vaccines side effects




