According to the research done by the Australian National University and the University of Helsinki in Finland, vitamin C will not ward off common cold or shorten its length or severity for an average persons. Only individuals under extreme physical stress, such as athletes and soldiers, will benefit from Vitamin C by reducing their risk of catching a cold.
These findings are based on a review of 30 published studies involving 11,350 people who took at least 200 milligrams of vitamin C each day. The details of the study appears in the latest issue of the Cochrane Library, published by the Cochrane Collaboration, an organization that evaluates medical research.
Generally, the protection offered by the vitamin C supplements is so slight it is not worth the effort or expense, the researchers say.
Actually, I am not surprised about this. My family doctor has told me multiple times that vitamin C is useless against cold. However, when I have a cold, I still want to do something to eliminate it. Taking vitamin C pills may not work, but at least I am doing something. It just makes me feel better. I guess vitamin C has a psychological effect on cold:
taking vitamin C pill -> thinking vitamin C will get rid of the cold -> mentally happier -> body recovers faster -> body's immune system fights off cold virus -> cold gone -> body is healthy again