Obviously high doses of vitamin C are a good idea for a cold. I have heard arguments all my life for and against taking supplements. Some say they are essential with our generally "junk" food diets, and others say that that they run right through a person and do little.
When you see these people starving in these third world countries you have to wonder. They come down with nutritional diseases and lose their eyesight (when a single megadose of vitamin E can prevent that). So i suspect that there is some use for them.