is it true that Vitamin Zinc is responsible in preventing flu and not Vitamin C?

My brother-in-law swears by zinc for preventing colds. It also good to break open and apply to a cold sore. I take vitamin C every day. I did take Zinc for awhile but it must be taken with food. It took me awhile to figure out what was making me nauseaus. I do everything I can to prevent colds because I have fibromyalgia so when I get a cold, my whole body aches so bad I can't walk. I'm sick enough without getting colds. I use echinacea - echinacea tea is the best at the first sign of a cold. Cold FX is the newest rage that works as well. We all need all sorts of vitamins. It is best for everyone to take a multi-vitamin. Adding Vitamin C is a bonus but your body will reject what it doesn't need if you take too much. If you really want to prevent the flu, wash your hands a lot and drink plenty of water.