What you eat is undoubtedly important to your health.  It sounds odd, but only in recent years have people put food nutrition and well being in the same thought process.

The Wall Street Journal has a good article talking about research on food and the flu.

http://online.wsj.com/article/SB10001424052748703819904574553812951678006.html

A big take away here is for the vitamins and minerals mentioned, be sure to get them from as many unprocessed whole foods as possible instead from a supplement.