Flu season is not the time to skimp on your daily dose of vegetables, healthy fats, and whole grains. A balance of the vitamins, minerals, and electrolytes you need from a well-balanced diet helps keep your immune system in top shape, Furuya says.
Research shows extra vitamin C may help lower the risk of catching a cold for people who expose their bodies to extreme stress—think distance running or long hours on the ski slopes, while other studies suggest extra C may lessen the severity of symptoms if you do catch a cold. Bottom line: It can't hurt. Load up on cantaloupe, citrus fruits, mango, pineapple, green and red pepper, spinach, and tomato—or pop a 500mg supplement daily.