It’s best if the treatment is done without leaving the house for a few days. External factors such as cold or bad weather may prolong or even intensify the disease and slow your recovery. What to eat when you have the flu. You need to keep an effective defense against the influenza virus. Eat vitamin C-rich fresh fruits and vegetables. Vitamin C has excellent antioxidant properties and will help in your effort to recover. Good sources of vitamin C are citrus fruits, strawberries and Brussel sprouts.