What is the best food to eat when you are sick?

Thanks for your question !

The following food I would have taken if I feel sick

The BRAT diet: Bananas, Rice, Apple sauce and Toast. Also oatmeal, boiled potatoes, saltine crackers, and baked chicken or turkey without skin is safe bets. 

And I would have avoided Sugarless candy and gum containing sorbitol or other artificial sweeteners, which aren't digestible and can trigger diarrhea. Other foods that can cause gas and bloating include onions, apples, broccoli, cabbages, and beans. Dairy may also aggravate diarrhea, as well as alcohol and caffeine.

Again , the types of food will be vary based on the sign and symptoms of the disease but above mentioned food I normally take.