Papaya is one of the most popular fruits for curing upset stomach and diarrhea. Eating papaya eases indigestion and helps with constipation. The magic is in the papain enzymes, a natural digestive enzyme that breaks up foods irritating the stomach and chymopapain, which helps to breakdown proteins and soothe the stomach by promoting a healthy acidic environment. Papayas are a great snack at anytime of the day.