Final answer:
Common diseases of the digestive system include food allergies, ulcers, and heartburn, with symptoms ranging from abdominal discomfort to more severe ailments.
Step-by-step explanation:
Diseases of the digestive system are highly prevalent in the United States and can range from mild discomfort to severe conditions. Some of the most common digestive diseases include food allergies, ulcers, and heartburn. Others like foodborne illnesses and food intolerance are also significant. Gastrointestinal illnesses can be classified based on whether they are caused by infectious pathogens or by toxins, and symptoms often include abdominal discomfort, nausea, diarrhea, and vomiting. The severity of these illnesses can range widely, with some being easily treatable while others may require hospitalization and can, in severe cases, be life-threatening.