Gastrointestinal (GI) diseases refer to a wide range of conditions affecting the digestive system. The digestive system is a complex network of organs and these diseases can lead to various symptoms and problems.

Symptoms
The most common symptoms are nausea, vomiting, diarrhea, constipation, bloating or abdominal pain.

Treatment
The treatment depends on the specific condition, its severity, and symptoms. It could vary from lifestyle modification, diet changes, and supplement intake to more serious once such as antibiotics.