Pay attention to the signs and see your health care practitioner if they persist. Signs of an Unhealthy Gastrointestinal System: Gas, bloating, heartburn/acid reflux, diarrhea, constipation, irritable bowel syndrome. Learn more about the steps to getting a healthy gastrointestinal system that reduces cancer risk by clicking on the image above. Please pin to save for later. Together we can educate the world about healthy lifestyle!