Another suspect for Crohn's disease is a tuberculosis-like organism. Because inflammatory bowel disease is much more prevalent in industrialized nations, experts believe environmental factors, such as diet, must play some role, although studies have been conflicting. A high intake of fluids and diets rich in fruits, vitamin C, and magnesium were associated with a lower risk for both disorders, and a high intake of potassium and vegetables was associated with a lower risk for Crohn's only. Ulcerative colitis and Crohn's disease share many symptoms, although they also differ in important ways. Both are chronic diseases and symptoms usually appear in young adults.
Symptoms can be mild or very severe and disabling.
They can develop gradually or have a sudden onset. The severity of symptoms and relapse rates also vary with seasons, with highest risk in the winter and autumn and lowest in summer. Crohn's disease is diarrhea. Blood may appear in the stools, especially with ulcerative colitis. The blood may be readily visible or visible only using a microscope, in which case it is called occult blood.