FRIDAY, Jan. 6 (HealthDay News) -- Inflammatory bowel disease (IBD) is becoming more common around the world, according to a new study.

Researchers who analyzed data from all population-based studies about the incidence and/or prevalence of IBD found that the rate of new cases is increasing or stable in virtually every region of the world that has been studied. Canada and Europe had the highest number of cases, while Asia had a lower prevalence, the investigators found.

IBD has been rare in developing nations, but incidence of the disease has increased as these countries become more industrialized, according to study lead author Dr. Gilaad Kaplan, of the University of Calgary, and colleagues.

IBD includes Crohn's disease and ulcerative colitis. Crohn's involves inflammation and ulceration in the deep layers of the intestinal wall. Symptoms include abdominal pain, diarrhea, weight loss and occasional bleeding. Ulcerative colitis occurs in the inner lining of the colon or rectum. Symptoms include abdominal cramps, diarrhea and rectal bleeding.

The researchers found that incidence rates for both Crohn's and ulcerative colitis were highest among people aged 20 to 40. This means that these diseases affect people in what are typically the most healthy and productive years of life, resulting in long-term cost to the patients, health care systems and society, the study authors noted.

The study is published in the January issue of the journal Gastroenterology.

"Insight into the worldwide epidemiology of inflammatory bowel disease is important for the identification of geographic patterns and time trends," Kaplan said in a news release from the American Gastroenterological Association.

"Our findings will help researchers estimate the global public health burden of inflammatory bowel disease so that appropriate health care resources are allocated, and targeted research is conducted in specific geographic regions," he added.

More information

The Crohn's and Colitis Foundation of America has more about IBD.