Inflammatory Bowel Disease Less Common in Sunny States

Researchers say sunshine may boost vitamin D levels, affecting immune function

By Robert Preidt 

 

 

 

  People who live in sunnier regions of the United States are less likely to develop inflammatory bowel disease, a new study says. The findings support previous European research and could lead to new types of treatment and preventive measures, the study authors said.
Inflammatory bowel disease (IBD) includes Crohn's disease and ulcerative colitis, which can be extremely painful and require surgery. The causes of IBD remain largely unknown.
In this study, researchers analyzed long-term data collected from 238,000 participants in the Nurses' Health Study I and the Nurses' Health Study II, which were launched in 1976 and 1989, respectively. None of the participants had inflammatory bowel disease at the start of the studies.
Compared to participants who lived in northern areas of the United States, those living in southern areas were 52 percent less likely to develop Crohn's disease by the age of 30 and 38 percent less likely to develop ulcerative colitis.
The study appears online in the journal Gut.
"A leading explanation for this north-south gradient in the risk of ulcerative colitis and Crohn's disease may be differences in exposure to sunlight, or UVB radiation, which is generally greater in southern latitudes," wrote Dr. Hamed Khalili, of Massachusetts General Hospital in Boston, and colleagues.
"UV radiation is the greatest environmental determinant of plasma vitamin D, and there is substantial experimental data supporting a role for vitamin D in the innate immunity and regulation of inflammatory response," they noted.

As Nations Develop, So May Bowel Disease

 

Researchers identify inflammatory bowel disease as a global problem

By Robert Preidt 

 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.
SOURCE: American Gastroenterological Association, news release, Jan. 4, 2012