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Sun Exposure Might Impact Inflammatory Bowel Disease

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Inflammatory Bowel Disease related image Photo: Getty Images

Don’t discount the power of the sun when it comes to the prevention of inflammatory bowel disease, namely Crohn’s disease and ulcerative colitis.

American researchers -- curious about European studies linking lack of sun exposure and inflammatory bowel disease -- looked at data from the massive Nurses’ Health Study, which began collecting various types of information in the 1970s.

Here’s what a new analysis of the data found: People who lived in sunnier areas of the United States were less likely to have developed an IBD.

Specifically, participants from the Nurses’ Health Study who lived in the southern states versus the northern states were 52 percent less likely to develop Crohn’s disease by the age of 30, and 38 percent less likely to develop ulcerative colitis.

Crohn’s disease and ulcerative colitis are the two main inflammatory bowel diseases, both chronic in nature and both causing flare-ups of abdominal pain and cramping, bouts of diarrhea, fatigue and anemia.

IBD is hard to diagnose, but once diagnosed, it often spells intestinal surgery to bring it under control. With estimates that Crohn’s disease and ulcerative colitis affect 1.4 million Americans, the medical community is anxious to get a handle on prevention and treatment.

The new information on the possible benefits of sun exposure in regard to IBD came from Massachusetts General Hospital in Boston, which published its study January 11, 2012 online in Gut: An International Journal of Gastroenterology and Hepatology.

The data came from the Nurses’ Health Study I, launched in 1976, and the Nurses’ Health Study II, which began in 1989. Researchers followed where the 238,000 participants lived and whether they had ever been diagnosed with an IBD.

"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 in a Gut news release.

The study authors added that Vitamin D from sun exposure theoretically plays a role in providing immunity to and regulating inflammatory response.

Further research might look into environmental pollution or infections as other possible explanations for regional differences in the incidence of IBD.

On a related note, the Crohn’s and Colitis Foundation of America says that Vitamin D deficiency is common among Crohn’s patients and recommends looking into a Vitamin D supplement if your disease is active and if you live in a non-sunny area of the country. Check with your doctor first, however.


“Geographical variation and incidence of inflammatory bowel disease among US women” (abstract). Gut. Web. 23 Jan. 2012. http://gut.bmj.com/content/early/2012/01/03/gutjnl-2011-301574.abstract

Preidt, Robert. “Inflammatory Bowel Disease Less Common in Sunny States.” HealthDay. Web. 23 Jan. 2012. http://www.nlm.nih.gov/medlineplus/news/fullstory_120737.html

Goodman, Brenda. “Climate Tied to Inflammatory Bowel Disease Risk.” WebMD. 23 Jan. 2012.

“About Crohn’s Disease.” Crohn’s & Colitis Foundation of America. Web. 23 Jan. 2012.

“About Ulcerative Colitis & Proctitis.” Crohn’s & Colitis Foundation of America. Web. 23 Jan. 2012.

“Diet and Nutrition.” Crohn’s & Colitis Foundation of America. Web. 23 Jan. 2012.

Reviewed January 24, 2012
by Michele Blacksberg RN
Edited by Jody Smith

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We value and respect our HERWriters' experiences, but everyone is different. Many of our writers are speaking from personal experience, and what's worked for them may not work for you. Their articles are not a substitute for medical advice, although we hope you can gain knowledge from their insight.

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