Sunlight, Vitamin D, and Crohn's Disease

Crohns risk connected to location and essential vitamins

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Why do some people develop Crohn's disease, and others don't? Scientists are working to find out what puts people at higher risk for developing this gastrointestinal condition.

A number of health conditions are believed to be correlated with latitude, or distance from the equator. Previous studies had found that the risk of developing Crohn's is higher in northern latitudes than southern latitudes in European countries, but this had not yet been established in United States – until now.

"Ask your doctor about your risk for Crohn's."

Two teams of researchers presented new findings on risk factors at the American College of Gastroenterology's recent scientific meeting. The first group found that the risk of developing Crohn's and ulcerative colitis is lower in the southern United States than it is in the north.

The second group found that high doses of vitamin D3 may improve treatment of Crohn's, which affects as many as 1.4 million patients, nationwide.

The first study, conducted by scientists at Massachusetts General Hospital, used data from the Nurses Health Study I and II. The Nurses Study I was started in 1976, with information collected from nurses living in the 11 most populous states at that time. Nurses Study II started in 1989, looking at a younger population. Every two years, the nurses fill out questionnaires with their current health information.

Among the nurses who participated in both of these studies, they found 284 cases of Crohn's disease, a chronic inflammatory disease of the intestines, and 332 cases of ulcerative colitis, an inflammatory bowel disease that affects the colon.

The researchers found that although women were diagnosed around age 50, where they were living when they were 30 was strongly associated with incidence of disease. That means that if they were living in northern latitude locations such as Chicago at age 30, they were more likely to develop the disease than women living in southern latitude areas, like Texas. Women who were living in southern latitudes were 50% less likely to develop Crohn's, and 35% less likely to develop ulcerative colitis.

Dr. Hamed Khalili, a study author, explained that the different risk factors could have to do with exposure to UV light, pollution, or vitamin D.

People get most of their natural vitamin D from sunlight, which is converted into this nutrient by our skin. That could potentially explain why people located further from the equator – and that get less sun exposure throughout the year – have greater risk of a Crohn's diagnosis.

Crohn's patients frequently have low levels of vitamin D, as do many Americans. A small trial study conducted at Weill-Cornell Medical tested if high doses of vitamin D3, a form of vitamin D, would improve clinical outcomes in patients.

Indeed, the first 15 patients given the high-dose of the vitamin had changes in disease activity, whereas those who took a low dose had no change. This is preliminary data, and more research needs to be done.

Reviewed by: 
Review Date: 
October 30, 2011
Last Updated:
November 17, 2011