Geographic variation does play a role in determining occurrence of chronic digestive diseases, US researchers say.
The new research points to a potential role for UV light exposure and vitamin D levels in chronic digestive conditions, Crohn’s disease, which is a serious inflammatory condition in the small intestine and ulcerative colitis (UC), which similarly affects the colon.
In two separate studies a group of investigators from Massachusetts General Hospital probed the connection between geography, UV exposure and incidence of inflammatory bowel disease while another group from Weill Cornell Medical Center looked at different levels of supplementation with Vitamin D to determine impact on severity of Crohn’s disease.
Results from two large prospective studies revealed a significant north south gradient in the association between latitude and incidence of Crohn’s disease and ulcerative colitis in the United States.
“This differential risk may be explained by differences in UV light exposure, vitamin D status, or pollution,” explained Dr. Hamed Khalili, who, along Dr. Andrew Chan and colleagues at Massachusetts General Hospital, analyzed data that included a 4,209,454 person-year follow up in which they confirmed 284 cases of Crohn’s disease and 332 cases of ulcerative colitis.
While the mean age of diagnosis among the women was 51 for Crohn’s and 48 for UC, the investigators found that the women’s geographic location at age 30 was strongly associated with incidence of disease.
Based on geographic location at age 30, compared to women in northern latitudes, women in southern latitudes had an adjusted hazard ratio of 0.51 for Crohn’s and 0.65 for UC suggesting that the risk of disease is 50 percent and 35 percent lower in the southern latitudes compared to northern latitudes for CD and UC, respectively.
Results of an interim analysis of the first 15 patients in the study conducted at Weill-Cornell Medical revealed that ‘High-dose Vitamin D3 Improves Clinical Activity in Crohn’s Disease’.
Both the studies were presented at American College of Gastroenterology’s 76th Annual Scientific Meeting and ACG Annual Scientific Meeting by Dustin Boothe respectively.