Climate link to lower rates of IBD

The authors found that patients living in southerly climes were 52% less likely to develop Crohn’s disease by the age of 30 and 38% less likely to develop ulcerative colitis, compared with those residing in northern latitudes. Smoking, which is thought to affect IBD risk, had no influence on the findings. “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,” the authors commented. “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 continued. They added that their results lend credence to the importance of biological pathways in influencing geographical differences in the development of IBD.