Related Experiment Video
Updated: Nov 19, 2025

Cigarette Smoke Exposure in Mice using a Whole-Body Inhalation System
Published on: October 22, 2020
Exploring the Effects of Cigarette Smoking on Inflammatory Bowel Disease Using Mendelian Randomization
Daniel P Jones1,2, Tom G Richardson1,3, George Davey Smith1,3,4
1Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
Background:
Previous observational evidence has suggested an association between smoking and inflammatory bowel disease (IBD).
Methods:
We used observational techniques followed by Mendelian randomization to explore whether smoking is a causal factor in the development of IBD and its subtypes.
Results:
In those who have ever smoked, we observed increased risk of IBD and, in current smokers, we observed increased risk of Crohn disease and decreased risk of ulcerative colitis. However, our Mendelian randomization analyses found little evidence that smoking affects the development of IBD.
Conclusion:
Overall, our results suggest that smoking does not causally influence the risk of IBD.
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