A large number of environmental factors have been
implicated in the pathogenesis and development of IBD.
The epidemiological data are strong and are reproducible
only for smoking and appendectomy, whereas the importance
of other risk factors, such as breast-feeding,
contraceptive and NSAIDs use and sugar intake are
sharply divergent. Nevertheless, the mechanism for the
effects of all these studied environmental factors remains
unknown and the interplay between these exogenic factors
and genetic subtypes of IBD is under investigation.