title: Geographical variability and environmental risk factors in inflammatory bowel disease.
abstract: The changing epidemiology of inflammatory bowel disease (IBD) across time and geography suggests that environmental factors play a major role in modifying disease expression. Disease emergence in developing nations suggests that epidemiological evolution is related to westernisation of lifestyle and industrialisation. The strongest environmental associations identified are cigarette smoking and appendectomy, although neither alone explains the variation in incidence of IBD worldwide. Urbanisation of societies, associated with changes in diet, antibiotic use, hygiene status, microbial exposures and pollution have been implicated as potential environmental risk factors for IBD. Changes in socioeconomic status might occur differently in different geographical areas and populations and, consequently, it is important to consider the heterogeneity of risk factors applicable to the individual patient. Environmental risk factors of individual, familial, community-based, country-based and regionally based origin may all contribute to the pathogenesis of IBD. The geographical variation of IBD provides clues for researchers to investigate possible environmental aetiological factors. The present review aims to provide an update of the literature exploring geographical variability in IBD and to explore the environmental risk factors that may account for this variability.
authors: Department of Medicine and Therapeutics, Institute of Digestive Disease, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, NT, Hong Kong, Hong Kong. siewchienng@cuhk.edu.hk
authors: Siew C
authors: SC
authors: Ng
authors: Charles N
authors: CN
authors: Bernstein
authors: Morten H
authors: MH
authors: Vatn
authors: Peter Laszlo
authors: PL
authors: Lakatos
authors: Edward V
authors: EV
authors: Loftus
authors: Curt
authors: C
authors: Tysk
authors: Colm
authors: C
authors: O'Morain
authors: Bjorn
authors: B
authors: Moum
authors: Jean-Frédéric
authors: JF
authors: Colombel
mesh_terms: D004781:Environmental Exposure / Q000009:adverse effects*; D005843:Geography; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000209:etiology*; D012307:Risk Factors