title: Environmental risk factors for inflammatory bowel diseases: Evidence based literature review.
abstract: OBJECTIVE
  Advances in genetics and immunology have contributed to the current understanding of the pathogenesis of inflammatory bowel diseases (IBD).
  
  
  METHODS
  The current opinion on the pathogenesis of IBD suggests that genetically susceptible individuals develop intolerance to dysregulated gut microflora (dysbiosis) and chronic inflammation develops as a result of environmental insults. Environmental exposures are innumerable with varying effects during the life course of individuals with IBD. Studying the relationship between environmental factors and IBD may provide the missing link to increasing our understanding of the etiology and increased incidence of IBD in recent years with implications for prevention, diagnosis, and treatment. Environmental factors are heterogeneous and genetic predisposition, immune dysregulation, or dysbiosis do not lead to the development of IBD in isolation.
  
  
  RESULTS
  Current challenges in the study of environmental factors and IBD are how to effectively translate promising results from experimental studies to humans in order to develop models that incorporate the complex interactions between the environment, genetics, immunology, and gut microbiota, and limited high quality interventional studies assessing the effect of modifying environmental factors on the natural history and patient outcomes in IBD.
  
  
  CONCLUSIONS
  This article critically reviews the current evidence on environmental risk factors for IBD and proposes directions for future research.
authors.affiliation: Ayokunle T Abegunde, Tauseef Ali, Section of Digestive Diseases and Nutrition, Department of Medicine, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, United States.
authors.forename: Ayokunle T
authors.initials: AT
authors.lastname: Abegunde
authors.affiliation: Ayokunle T Abegunde, Tauseef Ali, Section of Digestive Diseases and Nutrition, Department of Medicine, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, United States.
authors.forename: Bashir H
authors.initials: BH
authors.lastname: Muhammad
authors.affiliation: Ayokunle T Abegunde, Tauseef Ali, Section of Digestive Diseases and Nutrition, Department of Medicine, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, United States.
authors.forename: Owais
authors.initials: O
authors.lastname: Bhatti
authors.affiliation: Ayokunle T Abegunde, Tauseef Ali, Section of Digestive Diseases and Nutrition, Department of Medicine, Oklahoma University Health Sciences Center, Oklahoma City, OK 73104, United States.
authors.forename: Tauseef
authors.initials: T
authors.lastname: Ali
mesh_terms: D000397:Air Pollution / Q000706:statistics & numerical data; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D001062:Appendectomy / Q000706:statistics & numerical data; D001942:Breast Feeding; D003276:Contraceptives, Oral / Q000627:therapeutic use; D004041:Dietary Fats; D004043:Dietary Fiber; D064806:Dysbiosis / Q000453:epidemiology; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D019317:Evidence-Based Medicine; D005503:Food Additives; D000069196:Gastrointestinal Microbiome; D006801:Humans; D006920:Hygiene; D061148:Hygiene Hypothesis; D000067896:Industrial Development / Q000706:statistics & numerical data; D007239:Infections / Q000453:epidemiology; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D008460:Meat; D012307:Risk Factors; D012499:Sanitation / Q000706:statistics & numerical data; D012890:Sleep; D012907:Smoking / Q000453:epidemiology; D012923:Social Class; D013315:Stress, Psychological / Q000453:epidemiology; D014612:Vaccines / Q000627:therapeutic use; D014808:Vitamin D Deficiency / Q000453:epidemiology; D014876:Water Pollution / Q000706:statistics & numerical data
chemical_list: D000900:Anti-Bacterial Agents; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003276:Contraceptives, Oral; D004041:Dietary Fats; D004043:Dietary Fiber; D005503:Food Additives; D014612:Vaccines
keywords: Environmental factors; Exposomes; Inflammatory bowel disease