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World J Gastrointest Pharmacol Ther. Feb 6, 2016; 7(1): 112-125
Published online Feb 6, 2016. doi: 10.4292/wjgpt.v7.i1.112
Influence of environmental factors in the development of inflammatory bowel diseases
Evangelia Legaki, Maria Gazouli
Evangelia Legaki, Maria Gazouli, Department of Basic Medical Sciences, Laboratory of Biology, School of Medicine, University of Athens, 11527 Athens, Greece
Author contributions: Legaki E performed all the literature searching and wrote the manuscript; Gazouli M designed, wrote and edited the manuscript.
Supported by The Hellenic State Scholarships Foundation to Legaki E.
Conflict-of-interest statement: No conflict of interest to state.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Maria Gazouli, PhD, Assistant Professor, Department of Basic Medical Sciences, Laboratory of Biology, School of Medicine, University of Athens, Michalakopoulou 176, 11527 Athens, Greece. mgazouli@med.uoa.gr
Telephone: +30-210-7462231 Fax: +30-210-7462231
Received: May 28, 2015
Peer-review started: June 1, 2015
First decision: October 14, 2015
Revised: October 20, 2015
Accepted: December 3, 2015
Article in press: December 4, 2015
Published online: February 6, 2016
Processing time: 245 Days and 15 Hours
Abstract

Idiopathic inflammatory bowel diseases (IBD), Crohn’s disease (CD) and ulcerative colitis (UC), are multifactorial diseases that are manifested after disruption of a genetic predisposed individual and its intestinal microflora through an environmental stimulus. Urbanization and industrialization are associated with IBD. Epidemiological data, clinical observations and family/immigrants studies indicate the significance of environmental influence in the development of IBD. Some environmental factors have a different effect on the subtypes of IBD. Smoking and appendectomy is negatively associated with UC, but they are aggravating factors for CD. A westernized high fat diet, full of refined carbohydrates is strongly associated with the development of IBD, contrary to a high in fruit, vegetables and polyunsaturated fatty acid-3 diet that is protective against these diseases. High intake of nonsteroidal antiinflammatory drug and oral contraceptive pills as well as the inadequacy of vitamin D leads to an increased risk for IBD and a more malignant course of disease. Moreover, other factors such as air pollution, psychological factors, sleep disturbances and exercise influence the development and the course of IBD. Epigenetic mechanism like DNA methylation, histone modification and altered expression of miRNAS could explain the connection between genes and environmental factors in triggering the development of IBD.

Keywords: Crohn’s disease; Ulcerative colitis; Epigenetics; Environment

Core tip: Epidemiological data, clinical observations and family/ immigrants studies indicate the significance of environmental influence in the development of inflammatory bowel diseases (IBD). A westernized high fat diet, full of refined carbohydrates is strongly associated with the development of IBD, contrary to a high in fruit, vegetables and polyunsaturated fatty acid-3 diet that is protective against these diseases. Additional factors such as air pollution, psychological factors, sleep disturbances and exercise influence the development and the course of IBD. Epigenetic mechanism like DNA methylation, histone modification and altered expression of miRNAS could explain the connection between genes and environmental factors in triggering the development of IBD.