Identification of Environmental Factors Associated with Inflammatory Bowel Disease in a Southwestern Highland Region of China: A Nested Case-Control Study.

Junkun Niu,Yan Liu,Qi Huang,Kunhua Wang,Xiangqian Dong,Jiarong Miao,Shuxian Xia,Yuan Tang,Qiong Nan,Yinglei Miao,Gang Yang,John Green

doi:10.1371/journal.pone.0153524

Junkun Niu, Yan Liu + Show 10 more

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https://doi.org/10.1371/journal.pone.0153524

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Abstract

BackgroundThe aim of this study was to examine environmental factors associated with inflammatory bowel disease (IBD) in Yunnan Province, a southwestern highland region of China.MethodsIn this nested case-control study, newly diagnosed ulcerative colitis (UC) cases in 2 cities in Yunnan Province and Crohn’s disease (CD) cases in 16 cities in Yunnan Province were recruited between 2008 and 2013. Controls were matched by geography, sex and age at a ratio of 1:4. Data were collected using the designed questionnaire. Conditional logistic regression models were used to estimate adjusted odds ratios (ORs).ResultsA total of 678 UC and 102 CD cases were recruited. For UC, various factors were associated with an increased risk of developing UC: dietary habits, including frequent irregular meal times; consumption of fried foods, salty foods and frozen dinners; childhood factors, including intestinal infectious diseases and frequent use of antibiotics; and other factors, such as mental labor, high work stress, use of non-aspirin non-steroidal anti-inflammatory drugs and allergies (OR > 1, p < 0.05). Other factors showed a protective effect: such as consumption of fruits, current smoking, physical activity, and drinking tea (OR < 1, p < 0.05). For CD, appendectomy and irregular meal times increased the disease risk (OR >1, p < 0.05), whereas physical activity may have reduced this risk (OR < 1, p < 0.05).ConclusionsThis study is the first nested case-control study to analyze the association between environmental factors and IBD onset in a southwestern highland region of China. Certain dietary habits, lifestyles, allergies and childhood factors may play important roles in IBD, particularly UC.

Highlights

Inflammatory bowel disease (IBD) includes ulcerative colitis (UC) and Crohn’s disease (CD), and its etiology and pathogenesis remain unclear
For UC, various factors were associated with an increased risk of developing UC: dietary habits, including frequent irregular meal times; consumption of fried foods, salty foods and frozen dinners; childhood factors, including intestinal infectious diseases and frequent use of antibiotics; and other factors, such as mental labor, high work stress, use of non-aspirin non-steroidal anti-inflammatory drugs and allergies (OR > 1, p < 0.05)
This study is the first nested case-control study to analyze the association between environmental factors and inflammatory bowel disease (IBD) onset in a southwestern highland region of China

Summary

Introduction

Inflammatory bowel disease (IBD) includes ulcerative colitis (UC) and Crohn’s disease (CD), and its etiology and pathogenesis remain unclear. Studies have shown that genetics, the external environment and the gut microbiome play important roles in the development of IBD. A two- to three-fold increase in the incidence of IBD has been noted in several countries in Asia [2]. The rather quick change in IBD incidence strongly suggests that environmental factors have a clear etiological role in IBD [3]. Evidence suggests that consumption of a Western diet enriched with saturated fat, refined carbohydrates, and food additives is associated with increased IBD risk [4]. The aim of this study was to examine environmental factors associated with inflammatory bowel disease (IBD) in Yunnan Province, a southwestern highland region of China

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