Environmental risk factors of inflammatory bowel disease: toward a strategy of preventative health Original paper

What was studied?

This review focuses on the environmental risk factors associated with the development of inflammatory bowel disease (IBD), specifically Crohn’s disease (CD) and ulcerative colitis (UC). It explores the complex interplay between environmental exposures, microbiome alterations, and immune responses that contribute to the onset and progression of IBD. The review synthesizes findings from various meta-analyses, highlighting modifiable risk factors such as smoking, diet, and early-life antibiotic use, while also discussing protective factors like breastfeeding and Mediterranean diets. It aims to provide a strategy for reducing IBD risk through environmental modifications and guides healthcare providers on preventing IBD through lifestyle changes.

Who was studied?

This review does not focus on a specific patient group but instead synthesizes data from multiple studies involving a wide range of populations across different age groups and ethnic backgrounds. It includes studies from both high-prevalence and newly industrialized regions, focusing on individuals who have been exposed to various environmental factors and assessing how these exposures influence the likelihood of developing CD and UC. The review also examines preclinical cohorts, including those at high genetic risk for IBD, to identify potential biomarkers and environmental factors that may trigger disease onset.

Most important findings

The review identifies several environmental factors that contribute to the pathogenesis of IBD. Smoking is a significant risk factor, especially for Crohn’s disease, and has been shown to worsen disease progression. In contrast, a Mediterranean diet rich in fiber, fruits, vegetables, and fish has a protective effect, potentially reducing inflammation and modulating the gut microbiome. Early life exposures, such as antibiotic use and breastfeeding, play crucial roles in shaping the gut microbiota, with breastfeeding being protective against IBD. The review highlights the Hygiene Hypothesis, which suggests that a lack of early exposure to microbes in sterile environments increases the risk of immune-mediated diseases like IBD. Lifestyle factors such as physical activity, stress management, and maintaining a healthy weight are associated with a lower risk of IBD.

Key implications

The findings suggest that modifiable environmental factors present an opportunity for preventive health strategies aimed at reducing the incidence of IBD. Healthcare providers can play a pivotal role in advising patients on lifestyle and dietary changes that can mitigate the risk of developing IBD. The review also stresses the importance of future research to develop high-quality interventional studies that can more definitively assess the effectiveness of environmental modifications in preventing IBD. Identifying biomarkers associated with ecological exposures will further help in targeting high-risk individuals for early interventions. In particular, the review calls for more comprehensive studies involving diverse populations to understand the varying effects of environmental factors on IBD risk across different regions and demographics.