The exposome-diet-epigenome axis in inflammatory bowel diseases—a narrative review

Background and Objective: Inflammatory bowel disease (IBD) is an immune-mediated disease of the gastrointestinal (GI) tract. Its pathophysiology is influenced by environmental and epigenetic factors such as diet, microbiota, genetics, and DNA modifications. Omics analysis has provided valuable insights into the role of these factors in IBD pathogenesis and the identification of potential biomarkers. Methods: To interpret the evidence on the association of environmental factors, such as diet, with IBD onset and their impact on the genome, a literature review using the MEDLINE database within the National Library of Medicine (PubMed) was performed. Key Content and Findings: IBD is a multifactorial disease involving genetic and epigenetic factors, and understanding its etiology has been challenging to many researchers. Different elements of the exposome may induce epigenetic changes related to IBD. One of the most scrutinized in the last few years is diet and how it can modulate the microbiome. Conclusions: Genomics does not explain the disease in its entire pathophysiology, and this opened the possibility of investigating other pathways and factors, such as the epigenome, microbiome, diet, and exposome, to better understand IBD. We emphasized in this review the relevance of researching IBD more broadly, mainly looking at association studies, although mechanistic ones still need to be improved in the literature. This review highlights the need for a comprehensive investigation of the Exposome-Diet-Epigenome axis to enhance our understanding of IBD and its outcomes.