P862 Dietary risk factors associated with onset of IBD: a systematic literature review and meta-analysis

Abstract Background Several potential risk factors for Inflammatory Bowel Disease (IBD) have been highlighted, including dietary factors. Previous evidence has highlighted associations between high fibre, fruit, and vegetable intake and decreased risk of IBD. Conversely, low intake of dietary fibre, and low vitamin D levels are associated with incident IBD. One systematic review reported that high intake of total fats, PUFAs, and omega-6 fatty acids, were associated with an increased risk of Crohn’s Disease (CD) and Ulcerative Colitis (UC), whereas high fibre and fruit intakes were associated with decreased CD risk, and high vegetable intake was associated with decreased UC risk. Despite this evidence, there remains a paucity of literature reporting on the various dietary risk factors for IBD systematically and quantitatively. Thus, the purpose of this systematic review is to determine whether dietary factors are associated with risk of developing IBD Methods We conducted searches in the following electronic databases: Ovid MEDLINE, Web of Science, and the Cochrane Library. Keywords and search terms related to ‘diet’ and ‘inflammatory bowel disease’ were applied. This review includes case-control, cohort studies, and RCTs investigating the association between dietary factors and onset of IBD. Study protocol details have been published on the International prospective register of systematic reviews (PROSPERO). Available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022290798Databases Results Our search identified 14,809 relevant articles to include, outlined in Figure 1. After title and abstract screening there were 119 articles that met the eligibility criteria. Overall, 24 articles were deemed suitable for study synthesis. When compared with those consuming the highest intake of carbohydrates, those consuming the lowest levels of carbohydrates had an overall reduced risk of IBD of 30% (RR 0.70, 95% CI 0.51-0.89) and a reduced risk of CD of 37% (RR 0.63, 95% CI 0.32-0.94). When compared with those consuming the lowest intake of vegetables, those consuming the highest levels of vegetables had an overall reduced risk of IBD of 42% (RR 0.58, 95% CI 0.53-0.63). When stratified by sub-group, those consuming the highest intake of vegetables compared with the lowest had a reduced risk of 87% of IBD (RR 0.13, 95% CI 0.04-0.22), 52% of UC (RR 0.48, 95% CI 0.24-0.71) and a reduced risk of CD of 18% (RR 0.82, 95% CI 0.76-0.88). Conclusion This systematic review provides a detailed summary of dietary factors associated with the onset of IBD. This evidence will inform on potential preventative strategies for IBD and will inform the academic community, patients, and policy makers about the role of dietary factors in the development of IBD.