Prevention of Inflammatory Bowel Diseases in Persons at Risk The PIONIR (Preventing IBD Onset in Individuals at Risk) Trial

Several important factors associated with CD onset have already been identified in the GEM analyses, such as elevated faecal calprotectin(FC),altered gut permeability, proteomics, anti-microbial serology, and microbiome composition. These parameters are combined into the GEM Risk Score (GRS). The first-line therapy in children with CD, according to ECCO/ESPGHAN guidelines, is exclusive enteral nutrition (EEN), meaning 8-12 weeks of exclusive liquid formula. Nutritional therapy may alter intestinal inflammation by several mechanisms, including modulation of the microbiome and an effect on intestinal permeability, both factors assessed in the GEM cohort. EEN is safe and effective, but it is challenging to implement. Several diets, based on solid foods, have been proposed as alternatives to EEN in an attempt to increase feasibility, three of which have the most data. Specific carbohydrate diet (SCD) restricts carbohydrates and processed foods and has been long used with variable reported effectiveness. The CD-TREAT diet induced a positive change to the microbiome, children with active CD entered clinical remission with decreased inflammatory markers. Crohn's Disease Exclusion Diet (CDED) is based on the exclusion of processed and pro-inflammatory foods, similar to Tasty\&Healthy. A recent RCT of CDED diet with 50% liquid formula showed comparable effectiveness as EEN, including normalization of FC and positive effect on the microbiome. However, the allowed dietary components are not liberal, and the diet is rigid, making it unsuitable as a prevention measure. In 2014, a cook-book named "Tasty\&Healthy" was published as a simple approach to dietary treatment based on the best available evidence. A steering committee of physicians experienced in IBD and nutrition, as well as leading IBD dieticians, reviewed results of dietary studies from animal models, humans and epidemiological cohorts. This review resulted in agreed-upon foods that may aggravate inflammation and thus should be excluded, including all processed and industrialized food, animal fat (dairy, meat), gluten and sugar. Overall, allowed foods in liberal quantities are those prepared at home from readily available ingredients such as fruits, vegetables, fish and shellfish, poultry, oats, eggs, non-gluten grains and legumes. Tasty\&Healthy is not a specific diet; it is a dietary approach in which the allowed foods are not structured or restricted. This approach allows flexibility to increase adherence In this study, The Investigators hypothesize that the Tasty\&Healthy dietary approach will alter the risk of CD as reflected by a decrease in the GEM CD risk score or alteration of its individual components.