Abstract Body

Nutritional epidemiology and research in animals highlight the critical role of diet in development of Crohn’s disease (CD) and initiation of gut inflammation, respectively. In active and pre-surgical CD, exclusive enteral nutrition (EEN) is a highly effective therapy, but it is a treatment that is difficult to adhere to and is therefore unsuitable for long-term disease maintenance. Hence, over the past 3 decades there has been several attempts to develop new dietary therapies to induce and prolong disease remission. There are more than 20 dietary therapies reported in the peer-reviewed literature for the management of CD. Some of these dietary therapies aimed to exclude food believed to cause inflammation within animal experiments, such as food additives, processed food and read meat, others aimed to introduce a diet which align to the principles of the Mediterranean diet, increase fibre and very few studies aimed to correct microbial dysbiosis, typical of CD. CDTREAT is a solid-food based diet which aims to mimic the composition of EEN and its effects on the gut microbiome. Most of the studies which explored the effectiveness of these novel dietary therapies for CD, explored their efficacy on six different efficacy outcomes, including clinical disease activity, quality of life, gastrointestinal symptoms, blood inflammatory markers, faecal calprotectin (FC) and endoscopic/imaging scores. Very few studies explored the effectiveness of these dietary therapies on objective biomarkers of gut inflammation. It is noteworthy that the efficacy of a significant number of diets has only been described in a single publication. Most diets reported improvements in disease activity scores; nonetheless, the efficacy signal is less encouraging for the effect of these diets on objective disease activity biomarkers. The CD exclusion diet coupled (CDED+PEN) with 50% partial enteral nutrition plus 5 daily mandatory foods is the most popular diet with replication by independent groups within RCT. The specific carbohydrate diet and Mediterranean diet failed to improve inflammatory biomarkers in an RCT in adults with Crohn’s disease. CD-TREAT demonstrated efficacy in a very small number of children with CD, but results from larger studies are imminent. While there is promise in this area, the current available evidence does not allow us to draw firm conclusions and recommendations regarding the efficacy of food-based dietary therapies on the management of CD; perhaps with the notable exception of CD exclusion diet with 50%PEN and the daily consumption of mandatory food. Limitations of current dietary research include the bias of placebo effect, particularly when authors report improvement in disease activity scores in patients with mild active disease. Compliance to dietary interventions is also poorly or inadequately described; mostly with self-reported dietary intake which is inherent to recall and misreporting bias. In this emerging area of clinical research and considering the inherent limitations of dietary research and assessment of disease activity objectively in IBD, replication of study results is of utmost importance before drawing conclusions on efficacy of any dietary treatment. Exclusive enteral nutrition remains a very effective induction treatment but with the advent of biological therapies fewer patients are expected to be treated with EEN, and in the future it is likely we will see a higher use of EEN in combination with other induction therapies and for presurgical use.