Can IBD be treated with diet alone?
IBD can be treated with diet alone – No, it cannot!
The cause of IBD is not completely understood, but we believe something in our environment triggers a dysregulated immune response in individuals with a genetic predisposition to IBD. Among the environmental triggers commonly recognized, diet is considered an important trigger through its ability to affect the composition and health of the gut microbiome and host barrier function. Epidemiologic data support this assumption. Westernization of diet has been associated with the increasing incidence of IBD across the globe and in immigrants who move from developing countries to an industrialized country. Observational studies have shown diets higher in meat and polyunsaturated fatty acids and omega-6 fatty acids are associated with a higher risk for IBD, whereas diets high in fruits, vegetables, and other sources of dietary fiber have a lower risk of IBD.
A growing body of evidence supports the impact food can have on gut health, specifically in mouse IBD models, but it is challenging to translate findings from animal studies into dietary interventions for IBD patients. Mouse studies help us understand the mechanistic basis of how diet may affect IBD, but randomized clinical trials establishing their role in IBD are lacking. This is not surprising as dietary studies are challenging, particularly if done in a robust manner, given the difficulties of ensuring and measuring dietary compliance.
Exclusive enteral nutrition (EEN) has been studied the most rigorously of all diets in IBD and has demonstrated the greatest benefit, compared with other diet studies in IBD. EEN requires the intake of elemental, semi-elemental, or polymeric formulas to meet all nutritional requirements without additional intake of food for 6-8 weeks. Studies have been performed mostly in pediatric populations and have shown effectiveness in induction of remission with reduction in inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin, and even mucosal healing. EEN has not worked out as well for adult populations, because of the poor tolerability of exclusive intake of enteral formulas. Because of this limitation, studies of partial enteral nutrition have been performed that generally allow some food intake in addition to the enteral nutrition. When compared with EEN or anti–tumor necrosis factor–alpha therapy, partial enteral nutrition is a less-effective treatment of Crohn’s disease; however, partial enteral nutrition does appear to improve clinical symptoms.
Beyond EEN, there are many diets that have been considered for the treatment of IBD, including the specific carbohydrate diet (SCD), Crohn’s disease exclusion diet, autoimmune diet, low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols), Paleolithic diet, Mediterranean diet, and the semi-vegetarian diet, to name a few. Of these, only the SCD and Crohn’s disease exclusion diets have shown improvement in clinical remission and reduction in inflammatory markers.
The SCD diet is based on the theory that malabsorption of disaccharide and polysaccharide carbohydrates leads to bacterial overgrowth and host barrier dysfunction. This diet eliminates grains, dairy, processed meats, and certain vegetables such as potatoes, yams, and legumes. Small uncontrolled studies have shown improvement in symptoms and endoscopy findings. However, this restrictive diet is nearly impossible to follow long term. The Crohn’s disease exclusion diet is a whole foods diet avoiding all processed foods, animal fats, dairy, and gluten. Small studies of this diet have also shown improvement in clinical symptoms and inflammatory markers.
The plethora of studies and reports of the therapeutic effect of diet on IBD provide some promise of the benefit dietary modifications can bring to our IBD patients. However, most dietary studies are underpowered, lack a control arm, and do not include endoscopic endpoints. The current body of evidence remains insufficient to support the use of diet alone for the treatment of IBD. We need randomized clinical controlled trials that are held to the same rigor as those of our approved medical treatments for IBD. Although such trials are challenging, we’ve seen groups rise to the task to carry out more robust dietary studies in the IBD population, and we await the results of several ongoing trials.
IBD is a challenging disease to live with and often leaves our patients feeling out of control. Dietary choices provide an avenue for patients to have some control of their health. However, current evidence does not support the prescription of dietary interventions alone to treat IBD, particularly when we have known, effective therapies. While I am not ready to prescribe diet as a stand-alone treatment for IBD, I make a point to discuss the role diet may play in helping our patients achieve optimal health. As health care providers, it is our responsibility to provide holistic care to our patients, which includes promotion of a healthy diet, absent processed foods and added sugars. Healthy lifestyle choices combined with effective medical and surgical treatments offer our patients the best shot at sustained disease control.
References
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Dr. Raffals is a gastroenterologist in the division of gastroenterology and hepatology, Mayo Clinic, Rochester, Minn. She has no financial conflicts of interest relevant to this paper.
