Dietary Therapy for IBD

By Dr Emma P. Halmos

About the Author

Dr Emma P. Halmos is an Accredited Practising Dietitian, and Adjunct Senior Research Fellow, Department of Gastroenterology, The Alfred Hospital and Monash University.

Almost every person diagnosed with inflammatory bowel disease (IBD) will ask the question: “What should I eat?”

Historically, diet was dismissed by healthcare professionals, with the exception of using it to treat malnutrition or prevent bowel obstruction.  However, research over the last 10 years has brought to light how valuable diet is throughout different stages of IBD.  From research we have learnt that diet can be manipulated to target different aspects of IBD and should be considered part of routine IBD management. 

There are four ways in which diet may be used to treat IBD, as detailed below:

  1. Nutritional adequacy: Malnutrition, which describes both under- and over-nutrition, is very common in IBD, particularly in people with active Crohn’s disease, due to increased requirements from inflammation and possible impairment of nutrient absorption with small bowel involvement.  Malnutrition is not a trivial problem and can cause fatigue, poor quality of life, depression and may even weaken response to certain medications.  Furthermore, people with malnutrition are more likely to become sick and take a longer time to recover.  This is of particular concern for those undergoing surgery, as malnutrition contributes to risk of post-surgical complications.  Unfortunately, weight is not the best indicator of malnutrition, but unintentional weight loss of more than 5% body weight within three months is a sign of undernutrition.  If you are malnourished, it is recommended that you see a dietitian who can help change your diet to achieve good nutritional status. 
  2. Dietary treatment for inflammation:  Treatment of an active disease is mainly done with medications.  The only dietary therapy that has shown to effectively treat adults and children with active Crohn’s disease is exclusive enteral nutrition (EEN).  This is a short-term treatment that involves drinking nutritional supplements in place of food, usually for six weeks.  EEN must be used under the guidance of both a gastroenterologist and IBD dietitian to ensure it is done correctly and that there is a plan in place for when EEN is stopped.  Since the emergence of EEN, there are many other diets being developed and formally investigated in research trials for their effectiveness to treat Crohn’s disease and/or ulcerative colitis.  It is likely there will be more valid evidence-based dietary therapies available in the future.  On the other hand, some diets that are often promoted on the internet without undergoing formal research trials also claim to treat IBD.  Many of these diets can be extremely restrictive and cause malnutrition and they use only symptoms as a marker of inflammation, which is not always accurate (see below).  Your gastroenterologist and dietitian can discuss options of dietary management with you. 
  3. Complications of IBD:  Sometimes dietary therapies may be used to treat other problems resulting from IBD.  Many people with IBD also develop irritable bowel syndrome (IBS), which means symptoms are related to how the bowel is functioning rather than from inflammation.  This is why it is important to not rely on only symptoms to determine inflammation, but also objective markers.  Medications for IBD target inflammation, so they tend not to work on IBS.  Alternatively, certain diets, such as a FODMAP diet, can improve symptoms, but not inflammation.  Other IBD complications that may need specialty diets include strictures (intestinal narrowing), fat malabsorption, oxalate kidney stones or for symptoms from altered bowel anatomy (e.g., ileostomy, colostomy or j-pouch). 
  4. Preventing IBD:  Most research into IBD and diet have looked at very large studies that link dietary components to development of IBD in healthy people.  Evidence suggests that features of a Mediterranean diet, such as large amounts of plant-based foods (grains, vegetables and fruit), moderate amounts of dairy and fish, and limited meat is protective against Crohn’s disease and less meat also protective against ulcerative colitis.  On the other hand, discretionary food (i.e., ‘junk food’) increases risk of developing IBD.  While these dietary factors are recommended for those at risk of getting IBD, such as family members of those with known IBD, we do not know if these suggestions treat established IBD. 

Dietary therapy in IBD is used now more than ever before.  As dietary recommendations for IBD patients are individual and depend on the purpose, guidance through an IBD dietitian is advised.  Indeed, access to a gastrointestinal dietitian is now recommended as part of IBD management by Australian and global IBD quality of care standards.  To ensure that you are adapting diet effectively and safely, discuss with your IBD treating team the need of involving a suitable dietitian. See, an Australian network of IBD dietitians for further information.