How much can targeted diets help treat chronic inflammatory bowel disease (IBD)? Clinical studies suggest that certain dietary approaches can induce remission in about 50% to 80% of patients, Sandra Ulrich-Rückert, PhD, a nutrition scientist at Goethe University Frankfurt, Frankfurt am Main, Germany, reported at the 132nd Congress of the German Society of Internal Medicine held in Wiesbaden, Germany.
The interaction between IBD and eating habits is complex: It ranges from possible involvement in disease pathogenesis to disease‑associated malnutrition and to diet as a therapeutic option at different stages of the disease. The Western dietary pattern — many additives in highly processed foods and a high share of saturated fats and red meat, especially processed red meat — appears to play a substantial role in disease development. “However, we are not yet at the point of being able to say which specific factors are responsible,” Ulrich‑Rückert cautioned.
It is suspected that additives influence the microbiome, promote dysbiosis, and can affect barrier function. Emulsifiers, for example, are suspected of increasing intestinal permeability. For prevention, the S3 guideline “Clinical Nutrition in IBD” of the German Society for Nutritional Medicine recommends a vegetable‑rich diet high in omega‑3 fatty acids and low in omega‑6 fatty acids, which is associated with a lower risk of developing IBD. Breastfeeding for at least 6 months also reduces the risk of IBD. Attention should be paid to a healthy body weight because obesity increases the risk of developing Crohn’s disease.
Warning: Malnutrition Is Common
The guideline points out that malnutrition occurs frequently in IBD, especially during flare-ups. The main effects of malnutrition are weight loss, often protein deficiency, and anemia caused by deficiencies in iron and folate, but also vitamin B12. Malnutrition can lead to many negative consequences:
More frequent IBD exacerbationsMore frequent hospital admissionsMore frequent serious infectionsA risk factor for nonelective surgeryLonger hospital staysMore frequent postoperative complicationsIncreased mortality
Early screening for malnutrition — at diagnosis, every 6 to 12 months, whenever clinical status changes, and before surgery — is therefore important. Ulrich‑Rückert named suitable screening tools such as the Nutritional Risk Screening tool, the Malnutrition Universal Screening Tool, the Global Leadership Initiative on Malnutrition criteria, and the Subjective Global Assessment.
Diet as Therapy
Which dietary approach can support IBD therapy? The best-known and most established is exclusive enteral nutrition (EEN). EEN eliminates possible proinflammatory factors, simultaneously corrects potential malnutrition, and is thought to allow correction of possible dysbiosis. “The studies show that EEN for induction of remission is comparable with steroids, and rates of mucosal healing are even higher: 89% vs. 17%,” Ulrich‑Rückert reported.
EEN also improves nutritional status, modulates the microbiome, and is free of side effects. However, it requires close monitoring and intensive patient education, and it lacks a clear exit strategy. The biggest problem is compliance: While it is still relatively feasible in children, EEN has not really become established in adults — dropout rates are high, and long‑term success is limited.
Dietary Remission Strategies
Among the many dietary approaches for IBD, the Crohn’s disease exclusion diet (CDED) is the most established. EEN serves as the foundation, and specific foods are permitted. Animal fats may be eaten only very sparingly; wheat and gluten are prohibited; dairy products and red meat are also excluded. Foods must contain no additives and must not be processed.
CDED consists of three phases:
Phase 1 includes 50% oral nutritional formula and restricted whole foods for 6 weeks. There are mandatory foods that must be eaten every day, in addition to permitted foods, some in limited quantities.Phase 2 expands the food choices.Phase 3 moves closer to a Mediterranean diet and discontinues the oral nutritional formula.
Results from a study of CDED’s effectiveness in adults show that remission is achieved in 60% to 80% of patients after 6 weeks. CDED is recommended in guidelines (the ESPEN Guideline on Clinical Nutrition in Inflammatory Bowel Disease and the DGEM guideline).
CD‑Treat uses an individualized, food‑based diet whose composition is very similar to EEN. The diet had the same effect on the microbiome, inflammation, and clinical response in children and adults as classic EEN. However, the study included 25 healthy adults and only five children with active Crohn’s disease (all of whom received CD‑Treat). CD‑Treat achieved a remission rate of 60%. Study participants received meals via catering. Ulrich‑Rückert said implementation of this approach in routine patient care would be difficult.
The Tasty & Healthy diet (T&H) avoids processed foods, gluten, red meat, and dairy products except yogurt and is modeled on the concept of “clean eating.” “Everything that is not forbidden is allowed — as long as it is unprocessed,” Ulrich‑Rückert said. In the study, the T&H diet was compared with EEN and after the first 8 weeks showed a symptomatic remission of 56% vs 38% by the EEN. There were minimal differences in fecal calprotectin (< 250 μg/g, 34% vs 33%) or in mucosal healing (44% vs 31%).
Ulrich‑Rückert reported that the T&H diet increased microbiome diversity, whereas EEN tended to reduce diversity. Acceptance and adherence were substantially higher in the whole‑food group — 88% vs 52%. Nevertheless, because of its clearer, more structured protocol, she prefers the CDED.
The diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols restricts poorly absorbed short‑chain carbohydrates (FODMAPs) to reduce gas production. “As to the evidence in IBD, we have no indications of anti‑inflammatory effects or induction of remission in active IBD,” Ulrich‑Rückert emphasized. Nevertheless, the low-FODMAP diet reduces abdominal pain, bloating, and diarrhea. For patients with IBD, it may be considered only short‑term and only when the disease is inactive, particularly if overlapping irritable bowel syndrome symptoms are present.
Maintaining Remission
The Mediterranean diet is suitable for maintaining remission. Half of daily intake should come from more vegetables than fruits, one quarter from protein‑rich foods, and the remaining quarter from carbohydrates, preferably whole grains.
Ulrich‑Rückert concluded that if a qualified specialist is certified and you, the physician, issue a Medical Certificate of Necessity, nutritional therapy will be covered by statutory health insurers in Germany.
This story was translated from Medscape’s German edition.