Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) affecting millions globally, marked by inflammation in the digestive tract and symptoms like abdominal pain, diarrhea, weight loss, and fatigue. Dietary therapy is now a recognized strategy for managing CD, with exclusive enteral nutrition (EEN) often the first line of treatment for pediatric cases. This article delves into the Crohn's Disease Exclusion Diet (CDED), a whole-food approach designed to reduce exposure to dietary components that may trigger inflammation.
Understanding the CDED
The Crohn's Disease Exclusion Diet (CDED) is a whole foods diet designed to exclude or limit exposure to foods that may adversely affect the microbiome or alter intestinal barrier function. The CDED aims to reduce exposure to dietary components that are potentially pro-inflammatory, mediated by negative effects on the gut microbiota, immune response, and the intestinal barrier. This diet involves eating liquid formula as well as whole foods and avoiding foods that are thought to damage the gut. Potentially inflammatory foods might be avoided and then reintroduced, allowing you to identify whether they trigger your symptoms.
The CDED has emerged as an alternative to exclusive enteral nutrition for the treatment of pediatric Crohn’s disease. The CDED has emerged as a valid alternative to EEN with cumulative evidence, including randomized controlled trials, supporting use for induction of remission and possibly maintenance in children and adults. In patients uninterested or unable to use Exclusive Enteral Nutrition, CDED is an effective alternative for inducing remission, and it may provide a more effective option than standard diet plus PEN for maintaining it.
Goals of the CDED
- Reduce inflammation in the digestive tract.
- Promote gut healing.
- Prevent symptom flare-ups.
- Identify individual trigger foods.
CDED Phases and Food Lists
The CDED involves eating whole foods as well as liquid foods. Throughout the diet, you’ll cut out foods that may irritate your gut and gradually reintroduce some of those foods. This allows you to identify potential trigger foods. The CDED is managed a little differently from the other diets. The CDED is divided into three phases. The first two 6-week phases are grouped together as the Induction Phase, which is used for inducing remission. The Maintenance Phase is used after remission is achieved and is intended to sustain that remission. The diet is broken up into three 6-week phases, each with a slightly different eating plan. Partial enteral nutrition (PEN), a liquid formula, is allowed in every phase.
The food list provided is a simplistic overview of the basic requirements of the diet, offering a bird's eye view of restricted and allowed foods. It is not an all-inclusive list of the allowed and restricted foods, nor does it define all the rules of the diet. Consult with a dietitian trained in CDED.
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Phase 1 (Weeks 1-6): Strict Elimination and Healing
The first six-week phase of the Induction Phase limits insoluble fiber to prevent bowel obstructions. The first phase (weeks 0-6) is highly restrictive, excluding all potential triggering ingredients, while emphasizing consumption of high-quality protein sources and microbiome-enhancing ingredients.
In addition to PEN, you can eat:
- Chicken breast
- Fish
- Lean meats
- Olive oil
- Onion
- Potatoes
- Rice
- Tomatoes
You can also have small quantities of:
- Apples
- Avocados
- Bananas
- Carrots
- Citrus juice
- Lettuce
- Melon
- Spinach
- Strawberries
Phase 2 (Weeks 7-12): Reintroduction and Monitoring
The second 6-week phase adds back in many of these vegetables by week 10. The diet is liberalized for weeks 6-12 (phase 2), enabling a gradual introduction of previously restricted components. During phase 2, you can eat the foods from phase 1 as well as PEN.
Your clinician might also suggest adding portions of foods like:
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- Certain legumes
- Certain fruits, including blueberries, kiwis, and peaches
- Certain vegetables, including broccoli, cauliflower, sweet potato, and zucchini
- Oats
- Whole-grain bread and pasta
Phase 3 (Weeks 12 and Beyond): Long-Term Management
Phase 3 is considered the “maintenance phase” of the diet. The third maintenance phase follows from week 13 for at least 9 months, until a more personalized approach is established. In addition to liquid nutrition and foods from the other phases, you might reintroduce the following foods at allotted portions:
- Alcohol
- Coffee
- Dairy
- Grains
- Seafood
You may be required to keep a food diary to help you identify trigger foods. If your symptoms flare up during the maintenance phase, your clinician or dietician might suggest returning to phase 1.
Key Considerations for CDED
- Individualization: Every person’s triggers and tolerance levels are unique.
- Professional Guidance: It’s best not to follow the diet on your own, but rather to rely on the guidance of a registered dietician or another qualified healthcare practitioner.
- Food Diary: You may be required to keep a food diary to help you identify trigger foods.
- Meal Preparation: Prepare compliant meals and snacks in advance to avoid accidentally resorting to non-compliant options.
- Symptom Tracking: Track your meals and symptom patterns in a notebook or app.
- Gradual Transition: Gradually transition to the exclusion diet instead of going all-in on day one.
- Hydration: Dehydration is common among Crohn’s patients, especially during flare-ups.
- Community Support: Connect with others managing Crohn’s disease through local meetups or social media communities.
- Cooking Methods: Baking, steaming, and boiling tend to make foods easier to digest.
CDED Research and Efficacy
After 6 weeks, 76.7% of participants achieved clinical remission, which means that their symptoms significantly reduced. This number increased to 82.1% after 12 weeks of therapy. A 24-week study compared two groups with one another. One group followed the diet along with a nutritional drink while the second group followed the diet only. With or without the nutrition drink, the diet effectively reduced symptoms.
The effects of the six-week induction phase of CDED were first reported in pediatric Crohn's disease in 2014. The 12-week induction phase in children and adults failing biologics was reported in 2017 with a comparison of CDED + PEN vs EEN in 2019 and data in adults with Crohn's disease in 2021.
CDED vs. EEN
Compared with other options, CDED may be easier to stick to. Crohn’s disease is often treated with a liquid-only diet called exclusive enteral nutrition (EEN). Although EEN can be effective, it can be difficult to adhere to because it involves avoiding all solid foods. CDED is less restrictive than EEN because it includes liquid nutrition as well as certain solid foods. This means people might find it easier to comply with CDED, reducing their risk of going off-plan and eating items that might trigger their symptoms.
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The Role of the Multidisciplinary Team
We gathered a group of multidisciplinary experts, including pediatric and adult gastroenterologists, inflammatory bowel diseases (IBD) expert dietitians, and a psychologist to discuss the evidence, identify gaps, and provide insights into improving the use of CDED based on a comprehensive review of CDED literature and professional experience. The primary goal of any nutritional therapy is to optimize the patient’s nutritional and clinical status while supporting growth and development. This can be achieved by tailoring the therapy to the individual patient’s needs, while simultaneously improving dietary adherence.
The involvement of trained dietitians becomes crucial in this context, as they possess valuable insights into patients’ habits, limitations, and potential development of negative relationships with food, including avoidant restrictive food intake disorder (ARFID). In certain cases, dietitians may guide patients towards a less restrictive diet and collaborate with psychologists to improve food-related behaviors.
Adapting CDED for Different Populations
The CDED was designed to be adaptable across various countries and cultures, incorporating simple and internationally accessible foods. Recent clinical studies on the implementation of a modified CDED in various populations exemplifies how this nutritional therapy has been adapted to diverse food cultures, religious practices, and individual nutritional needs, while maintaining alignment with national dietary guidelines and achieving improved adherence. These adaptations have showed improved individualization, acceptability, and adherence to the diet.
Nordic-CDED Adaptation
To date, data on adaptations of the CDED within the Scandinavian settings are limited, and its clinical application remains scarce. This article presents the theoretical rational for an adaptation of the CDED to a Nordic modification. A key aspect of this adaptation involves a comprehensive review of the core principles and rationale of the original CDED.
The Nordic diet is characterized by native berries, legumes, apples, pears, root vegetables, cabbage, cauliflower, curly kale, and mushrooms, as well as whole grains such as barley, wheat, oats, buckwheat, and rye. It also includes regular fish consumption, seaweed, and free-range animal products. Given these core foods in the Nordic diet, it is theoretically possible to incorporate a wider variety of foods across the different phases of the CDED, while still maintaining its presumed anti-inflammatory benefits and ensuring adequate nutritional intake.
The modified Nordic-CDED incorporates current EFSA regulations on food additives and aligns with the Nordic Nutrition Recommendations to tailor nutritional requirements to individual needs. The primary goal of this adaptation is to support the individualization of the CDED.
Potential Challenges and Considerations
- Disordered Eating: Any diet or eating plan, whether prescribed by a clinician, can carry the risk of triggering or aggravating disordered eating patterns (and, potentially, eating disorders). If you have a history of disordered eating, or if you’re concerned that following an exclusion diet might affect your relationship with food, talk with your healthcare practitioners about it.
- Effectiveness: It’s possible that the CDED won’t work for you. Although research has shown it to be effective for most participants, it doesn’t work in every case. It can be discouraging if it doesn’t improve your symptoms, but there are a variety of other diets that you could try.
- Compliance: Interestingly, even patients who did not make it through to CDED stage 3 reported significantly changes in their everyday diet and consumed less processed foods.