What is the CDED diet? Your guide to the Crohn's Disease Exclusion Diet

According to recent studies, the Crohn's Disease Exclusion Diet (CDED) has shown significant promise, with some pediatric patients achieving clinical remission rates comparable to those on Exclusive Enteral Nutrition. But what is the CDED diet and how does it work to manage active inflammation and improve gut health?

Quick Summary

The CDED is a structured, phased dietary therapy for Crohn's disease. It uses a combination of specific whole foods and partial enteral nutrition to reduce inflammation, heal the gut, and induce or maintain remission.

Key Points

• Phased Approach: The CDED is a structured, three-phase dietary plan designed to reduce inflammation and promote gut healing in Crohn's disease.

• Food + Formula: It combines a specific whole-food diet with Partial Enteral Nutrition (PEN) in the initial phases, unlike the formula-only Exclusive Enteral Nutrition (EEN).

• Better Tolerated: Studies show CDED is often better tolerated and leads to higher compliance than EEN, as it allows for some solid foods.

• Microbiome Focus: The diet works by excluding inflammatory foods and including beneficial components like resistant starches to positively influence the gut microbiome.

• Promising Remission Rates: Clinical trials have shown high rates of remission, particularly in pediatric and adult patients with mild to moderate Crohn's disease.

• Medical Supervision Required: Due to its complexity, the CDED should be undertaken with professional guidance from a gastroenterologist and a registered dietitian.

The Science Behind the CDED Diet

The Crohn's Disease Exclusion Diet (CDED) is a novel dietary treatment that has emerged as a promising alternative for managing Crohn's disease, particularly for those with mild to moderate disease activity. Unlike Exclusive Enteral Nutrition (EEN), which relies solely on liquid formulas, the CDED combines formula with a selective, food-based diet. The core principle is to exclude or limit foods believed to trigger or worsen inflammation, while including foods that support gut healing and a healthy gut microbiome. This structured approach is implemented over three distinct phases, becoming progressively more liberal with time.

The Role of the Gut Microbiome

Research indicates that patients with inflammatory bowel disease (IBD) often have an imbalanced gut microbiome, a condition known as dysbiosis, which contributes to inflammation. The CDED addresses this by removing dietary components that may adversely affect the microbiome and gut barrier function. Concurrently, it promotes the intake of beneficial components, such as prebiotic fibers and resistant starches found in fruits and cooked-then-cooled potatoes. These components are used by beneficial gut bacteria to produce short-chain fatty acids, which are thought to promote gut healing. A study comparing CDED plus Partial Enteral Nutrition (PEN) to EEN found that the CDED group showed a beneficial shift in their gut microbiome, with a reduction in inflammation-associated Proteobacteria.

Reducing Intestinal Inflammation

Clinical studies have demonstrated that the CDED effectively reduces markers of intestinal inflammation. For example, research has shown significant decreases in levels of C-reactive protein (CRP) and fecal calprotectin (FCP), both of which are indicators of inflammation in Crohn's disease. The strict elimination phase starves the inflammatory pathways, while the gradual reintroduction of whole foods helps to rebuild and restore normal gut function over time.

The Three Phases of the CDED

This diet is structured around three distinct, six-week phases, each carefully designed to progress from strict exclusion to long-term maintenance.

Phase 1: Induction (Weeks 1-6)

This is the most restrictive phase, combining a specific diet with Partial Enteral Nutrition (PEN), which provides 50% of the patient's total energy intake. The goal is to rapidly reduce inflammation. Allowed foods are strictly limited to a mandatory list plus a few others:

• Mandatory Foods: Fresh, skinless chicken breast; eggs (typically two per day); potatoes (cooked and cooled); peeled and cooked apples; and bananas.
• Other Allowed Foods: White rice, canned tuna in oil, specific fruits (strawberries, melon), limited vegetables (peeled carrots, spinach, cucumber, lettuce), avocado, and olive or canola oil.
• Exclusions: A wide range of foods are temporarily excluded, including red meat, dairy, gluten-containing grains, processed foods, and most fruits and vegetables.

Phase 2: Transition (Weeks 7-12)

As symptoms improve, this phase introduces more food variety while reducing the reliance on formula. PEN is typically decreased to 25% of the daily caloric intake.

• Expansion of Allowed Foods: The diet adds more vegetables (zucchini, mushrooms, broccoli, cauliflower), fruits (pears, peaches, kiwis, blueberries), and small amounts of grains like whole-grain bread and gluten-free oats.
• Controlled Reintroduction: Small, controlled portions of foods like lean red meat and legumes may also be introduced.

Phase 3: Maintenance (Weeks 13 onwards)

This phase focuses on sustaining remission without the need for enteral nutrition. It allows for a more varied diet while continuing to limit or avoid known inflammatory triggers and processed foods.

• No PEN: The diet is fully food-based, although monitoring is still crucial.
• Varied Whole Foods: A wide array of whole foods are permitted, with some exceptions still in place.
• "Free" Meals: The diet allows for a small number of controlled "free meals" per week to improve long-term adherence.

CDED vs. Other Crohn's Disease Diets: A Comparison

Feature	CDED (Crohn's Disease Exclusion Diet)	EEN (Exclusive Enteral Nutrition)	Low-FODMAP Diet	SCD (Specific Carbohydrate Diet)
Use of Liquid Formula	Combines specific whole foods with Partial Enteral Nutrition (PEN), gradually phasing out formula.	Uses only a liquid formula for a fixed period (6-8 weeks); no solid foods allowed.	No liquid formula is used; focuses entirely on food-based restriction.	No liquid formula is used; focuses on restricting certain carbohydrates.
Food Flexibility	Starts restrictive (Phase 1) but progressively expands food choices in later phases, focusing on whole foods.	Extremely restrictive; no solid food is consumed for the duration of the induction phase.	Restrictive initially to identify triggers; reintroduction is based on individual tolerance, but not structured over specific phases.	Highly restrictive, eliminates all grains, processed foods, lactose, and more.
Suitability for Long-Term Use	Designed with a maintenance phase for sustainable, long-term dietary management.	Not intended for long-term use, as it is unsustainable to have no solid food.	Can be managed long-term, but careful reintroduction is necessary to avoid unnecessary restriction.	Requires lifelong adherence to a very strict list of 'legal' foods.
Patient Compliance	Often better tolerated than EEN due to the allowance of solid foods.	Often difficult to adhere to due to the complete restriction of solid food.	Can be complex to follow and restrictive, but less so than SCD.	Very difficult for many people to adhere to long-term due to its strict nature.

Is the CDED Right for You? Consulting a Healthcare Team

Beginning the CDED requires careful planning and, most importantly, supervision from a healthcare team, including a gastroenterologist and a registered dietitian specializing in IBD. This professional guidance ensures that the diet is followed correctly, nutritional needs are met, and progress is properly monitored. This team can help tailor the diet to your specific needs and track inflammatory markers like CRP and FCP to measure effectiveness.

Benefits of Medical Supervision

• Personalized Planning: A dietitian can help create meal plans that fit your lifestyle and preferences while adhering to the diet's phases.
• Nutritional Adequacy: They can ensure you receive all necessary nutrients, especially important during the restrictive phases.
• Monitoring Progress: They can track your symptoms and inflammation markers to determine if the diet is working and when to safely progress to the next phase.
• Support and Accountability: Consistent support improves adherence, which is crucial for achieving and maintaining remission.

Conclusion

The Crohn's Disease Exclusion Diet offers a food-based pathway toward managing active Crohn's disease and sustaining remission, providing a promising alternative to exclusive liquid diets. By targeting the gut microbiome and reducing inflammatory triggers, the CDED has been shown to be effective, particularly in mild to moderate cases. Its phased structure, which includes both partial enteral nutrition and real food, contributes to better tolerability and long-term adherence. However, its successful implementation relies heavily on a patient's commitment and the close supervision of a healthcare team. As with any medical intervention, patients should discuss the CDED with their doctor and a specialized dietitian to determine if it is the right approach for their individual condition.

Learn more about dietary therapies for IBD from authoritative sources like the Crohn's & Colitis Foundation.

Frequently Asked Questions

What is the primary difference between the CDED and EEN diets?

The main difference is that EEN consists of only liquid formula for 6-8 weeks, whereas the CDED combines formula with a selective whole-food diet from the beginning, which many patients find easier to tolerate.

Who is the CDED diet best suited for?

The CDED is particularly effective for people with mild to moderate, uncomplicated Crohn's disease. It can be used to induce remission or maintain it, especially in treatment-naïve patients.

How long do the different phases of the CDED diet last?

Each of the first two phases lasts for six weeks. Phase 1 is the induction phase (weeks 1-6), Phase 2 is the transition phase (weeks 7-12), and Phase 3 is the long-term maintenance phase (weeks 13+).

What are the mandatory foods in the initial phase of the CDED?

In Phase 1, the five mandatory foods are fresh chicken breast, eggs, cooked and cooled potatoes, apples, and bananas. These are eaten alongside partial enteral nutrition.

Can I follow the CDED diet without using a liquid formula?

A small pilot study showed that the CDED diet without Partial Enteral Nutrition (PEN) was effective for some adults, but standard practice combines CDED with PEN for optimal results, especially for inducing remission. Consulting a dietitian is crucial.

Are there any processed foods or additives allowed on the CDED?

No, processed foods and additives like emulsifiers, preservatives, and artificial sweeteners are strictly excluded from the diet, especially during the induction and transition phases.

What happens if my symptoms return during the maintenance phase?

If symptoms return during Phase 3, a healthcare team may advise returning to a stricter phase, such as Phase 1 or 2, to regain control of the inflammation.