Crohn’s disease is a type of inflammatory bowel disease (IBD) that is characterized by inflammation in the lining of the digestive tract. It can occur at any point throughout the GI tract, but is most often seen in the ileum (the last section of the small intestine) as well as the beginning portion of the large intestine.
This type of IBD can lead to a variety of symptoms including diarrhea, abdominal pain & cramping, blood in the stool, unintentional weight loss, fatigue, and lack of appetite. If Crohn’s disease is not well managed, it can be challenging for patients to meet their nutrient needs. Malnutrition is common because of these things.
It is important that dietary interventions for Crohn’s disease focus on both improving symptom outcomes and correcting nutritional deficiencies. Not only that, but the best therapies for Crohn’s disease should attempt to improve the underlying disease activity (ie. the inflammation itself) rather than just correct symptoms at the surface. But the real question is this: Can we actually reduce inflammation in the GI tract with diet? We’ll come back to this theory – but first, let’s talk about the more common therapy for reducing inflammation in Crohn’s disease patients – medication.
Medications for Crohn’s disease
The first line therapy for IBD patients is medications that have been shown to reduce inflammation in the intestinal lining, promote mucosal healing, and overall improve quality of life.
This includes various classes of medications, with the main options being:
While these types of medications have generally good success rates for inducing disease remission, the true challenge seems to be that achieving long-term remission is difficult, even with medication use. Additionally, many of these medications come with side effects that aren’t all that fun. Furthermore, there are some patients that simply don’t respond at all to pharmacological therapies.
Where does diet fit?
Recent research has shown that diet CAN indeed impact disease activity and plays a role in improving the integrity of the gut lining and the intestinal immune response.
According to the literature, one of the strongest diets for achieving remission of Crohn’s disease is exclusive enteral nutrition (EEN) – ie. consuming ONLY a liquid diet of a prescribed nutritional formula for 4-12 weeks.
Let’s be honest – this isn’t a sustainable approach for most people. It is extremely difficult for most people to maintain a liquid-only diet. Most of the research looking at EEN as a therapeutic option has been done in pediatric populations, and the results are less conclusive in adult populations.
To maintain a sense of dietary normalcy and improve quality of life in patients, a less restrictive version of the liquid-only enteral nutrition diet has emerged called the Crohn’s Disease Exclusion Diet with Partial Enteral Nutrition (CDED + PEN). Let me tell you more!
Crohn’s Disease Exclusion Diet + Partial Enteral Nutrition (CDED + PEN)
Just as it sounds, partial enteral nutrition involves liquid nutrition formulas too, but only as part of the diet, rather than the entire diet. These nutrition formulas are consumed orally – no tubes or complicated set-ups needed! These nutritional drinks are used in combination with eating solid foods as well. This combination of nutrition formula and real foods makes this diet less restrictive and better for the patients’ quality of life overall.
Not only does the Crohn’s Disease Exclusion Diet involve real foods, but a particular group of whole foods that are specifically chosen to promote mucosal healing. Certain components in foods have been purported to impair immunity, cause dysbiosis of the gut microbiome, and increase intestinal permeability – all characteristics that can impair mucosal healing in patients with Crohn’s disease. Therefore, the CDED involves eliminating many foods, particularly during the first two phases of this three-phase diet to allow the gut to heal. Each phase of the diet is also consumed in combination with PEN, with more calories coming from enteral formula at first, then gradual transition to more solid foods as the diet progresses.
Retrospective analysis studies show that this diet can induce remission and mucosal healing in approximately 70% of children and adults treated with this method. It may also be a useful treatment to induce remission in patients who are failing with biologic therapies.
The Three Phases: All You Need to Know About CDED + PEN
As mentioned above, CDED + PEN involves three different stages, starting with the most restrictive and transitioning to the least restrictive as the disease state improves. In each phase of the CDED, there is a list of mandatory foods, allowed foods, and disallowed foods. Mandatory foods are foods that each patient should consume daily to ensure adequate intake of protein, and important prebiotics to feed probiotic bacteria – particularly certain carbohydrates called resistant starch and pectin.
Allowed foods are additional ‘safe’ foods that can be sprinkled in throughout the day or week for added flavour and variety. Some allowed foods come with specific recommended portion sizes, while others are unlimited. In particular, many vegetables and fruit portions are kept small in phases 1 and 2 to keep fibre intake moderate.
Disallowed foods are foods and ingredients that are more likely to negatively affect mucosal healing and should be avoided. If a food is not listed in the ‘mandatory’ or ‘allowed’ groups for a specific CDED phase, it should be assumed it is disallowed during that particular phase of the diet. The list of disallowed foods does get smaller as the diet progresses, making it easier for patients to adhere to the diet over time.
Curious about which foods fall into which categories? Let’s learn more about each phase of CDED + PEN!
Phase 1: Weeks 0-6
In this phase, enteral nutrition makes up 50% of the patient’s caloric intake. The other 50% of intake comes from allowed and mandatory foods.
Mandatory foods in phase 1 of the diet are:
- Fresh chicken breast (unlimited quantity with a minimum of 150-200 grams/day) OR this can be swapped for lean fresh fish once per week
- 2 eggs per day
- 2 fresh potatoes per day (peeled, cooked and refrigerated before use)
- 2 bananas per day
- 1 apple per day (peeled is generally tolerated best)
The list of allowed foods is longer, with several options to increase variety in the diet beyond just the mandatory foods listed above.
Some examples of additional allowed foods in phase 1 are:
- white rice
- peeled cucumbers
- fresh spinach
- olive oil
- fresh herbs
- herbal teas
Some examples of disallowed foods during this phase include:
- fried foods
- beef and pork
- dairy products
- soy products
- soft drinks
- processed foods
- packaged goods
- canned foods
Basically anything that is not listed in the allowed group, is assumed to be disallowed for the first 6 weeks.
Phase 2: Weeks 7-12
In this phase, enteral nutrition makes up 25% of the patient’s caloric intake and they are allowed to expand the amount of solid foods in their diet to 75% of their intake.
Mandatory foods in phase 2 of the diet are the same as those listed in phase 1, however the list of additional allowed foods expands to include even more variety, adding foods like canned tuna, sweet potato, whole grain bread, quinoa, oatmeal, pear, blueberries, and new types of vegetables like zucchini and mushrooms. Portions of fruits and vegetables in this phase are still limited overall, to avoid high intakes of fibre as the gut continues to heal. Peeling certain fruits and vegetables may also be recommended depending on the patient’s unique symptoms.
Phase 3: Weeks 13+ (lifelong maintenance phase)
In this phase, enteral nutrition also makes up 25% of the patient’s caloric intake BUT the maintenance diet is overall less restrictive than phases 1 and 2 and is meant to be followed long-term to maintain remission. There are no mandatory foods that need to be consumed every day in this phase, just allowed and disallowed foods.
This phase centers around a weekend vs. weekday approach – where more foods can be consumed on the weekend (or 2 select days each week). For the remaining 5 days, the patient is supposed to remain on the more strict version of phase 3.
What new reintroductions do we see in phase 3?
Fruits and vegetables – patients are able to expand their diet to include almost all fruit and vegetables and are encouraged to do so!
However, there are still a select few that should be avoided long-term:
- cactus fruit,
- raw celery,
- leeks, and
- large amounts of kale.
These are seedy, stringy, or have a lot of difficult-to-digest roughage which can influence symptoms. Wider variety of proteins – patients can expand beyond chicken breast and fish to other cuts of chicken (thighs, legs), as well as more seafood. Additionally, plain yogurt without additives can be added. Carbohydrate-rich foods – in addition to the foods allowed in phase 2, patients can also include extra whole grain bread (2 slices instead of 1) and some pasta. Coffee and tea – 1 cup of either each day
As you can tell, this diet is complex and there are a lot of restrictions and rules to follow. While we don’t suggest following rigid diets in most cases, there is a select group of people who could really benefit from CDED + PEN. However, this is NOT for everyone. If you have an eating disorder history or struggle with your relationship with food, there may be less restrictive solutions for you to manage your Crohn’s disease.
Also keep in mind, this diet requires a specific prescribed amount of enteral nutrition formula to meet your needs each day. You should always work with a dietitian when following CDED + PEN, as a dietitian can adequately assess and calculate the type and amount of formula you will need to consume each day to maintain adequate caloric intake and meet your micronutrient needs as well.
The nutrition formula required for CDED + PEN is also expensive, but can often be covered or partially covered by health insurance. A registered dietitian can help to coordinate with your doctor to prescribe the best option for you.
If CDED + PEN is something you’d like to learn more about, chat with one of our registered dietitians today!