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Exclusive enteral nutrition is the first-line diet therapy to treat active Crohn’s disease.
The diet consists only of liquid nutrition that is provided by mouth or with the use of a feeding tube.
This article explains how exclusive enteral nutrition (EEN) works as well as its benefits and downsides for treating Crohn’s disease.
What is exclusive enteral nutrition (EEN)?
EEN is a liquid-only diet that provides all your calories and nutrition orally or by a feeding tube.
The diet is commonly prescribed for 6–8 weeks during active Crohn’s disease to induce remission, which means to decrease the signs and symptoms or make them disappear.
Crohn’s disease is a type of inflammatory bowel disease (IBD) that affects any part of the digestive tract.
Ulcerative colitis is another type of IBD, affecting only the colon or large intestine. EEN isn’t generally needed to manage ulcerative colitis.
There are three types of EEN formulas, each varying in their ease of digestion.
EEN formulas include (1):
- Elemental. This formula contains nutrients that have been broken down into their simplest form so they are easy to absorb.
- Semi-elemental. This formula contains nutrients that are partially broken down.
- Polymeric. This formula contains whole proteins, complex carbohydrates, and fat.
Some people may tolerate an elemental or semi-elemental formula better than a polymeric, but research suggests there is no significant difference among them in their effectiveness for inducing remission (2, 3).
Commonly used polymeric formulas include:
And although these enteral formulas may contain a variety of food additives that have been suggested to trigger or worsen symptoms such as certain starches and carrageenan, research suggests these ingredients don’t affect remission rates (6).
In either case, these formulas and their amounts are usually prescribed by a registered dietitian to meet all your calorie and nutrient needs, including vitamins and minerals.
They may come premixed or as a powder that you mix yourself.
EEN is safe and generally well-tolerated but may cause minimal side effects, such as nausea, abdominal pain, excessive gas, or diarrhea (7).
EEN has two primary benefits for active Crohn’s disease — it’s effective for inducing remission and it improves nutritional status.
It induces remission
EEN has been shown to induce remission in 80–85% of children and adolescents with Crohn’s disease (1).
It also reduces the need for corticosteroids to reduce inflammation. Corticosteroids are known to impair growth and immune function (8).
It’s believed that EEN induces remission in part by positively alterting the gut microbiota, which are the bacteria that live in the digestive tract (9).
When the richness and diversity of these bacteria become unbalanced, intestinal inflammation and subsequently the development or worsening of symptoms can occur.
EEN restores the balance of healthy gut bacteria and reduces intestinal inflammation, allowing for intestinal healing and symptom relief.
To this point, EEN has also been shown to relieve inflammatory bowel strictures, which occur when the bowels narrow and become scarred as a result of chronic inflammation (11).
By relieving inflammatory bowel strictures, EEN may reduce the need for surgery to correct the stricture.
It improves nutritional status
People with Crohn’s disease are commonly underweight and deficient in many nutrients, including iron, zinc, selenium, and vitamins B12, A, C, and D, among others (7).
The chronic inflammation that occurs with Crohn’s disease can decrease appetite and therefore food intake while also decreasing the absorption of certain nutrients from the digestive tract.
The medications used to lower inflammation such as corticosteroids can also decrease appetite and nutrient absorption while increasing the need for other nutrients like protein.
Restrictive diets and the symptoms associated with Crohn’s disease, such as abdominal pain, nausea, diarrhea, and fatigue, can also make it difficult to get enough nutrition.
Consequently, malnutrition is highly prevalent among people with Crohn’s disease, which decreases the body’s ability to fight infections and increases the likelihood of hospitalization and emergency surgery (12).
However, because EEN lowers intestinal inflammation and provides the necessary calories and nutrients your body needs, EEN has been shown to improve nutritional status and effectively treat malnutrition.
The downsides of EEN include its poor tolerability and low adherence. There are also limited studies conducted on adults, and symptoms tend to return with the reintroduction of whole foods following EEN.
Poor tolerability and low adherence
A downside of EEN is its poor palatability — if taken orally.
Although the taste and texture of enteral nutritional supplements have greatly improved over time, they can still be difficult to stomach for some people, especially when you have to drink multiple cartons daily.
Providing EEN by a feeding tube, that’s either inserted through your nose or directly into the stomach through the abdomen, can solve this problem but this route is not always preferred.
The EEN can also be difficult to follow long enough to experience remission.
Alternatively, a partial enteral nutrition (PEN) diet has been suggested as a solution to increase tolerance and adherence since it uses a combination of liquid nutrition — usually 35–50% of calories — and some whole foods that tend to be well tolerated by people with Crohn’s disease (13).
One study suggested that 70% of children and 69% of adults with Crohn’s disease achieved remission with PEN (14).
Another study in children demonstrated that PEN was better tolerated and just as effective for inducing remission as EEN (15).
In either case, EEN may be more effective than PEN in people with severe Crohn’s disease.
Few studies performed on adults
Another downside to EEN for Crohn’s disease is that most of the studies assessing its effectiveness for inducing remission were performed in children, not adults.
However, some researchers believe that there is no reason why the results would be different for adults.
To this point, EEN has shown promise in adults, but larger, high-quality trials are needed to determine its effectiveness compared with other alternatives like corticosteroids for inducing remission (5, 16).
Symptoms tend to return after EEN
EEN isn’t designed to be a lifelong dietary strategy for Crohn’s disease.
After remission is achieved with EEN, solid foods should be reintroduced, at which time, symptoms may return.
You may be able to prolong remission by slowly reintroducing foods, one at a time, to identify whether they trigger your symptoms (17).
One strategy is called the low fiber, fat limited exclusion (LOFFLEX) diet.
This diet restricts certain foods that are rich in fiber and fat for 2–4 weeks before reintroducing them back into your diet so you can identify foods that trigger your symptoms and avoid them going forward.
However, the research remains limited on its effectiveness for maintaining remission following EEN.
Other diets that have been suggested to reduce intestinal inflammation and alleviate symptoms of Crohn’s disease include:
The bottom line
EEN is an all-liquid diet that provides all nutrition by mouth or a feeding tube.
It’s prescribed to treat active Crohn’s disease, where it has been shown to induce remission after 6–8 weeks and improve nutritional status.
However, EEN tends to be poorly tolerated and most of the studies have been conducted on children, limiting the evidence to support EEN for achieving remission in adults with Crohn’s disease.
Symptoms tend to return after you achieve remission with EEN and reintroduce foods, but you may be able to prolong remission by slowly reintroducing foods, one at a time, so you can identify which ones trigger your symptoms.