Inflammatory Bowel Disease (IBD) is a chronic inflammatory condition that affects the gastrointestinal tract. The rising incidence of IBD has been associated with shifts toward a Westernized diet, and it’s thought that the gut microbiome may also play a role in its development. Because of the potential undesirable side effects of some traditional pharmacological therapies used to treat IBD, there is a growing interest in the use of dietary therapies to promote remission and healing of the gut. Today we will be reviewing enteral nutrition and the role it can play in helping induce and maintain histological remission in patients with IBD.
Inflammatory Bowel Disease
What is Inflammatory Bowel Disease?
The term Inflammatory Bowel Disease (IBD) is an umbrella term used to describe disorders in which the digestive tract is chronically inflamed. Two such disorders include Crohn’s disease and ulcerative colitis. Crohn’s disease is characterized by inflammation of the lining of the digestive tract and can often involve the deeper layers of the digestive tract. Crohn’s can occur at any point throughout the gastrointestinal tract, although is mainly present in the ileum and the start of the large intestine. ulcerative colitis is characterized by ulcerations along the outer lining of the large intestine (colon) and the rectum.
What are the Symptoms of Inflammatory Bowel Disease?
The symptoms of IBD can vary person to person and may change over time. It is common to experience periods of remission (during which little to no symptoms are present) and periods of flare-ups (during which symptoms are present).
Inflammation in the gut can cause symptoms such as:
- Frequent and urgent bowel movements
- Blood in stool
- Unintentional weight loss
- Abdominal pain and cramping
- Lack of appetite
How is Inflammatory Bowel Disease Treated?
Medications are usually chosen as first line therapy for IBD. These medications include 5-aminosalicylates, corticosteroids, immunomodulators, and biologics. The goals of therapy in IBD include mucosal healing, avoidance of complications, and improvement of quality of life. However, sustained remission (resolution of symptoms, during which the disease is no longer active) remains a therapeutic challenge. In addition, pharmacological IBD therapies often come with undesirable side effects.
Nutritional therapy has been investigated for its role in inducing remission in IBD, particularly in Crohn’s Disease. Recent research has shown that diet can impact many components of the IBD paradigm, including the intestinal microbiome, mucosal (gut lining) integrity, and the intestinal immune response.
Additionally, malnutrition is common in IBD due to disease activity, food restriction to manage symptoms, and poor intake. Therefore, nutritional interventions for IBD should focus on both correcting nutritional deficiencies and improving disease activity and symptoms.
Current Evidence Around Diet and IBD
The Western diet (a diet high in calories, meat, fat, sugar, processed foods, alcohol and food additives) has been hypothesized to play a role in disease processes and inflammation for many years. Research shows that diet influences the intestinal microbiome (our community of gut bacteria and other organisms) as well as mucosal integrity. For this reason, there is interest in using diet to treat the inflammation present in patients with IBD, particularly diets that can strategically target the gut microbiome.
Many diets have been reported to improve IBD in small case studies, including the specific carbohydrate diet (SCD), IBD anti-inflammatory diet (IBD-AID), and semi-vegetarian diet. However, there is not enough evidence to show that one diet is better than another.
Overall, a diet rich in fruits, vegetables, fibre and omega-3 polyunsaturated fatty acids, and lower in refined carbohydrates, omega-6 polyunsaturated fatty acids, animal products (particularly red and processed meats) and food additives may reduce the risk of developing IBD. Fibre in particular can help to protect and strengthen the mucosal lining of our gut. Our gut microbes feed on fibre and then produce short-chain fatty acids – which play a role in maintaining the integrity of our gut lining and producing mucous that may help protect against inflammation.
In addition to studies regarding the best dietary patterns for preventing IBD, studies have also investigated whether exclusive enteral nutrition (EEN) or partial enteral nutrition (PEN) plus the Crohn’s disease exclusion diet are effective at inducing remission for patients with IBD.
Enteral Nutrition and Inflammatory Bowel Disease
What is Enteral Nutrition?
Enteral nutrition (EN) is a nutritionally complete formula-based diet that contains macro- and micro-nutrients in a powder or liquid form. Exclusive enteral nutrition (EEN) provides 100% of daily nutritional requirements from a liquid nutrition formula. Typically in IBD, we have patients drink the formula orally as there is no barrier to swallowing. Usually when people think of enteral nutrition, they think of ‘tube feeds’ through a nose tube or tube in the stomach. When we talk about enteral nutrition in IBD, we are usually referring to oral intake of the formula. When 35-50% of regular food intake is replaced with enteral nutrition, it is known as Partial Enteral Nutrition (PEN).
EN is a low-risk, non-invasive therapy. In fact, it is recommended as first line therapy in pediatric Crohn’s disease, showing remission rates of up to 80%. However, it is not routinely used in adult populations in Western countries, primarily due to poor adherence due to poor tasting EN formulations.
Types of Enteral Nutrition Formula
EN formulations used in Canada vary. They include:
- Polymeric formulas – Polymeric EN contains whole proteins from sources such as milk, meat, egg or soy. They tend to be more palatable than other types of EN and are therefore commonly used.
- Semi-elemental formulas – Semi-elemental formulas contain shorter proteins which are less likely to activate an immune response. They are used in severe cases of Crohn’s disease in which malabsorption may occur.
- Elemental formulas – Elemental EN is amino acid-based and is used in cases of severe malabsorption, in cases where there may be impairment of the gastrointestinal tract, or if a person has a milk protein allergy.
A recent review demonstrated that there was no difference in remission rates or side effects between polymeric, semi-elemental and elemental EN formulas.
Mechanisms of Action in Crohn’s Disease
The exact mechanisms of action of exclusive enteral nutrition in the management of Crohn’s disease are unknown; however, it is thought that the following may be involved:
Immune system modulation
– EEN has been found to suppress or limit factors involved in the inflammatory response
– EEN may also have a direct anti-inflammatory effect
Alteration of the gut microbiome
– An important feature of Crohn’s disease is dysbiosis, or an imbalance in the composition of the gut microbiota. It is unclear whether this is a cause or a result of Crohn’s disease. Significant changes in microbiota composition have been shown to occur in Crohn’s disease after treatment with EEN.
Decreased permeability of the gut barrier
– EEN may reduce intestinal permeability and improve the regulation of what substances “get into” the gut. This prevents adherence of invasive bacteria, thereby reducing activation of an immune response.
– Drinking liquid formulas alters gut motility and allows the gut to rest
Improvement of overall nutritional status and nutrient delivery
– Many people struggle to get enough nutrition from food, particularly when symptoms are severe. Switching to EEN can ensure they are getting an appropriate amount and balance of nutrients
Overall, although the exact mechanisms of action of exclusive enteral nutrition for IBD are unclear, it is a promising dietary therapy for people with Crohn’s disease.
Who is Enteral Nutrition for?
Currently available therapies such as immunosuppressants, biologics and corticosteroids are not effective at treating IBD for all patients. Pharmacological treatments are also associated with many undesirable side effects, such as drug hypersensitivity, fever, rash, worsening of diarrhea, nausea, vomiting and abdominal pain. This can lead to a desire to pursue other treatment options which have fewer undesirable side effects.
EEN is the most rigorously studied dietary intervention in Crohn’s disease; however, it remains to be seen whether EEN or PEN are effective treatment strategies for ulcerative colitis. Therefore, we will mainly focus on nutrition therapy for Crohn’s disease in this article.
EEN or PEN may be beneficial for:
- Patients with active disease trying to induce remission
- Patients trying to maintain remission
- Patients failing biologic therapies
- Patients who are motivated and open to trying a more restrictive diet to induce or maintain remission
- Patients looking to avoid starting biologics
- Patients looking to avoid increasing their medication dosages
- Possible improvement of nutrition status to avoid surgery or improve nutrition status pre-operatively
Evidence-Based Ways to Utilize Enteral Nutrition for Crohn’s Disease
Exclusive Enteral Nutrition
EEN involves administering a complete liquid diet of enteral nutrition formula for 4 to 12 weeks, either orally or through a feeding tube. It has been shown to be as effective at inducing remission and mucosal healing as traditional corticosteroid therapy in pediatric studies, with up to 80% of Crohn’s disease patients achieving remission with EEN alone.
However, studies have shown that adults tend to struggle more with compliance to EEN and studies of its efficacy in adult populations have been less conclusive. Despite an interest in nutrition-based therapies for Crohn’s disease, EEN remains under-utilized and is not usually recommended by gastroenterologists as the first-line therapy for Crohn’s disease in adults in Canada. However, it is standard practice to recommend EEN as a first-line therapy for adults with Crohn’s disease in some other countries. With emerging evidence, we may start to see it used more often as a treatment option for inducing remission here in Canada as well.
EEN is not currently recommended as a primary therapy to maintain remission once a person achieves it, primarily due to the difficulties associated with maintaining such a restrictive diet.
Crohn’s Disease Exclusion Diet + Partial Enteral Nutrition
Partial enteral nutrition (PEN) is the use of an enteral formula in combination with a normal diet of solid foods. PEN has also been trialled to induce and maintain remission of Crohn’s disease. It is easier to tolerate than exclusive enteral nutrition (EEN) because some food is still allowed to be consumed. Unfortunately, while PEN has been shown to help maintain remission for longer than a regular diet, it has not been as effective as EEN in initially inducing remission in Crohn’s disease. However, while EEN has been shown to effectively induce and maintain remission, adherence to the diet is low and it is difficult to maintain long term. Therefore, experts have come up with a third option that lands somewhere in the middle between EEN & PEN.
The Crohn’s Disease Exclusion Diet + Partial Enteral Nutrition (CDED + PEN) aims to solve both the problem of adherence and the issues associated with remission and a normal diet. It combines PEN with an elimination diet that excludes dietary components that have been found to impair immunity, increase intestinal permeability, cause dysbiosis of the gut microbiota, or allow bacteria to penetrate the epithelial layer in animal studies. 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 re-induce remission in patients who are failing with biologic therapies.
CDED + PEN is a regimen comprising of three stages:
- Stage 1 (6 weeks): CDED + 50% of energy requirements from PEN
- Stage 2 (6 weeks): CDED + 25% of energy requirements from PEN
- Stage 3 (ongoing): Maintenance diet + 25% of energy requirements from PEN
While early studies of CDED + PEN show promising results for both the induction and maintenance of remission for patients with Crohn’s disease, it is important to note that most studies to date have studied the effectiveness of CDED + PEN in children. It remains to be seen whether the same levels of remission can be obtained in adult populations.
In addition, research has not yet been done to determine whether CDED + PEN would be an effective treatment for ulcerative colitis. Finally, the components excluded from the diet in CDED have been determined based on animal studies. Further studies in humans are required to determine whether these food components have the same negative effects in the human gastrointestinal tract.
Interested in trying EEN or PEN? We’re here to help!
If you’re living with IBD and are interested in trialling EEN or PEN to help induce or maintain remission, the team at Ignite Nutrition is here to help! It’s important to work closely with your family doctor and gastroenterologist to ensure that signs of remission are being monitored closely. Our dietitians can help you implement EEN or PEN and get you on the road to achieving remission of your IBD – work with one of our dietitians today!