Diet and the impact of nutrition for managing inflammatory bowel disease (IBD), Crohn’s disease and ulcerative colitis, has gained considerable attention from researchers and patients in recent years. Though it is one component—albeit a complex one—of an already complicated disease process, it is a modifiable feature and an exciting target, experts say.

“We can’t change our genetics,” says Sandra Kim, MD, Chief of Pediatric Gastroenterology at Cleveland Clinic Children’s.

“However, diet may impact the risk of developing certain types of inflammatory bowel diseases. Furthermore, given that specific defined diets can be utilized as part of treatment for some patients living with IBD, there has been a strong interest among patients and providers in understanding better what is available to them to make data-driven decisions,” she says.

Impaired gut function

How exactly does diet impact the GI tract? Diets like the Mediterranean diet, which are less processed with fewer additives like emulsifiers and rich in fruits and vegetables, whole grains, and seafood, can help promote greater diversity within the gastrointestinal tract. Furthermore, this may impact the balance of pro- and anti-inflammatory microbes.

By contrast, Western diets, high in red meat, processed food, refined sugar, and saturated fats, can lead to dysbiosis, or a lack of diversity, within the gut microbiome. Evidence shows this can lead to impaired barrier function and dysregulation of immune-regulating cells, making individuals with IBD more susceptible to inflammation in the intestine.

A closer look at recent data

There have been ongoing investigations into the overall impact of diet in pediatric patients with IBD, especially those with Crohn’s disease, in the last several years. This reflects a growing interest in diet, its link to inflammation, and, subsequently, disease exacerbation—as well as its role as therapy.

Benefits and challenges of formula-based therapies

Exclusive enteral nutrition (EEN) is the original nutrition-based intervention for managing patients living with mild-to-moderate Crohn’s disease. Formula constitutes most of the calories consumed as either primary or adjunctive therapy, typically for eight to 12 weeks. This approach has been utilized in Europe and Canada for decades with increased utilization in the United States over the past decade.

Dr. Kim explains that EEN can be highly effective as an induction therapy, the first phase of therapy to quiet down inflammation, without the side effects associated with medications like steroids.

She adds, “It can be effective in patients who cannot tolerate solid foods due to complications related to their Crohn’s disease, like strictures in the small intestine, as optimization prior to upcoming IBD-related surgeries, or for effective nutritional repletion in patients who are malnourished due to their IBD.”

However, there are also challenges associated with utilizing EEN. Despite being recognized as an effective therapy for some patients with Crohn’s disease, insurance will often not cover this. Furthermore, there are issues with palatability. “For some patients, drinking by mouth may be easier, while delivery by nasogastric tube is a better option for others,” notes Dr. Kim.

Finally, as studies have shown, patients—even those who had prior success with EEN—would prefer a specific defined diet over EEN if possible.

Research efforts to upend challenges are underway

Whole food blended smoothie. Promising results from a small pilot trial show that a whole food blended smoothie, created with micro and macro nutrients from polymeric formula, may provide similar clinical benefit to those of commercial EEN formulas. Study participants, pediatric patients with a new mild-to-moderate Crohn’s disease diagnosis, experienced decreased fecal calprotectin (a stool marker for inflammation) and clinical remission.

CD-TREAT. Another trial demonstrated that CD-TREAT, an individualized food-based diet, may offer an alternative to EEN by replicating the formula’s nutritional components but using ordinary food. Results suggest that it indeed mirrors many aspects of EEN while also offering a potentially more accessible and desirable alternative.

The Crohn’s disease exclusion diet (CDED). In addition to diets replicating EEN, recent studies have investigated the feasibility of specific defined diets, which consist of certain food items with a focus on limiting or eliminating processed foods and additives. CDED combines both elements, a whole food diet with partial enteral nutrition, to minimize exposure to potential inflammation-inducing components, as therapy for some patients with Crohn’s disease. Initial studies have shown that CDED was effective in both clinical remission and decreases in inflammatory markers.

Latest information on older diets

Recent studies have also compared the Mediterranean diet to the specific carbohydrate diet (SCD). The latter, popularized in the 1920s, is a diet composed of specific food items (grain-free, low sugar, and low lactose) with whole non-processed ingredients.

Despite a demonstrated clinical benefit, recent studies have shown it may provide limited mucosal healing. In a one-to-one study, SCD only marginally edged out the Mediterranean diet, although SCD is more limited in options and may be more challenging to implement and sustain.

The next frontier: Precision nutrition, implementation and monitoring, and biomarkers

While new data points on defined diets for IBD are encouraging, Dr. Kim emphasizes that both diets and people are complex and stresses, “we need better evidence of specific components within the diet that perpetuate inflammation versus those that play a protective role, a concept known as precision nutrition.”

She also calls attention to the need for effective implementation and monitoring when patients are started on a nutritional therapy for their IBD. Part of this, she says, requires close collaboration with dietitians who play a critical role in therapy implementation, nutritional monitoring, and patient education.

Finally, better biomarkers are needed to help predict the impact of these components on disease.

“This is especially critical considering the significant impact IBD has on our patients’ quality of life. If we are going to ask them to utilize nutritional therapies, recognizing how tough it can be, we need to make sure we are making informed decisions. Our patients deserve no less than this.”