Dietary Interventions Can Support IBD Treatment

Carolyn Crist

December 21, 2022

Some solid food diets may aid in the treatment of inflammatory bowel disease (IBD), though the overall quality of evidence remains low and additional data is needed, according to a new report.

For Crohn's disease, a diet low in refined carbohydrates and a symptoms-guided diet appeared to help with remission, yet reduction of refined carbohydrates or red meat didn't reduce the risk of relapse. For ulcerative colitis, solid food diets were similar to control measures.

Dr Berkeley Limketkai

"The internet has a dizzying array of diet variants touted to benefit inflammation and IBD, which has led to much confusion among patients, and even clinicians, over what is truly effective or not," Berkeley Limketkai, MD, PhD, director of clinical research at the Center for Inflammatory Bowel Disease at the University of California at Los Angeles, told Medscape Medical News.

"Even experiences shared by well-meaning individuals might not be generalizable to others," he said. "The lack of clarity on what is or is not effective motivated us to perform this systematic review and meta-analysis."

The study was published online in Clinical Gastroenterology and Hepatology.

Analyzing Diets

Some nutritional therapies, such as exclusive enteral nutrition, have good evidence to support their use in the treatment of IBD, Limketkai said. However, patients often find maintaining a liquid diet difficult, particularly over a long period of time, so clinicians and patients have been interested in solid food diets as a treatment for IBD.

In 2019, Limketkai and colleagues conducted a systematic review and meta-analysis of randomized controlled trials focused on solid food diets for IBD that was published with the Cochrane Collaboration. At that time, the data were considered sparse, and the certainty of evidence was very low or low. Since then, several high-quality trials have been published.

For this study, Limketkai and colleagues conducted an updated review of 36 studies and a meta-analysis of 27 studies that compared a solid food diet with a control diet in patients with Crohn's disease or ulcerative colitis. The intervention arm had to involve a well-defined diet, not merely a "usual" diet.

Among the studies, 12 evaluated dietary interventions for inducing clinical remission in patients with active Crohn's disease, and 639 patients were involved. Overall, a low refined-carbohydrate diet was superior to a high-carbohydrate diet or a low-fiber diet. In addition, a symptoms-guided diet, which sequentially eliminated foods that aggravated a patient's symptoms, was superior to conventional nutrition advice. However, the studies had serious imprecisions and very low certainty of evidence.

Compared with respective controls, a highly restrictive organic diet, a low-microparticle diet, and a low-calcium diet were ineffective at inducing remission of Crohn's disease. Studies focused on immunoglobulin G-based measures were also inconsistent.

When comparing diets touted to benefit patients with Crohn's disease, the Specific Carbohydrate Diet was similar to the Mediterranean diet and the whole food diet, though the certainty of evidence was low. Partial enteral nutrition was similar to exclusive enteral nutrition, though there was substantial statistical heterogeneity between studies and very low certainty of evidence.

For maintenance of Crohn's disease remission, researchers evaluated 14 studies that included 1211 patients with inactive disease. Partial enteral nutrition appeared to reduce the risk of relapse, although evidence certainty was very low. In contrast, reducing red meat or refined carbohydrates did not lower the risk of relapse.

"These findings seemingly contradict our belief that red meat and refined carbohydrates have pro-inflammatory effects, although there are other studies that appear to show inconsistent, weak, or no association between consumption of unprocessed red meat and disease," Limketkai said. "The caveat is that our findings are based on weak evidence, which may change as more studies are performed over time."

For induction of remission in ulcerative colitis, researchers evaluated three studies that included 124 participants with active disease. When compared with participants' usual diet, there was no benefit from a diet that excluded symptom-provoking foods, fried foods, refined carbohydrates, additives, preservatives, most condiments, spices, and beverages other than boiled water. Other studies found no benefit from eliminating cow milk protein or gluten.

For maintenance of ulcerative colitis remission, they looked at four studies that included 101 patients with inactive disease. Overall, there was no benefit from a carrageenan-free diet, anti-inflammatory diet, or cow milk protein elimination diet.

Helping Patients

Although the certainty of evidence remains very low or low for most dietary trials in IBD, the emerging data suggest that nutrition plays an important role in IBD management and should be considered in the overall treatment plan for patients, the study authors wrote.

Dr James Lewis

"Patients continue to look for ways to control their IBD, particularly with diet. Providers continue to struggle with making evidence-based recommendations about dietary interventions for IBD. This systematic review is a useful tool for providers to advise their patients," James Lewis, MD, associate director of the Inflammatory Bowel Diseases Program at the University of Pennsylvania, Philadelphia, told Medscape Medical News.

Lewis, who wasn't involved with this study, has researched dietary interventions for IBD. He and colleagues have found that reducing red meat does not lower the rate of Crohn's disease flares and that the Mediterranean diet and Specific Carbohydrate Diet appear to be similar for inducing clinical remission.

Based on this review, partial enteral nutrition could be an option for patients with Crohn's disease, Lewis said.

"Partial enteral nutrition is much easier than exclusive enteral nutrition for patients," he said. "However, there remains uncertainty as to whether the solid food component of a partial enteral nutrition approach impacts outcomes."

As more dietary studies become available, the certainty of evidence could improve and lead to better recommendations for patients, Limketkai and colleagues wrote. They are conducting several studies focused on the concept of precision nutrition.

"While certain diets may be helpful and effective for IBD, different diets work differently in different people. This concept is no different than the fact that different IBD medications work differently in different individuals," Limketkai said. "However, given the current state of evidence for dietary interventions in IBD, we still have a long path of research ahead of us."

The study received no funding. The study authors reported no conflicts of interest. Lewis reported no relevant disclosures.

CGH. Published online December 2, 2022. Full text.

Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape, MDedge, and WebMD.

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