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Dietary interventions may help in the overall management of inflammatory bowel disease (IBD), but caution is required when interpreting the available data on this, according to Peter Gibson, MD, of Monash University in Melbourne, Australia.

"This is a very exciting area because there has been a profusion of recent publications on diet and IBD," he said at the Advances in Inflammatory Bowel Diseases virtual meeting.

An important question that researchers have been exploring is whether diet can be used to influence disease activity and lessen inflammation. "The use of exclusive enteral nutrition has told us that this is very much the case -- you can reduce inflammation and induce mucosal healing with exclusive enteral nutrition," he said. "But can it be done with real food?" he asked.

This question was addressed in that compared exclusive enteral nutrition with the Crohn's Disease Exclusion Diet, which is intended to exclude dietary components that can cause dysbiosis, alter innate immunity, and affect barrier function. The diet requires increases in fruit and vegetable consumption, high quality lean protein, complex carbohydrates, healthy oils, and fiber, along with decreases in animal and saturated fats, wheat, dairy, emulsifiers, maltodextrin, and sulfites.

The study included 74 patients whose mean age was 14 years. They were randomly assigned to one of two diets: One group received the Crohn's exclusion diet plus 50% of calories from enteral formula for 6 weeks followed by the exclusion diet plus 25% partial enteral nutrition through week 12. The other group were given exclusive enteral nutrition for 6 weeks and then a free diet with 25% partial enteral nutrition through week 12.

Compliance and clinical response were similar in the two groups but tolerance was superior for the exclusion diet (97.5% vs 73.6%, OR 13.92, 95% CI 1.68-115.14, P=0.002). Improvements were observed not only for symptoms but also for markers of inflammation such as C-reactive protein and fecal calprotectin.

"But it's a complicated, dietitian-delivered diet, and is not suitable as a maintenance diet. It can be recommended if only to improve tolerance to enteral nutrition," Gibson noted.

The Mediterranean diet also has demonstrated benefits in many disease states, including IBD. In from Greece of patients with Crohn's disease, adherence to the Mediterranean diet was associated with improved quality of life and lower disease activity, while in a from Italy, the Mediterranean diet correlated with decreased intestinal inflammation.

Dietary interventions also can help with functional gut symptoms that are not directly related to inflammation, Gibson said. Up to 30% of patients with quiescent IBD can have chronic functional symptoms, and studies have shown that a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) can help with this problem.

In that included 52 patients with quiescent Crohn's disease or ulcerative colitis, 52% of patients given the low FODMAP diet reported relief of their gut symptoms after 4 weeks compared with 16% of those following a sham diet (P=0.007).

"But I would like to stress that dietary manipulation is a risky therapy in IBD, because malnutrition in IBD is already high, and if you are going to use a restrictive diet you really should work with a dietitian skilled in IBD management to ensure that you're not exacerbating these issues," he cautioned.

A further area of research into diet and IBD has been on whether preventive dietary measures could help long-term or even for the offspring of people at risk. This topic, however, has presented difficulties in study interpretation, with inconsistencies in how food frequencies are defined and measured. For instance, fiber may have long-term benefits, but in some studies the measured fiber was from cereal and in other studies the fiber was from fruit and vegetables.

However, from the Nurses' Health Studies did offer some insight into the long-term effects of a dietary pattern in which an Empirical Dietary Inflammatory Pattern score was calculated based on 18 foods weighted for potential inflammatory properties. Compared with individuals with the lowest inflammatory pattern scores, those with the highest scores had a 51% higher risk of having Crohn's disease. Moreover, over a period of 8 years, those who shifted from a low to high inflammatory score diet had a significantly increased risk of developing Crohn's disease (HR 2.05, 95% CI 1.10-3.79).

Questions arose from this study however, in that fish and tomatoes were weighted as being pro-inflammatory, while beer, pizza, and snacks were classified as being protective. "This was not a guide to healthy eating," he said, "but does provide evidence for the concept of the inflammatory diet pattern," he emphasized.

Interpret the study with caution, he said, as it also contains a generous portion of bias. "If this were all true, we would be recommending lots of pizza and snacks to our patients and clearly this is not the case. What the authors of this and other studies have said is that people shouldn't eat too much red meat and so forth, but they are cherry-picking the things that fit in with their biases."

"Nonetheless, this is really exciting stuff and is going to hopefully lead to preventive strategies," Gibson concluded.

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