When many patients think about a Crohn’s disease diet, they think of the foods they can’t eat, since so many foods are viewed as triggers that can initiate or exacerbate painful and debilitating gastrointestinal symptoms. While it is true that some elimination diets are supported by strong preliminary evidence, it is important to recognize that there are also studies indicating that certain foods are particularly good for Crohn’s disease patients. When it comes to the management of Crohn’s disease, focusing on positive action—that is, emphasizing an increase in the intake of foods that patients can eat rather than limitations on the foods they should avoid—can be a more empowering approach for patients who have struggled with seemingly intractable gastrointestinal symptoms for years. The latest research suggests that some of the best foods for Crohn’s disease include those that are high in fiber and those that combine probiotics with prebiotic fiber. In addition, there are dietary supplements that can build on the nutritional benefits of these foods that make an even bigger impact on distressing symptomatology.
High-Fiber Foods for Crohn’s Disease? Taking a Second Look
For patients with Crohn’s disease, the advice to eat more fiber may come as a bit of a surprise. After all, physicians have been recommending low-fiber diets for Crohn’s disease patients for decades based on the assumption that fiber could potentially trigger and intensify symptoms. However, the body of research suggesting the potential benefits of high-fiber diets has a long history and is gaining traction within the scientific and clinical communities.
As early as the mid-1970’s, there has been clinical evidence that fiber does not actually harm patients. For instance, in one randomized control study of seventy Italian patients with Crohn’s disease from 1985, researchers found that switching patients from a low-fiber diet to a standard Italian diet had no negative effect on gastrointestinal symptoms and did not lead to intestinal obstruction, as some clinicians at the time would have predicted. Rather, it allowed the patients to enjoy more appetizing meals, and it also increased the overall nutritional content of patients’ diets. Still, only recently have researchers begun to take the notion of the benefits of a high-fiber diet more seriously. The impetus for the research came partly from observations that the incidence and severity of Crohn’s disease were on the rise in Western nations where processed foods were replacing high-fiber whole grains.
In order to explore the connection between dietary fiber and Crohn’s disease, a group of researchers at the University of Virginia conducted a randomized, controlled, single-blind clinical trial in which different groups of adult patients with Crohn’s disease received different instructions for dietary fiber intake. Specifically, the control group was told to follow the traditional advice given to Crohn’s disease patients: stay hydrated and avoid whole grains, dairy products, and high-fiber foods on days when symptoms are particularly prominent. In contrast, the patients in the intervention group were instructed to eat one packet of whole wheat bran cereal (which was provided by the study coordinator) and drink at least 48 ounces of unsweetened fluids each day. At the end of the four-week trial, the results were remarkable: not only did the patients in the wheat bran-inclusive diet experience no worse symptoms, but they actually reported significant improvements in both quality of life and gastrointestinal function. Moreover, there were no significant increases in biomarkers for inflammation, indicating that fiber intake does not promote the physiological processes that underpin Crohn’s disease.
One hypothesis that has been proposed to explain the benefits of a high-fiber diet for Crohn’s disease patients is the fact that indigestible fiber is metabolized to butyric acid by gut bacteria. This should come as no surprise since butyric acid is involved in a wide range of inflammation-related processes that may affect the pathophysiology of Crohn’s disease. Indeed, some studies have shown that populations of some of the gut bacteria that produce butyrate, such as Faecalibacterium prausnitzii, are lower in patients with Crohn’s disease. In a study in Japan in 2015, researchers conducted a small-scale, case-controlled trial in which a plant-based, semi-ovo-lacto vegetarian diet was initiated for patients with Crohn’s disease, with the goal of providing the limited population of butyric acid-producing bacteria with more dietary fiber to ferment. When patients started taking in an average of 32.4g of dietary fiber per day (within a 2000 calorie diet) alongside a biologic drug, they achieved a short-term decline in gastrointestinal symptoms, as well as a 92 percent remission rate after two years. These results suggest that high-fiber fruits and vegetables may be some of the best foods for patients with Crohn’s disease. They also indicate that directly introducing butyric acid as a nutritional supplement may also offer relief for Crohn’s disease patients by simulating an increase in butyric acid by key gut bacteria.
The Benefits of Fermented Foods and Prebiotic Fiber for Patients with Crohn’s Disease
Rigorous clinical evidence on the benefits of probiotics is still lacking, but there is still strong support for the notion that a diet supporting the health of the microbiome can improve symptoms in patients with Crohn’s disease. Some studies with supplementary probiotics have indicated that introducing certain types of bacteria can ameliorate symptoms. There are also studies that show that fecal transplantation that introduces new microbiota into a patient’s GI tract can have significant results. Therefore, researchers have yet to fully abandon the idea that probiotic-rich fermented foods—like yogurt, kombucha, bean paste, and miso—are among the best foods for Crohn’s disease.
Intriguingly, one of the principles of the Autoimmune Protocol Diet-—an increasingly popular dietary guideline for Crohn’s disease patients—is to combine foods that are high in prebiotic fiber with probiotics, and this approach has been shown to be more effective than supplementation with probiotics alone. In one study on the Autoimmune Protocol Diet, patients were encouraged to eat leek and onion (two foods high in prebiotic fiber) alongside fermented foods, and after four weeks, all of the patients in the study reported symptom improvement. While it is true that this study was extremely small—only 8 patients with Crohn’s disease took part—the combination of prebiotic fiber and probiotics may be a promising strategy for patients who have not had success with probiotic-only therapy in the past.
Additionally, the results supported an earlier study, which suggested that a therapeutic combination of a probiotic containing lactic acid bacteria and psyllium (a prebiotic fiber) induced remission in patients with active Crohn’s disease. Indeed, of the probiotic-containing foods and supplements that are supported by rigorous research, some of the most promising are those that contain lactic acid bacteria. Notably, lactic acid bacteria are known to produce butyric acid, the above-described multifunctional compound that is involved in a wide range of anti-inflammatory processes. This association suggests that the benefits of these foods, like those of the high-fiber foods, may be mediated through an increase in the production of butyric acid by gut bacteria.
Making Smart Dietary Changes: Options for Crohn’s Disease Patients
There are no definitive results on the best foods for Crohn’s disease patients, but the evidence indicates that the most promising dietary options are to choose foods and supplements that support the health of the gut microbiome. By increasing intake of cereal-, fruit- and vegetable-based dietary fiber, and by combining prebiotic fiber with probiotic foods, patients may experience short-term relief and maintain long-term remission. Supplements that directly introduce butyric acid, which is otherwise produced when gut bacteria metabolize dietary fiber, may also have similar effects, so patients and practitioners may want to consider including this emerging supplement in their treatment strategies.
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