Crohn’s disease is an inflammatory disease of the gastrointestinal tract. Several studies suggest that diet plays a vital role in the etiopathogenesis of Crohn’s disease. To learn more about the role diet plays in managing symptoms of Crohn’s disease, Medscape spoke with Berkeley N. Limketkai, MD, PhD, a gastroenterologist and director of clinical research at the UCLA Center for Inflammatory Bowel Diseases in Los Angeles, California, and Kelly Issokson, MS, RD, CNSC, a clinical dietitian at Cedars-Sinai in Los Angeles, California. Read on for their insights.
How does a specific dietary pattern influence the severity and frequency of Crohn’s disease (CD) flare-ups?
Berkeley N. Limketkai, MD, PhD: Diet can affect both symptoms and inflammation in CD, with research demonstrating the efficacy of certain forms of dietary intervention on active CD. Exclusive enteral nutrition (ie, the sole use of oral nutrition supplements for nutrition) has been shown to help induce remission in CD, leading some medical and nutrition societies to recommend it as a corticosteroid-sparing therapy for mild to moderate active CD. There are clinical trials also affirming the efficacy of solid food diets, such as the Mediterranean diet, specific carbohydrate diet, and Crohn’s disease exclusion diet, to induce remission in CD. Inversely, one could infer that in a state of remission, diet could help reduce the risk for and severity of flares.
In one of our earlier studies involving 691 participants with inflammatory bowel disease (IBD), 36% of whom had CD, we found that certain diet patterns were associated with a lower risk for symptom relapse compared with the “Western diet.” So, is it a specific diet or a specific dietary pattern that is helpful? I propose that it is more the latter. For one, diets with purported benefits for patients with CD contradict one another on which food groups are permissible and which are prohibited. Moreover, in one of our clinical trials at UCLA on dietary intervention for CD, we found that a higher Healthy Eating Index score might be the stronger driver of benefit. In other words, a healthy diet pattern — a common theme across the previously mentioned diets — may be more important than a specific “designer” diet itself.
Kelly Issokson, MS, RD, CNSC: We used to believe that fiber was not good for people with IBD, and for a long time many patients were advised to follow a low-fiber diet. What we are learning now is that fiber not only helps patients feel better but may also decrease the risk for flaring over time. A recent study, led by Dr James Lewis, showed that patients who had active CD felt better when they increased fiber in their diet. This study, along with other previous studies, supports a diet rich in fruits and vegetables for people with IBD.
Texture modifications can help with tolerance in patients with stricturing disease. For example, pureeing fruits and vegetables, choosing nut and seed butters instead of whole nuts, and choosing soft-cooked or mashed foods can be a good approach to modifying fiber texture for improved tolerance. The Crohn’s and Colitis Foundation launched a recipe website (GutFriendlyRecipes.org) that has hundreds of gut-friendly recipes, all vetted by registered dietitians. Users can also filter for specific diets (eg, Mediterranean diet), meal types (eg, breakfast, snack), and diet needs (eg, flare-friendly, stricture friendly).
How do different dietary patterns, such as low-FODMAP or elimination diets, affect symptoms and quality of life in patients with CD?
Limketkai: The low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet was designed primarily to treat irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth. In simplistic terms, its premise involved depriving gut microbes of an excess of undigested refined or simple carbohydrates. Although this mechanism can have an effect on low-grade inflammation that stems from an aberrant gut microbial composition, it does not necessarily address inflammation— a key driver of symptoms and reduced quality of life in patients with CD. On the other hand, given the common overlap between IBS and similar conditions with CD and the nonspecific improved sense of well-being reported by patients who moderate FODMAP consumption (similar to the effect individuals without celiac disease may also derive from gluten avoidance), there can be symptomatic improvement with FODMAP exclusion for patients with CD.
A caveat with the low-FODMAP diet and other elimination diets is the risk for malnutrition or micronutrient deficiencies from these narrow diets. Before starting on a low-FODMAP diet, I recommend that patients seek guidance from a registered dietitian to determine whether it is an appropriate intervention for them and to reduce the risk for malnutrition.
Issokson: Some people with CD may continue to have symptoms even though blood, endoscopy, or imaging tests show no [signs of] inflammation. In these instances, IBS could be driving their symptoms. If IBS is present, a dietitian can help patients identify diet modifications that may improve their symptoms. One approach is a low-FODMAP diet — a short-term elimination diet that focuses on reducing carbohydrates (oligosaccharides, disaccharides, monosaccharides, and polyols) that may worsen IBS symptoms. This diet is short-term and is not suitable for everyone, so patients are advised to consult a gastroenterologist and dietitian before starting this or any diet.
What role do specific vitamins and minerals, such as vitamin D and zinc, play in the management and progression of CD?
Limketkai: Prior epidemiologic studies have suggested that vitamin D deficiency may lead to the development or worsening of CD. However, our lab and others that measured longitudinal predisease vitamin D concentrations did not find an association with incident CD. We also performed a Cochrane review of vitamin D intervention trials in CD and found that there might be fewer clinical relapses among those who received a vitamin D supplement vs placebo; however, the certainty of evidence was low. There are not many data on the use of other vitamins and minerals as a treatment for CD.
In any case, vitamins and minerals are very important to consider in the management of CD owing to the high risk for micronutrient deficiency associated with the condition. For example, CD in the ileum can interfere with vitamin B12 absorption. Inflammation can lead to iron and vitamin D deficiency. Intestinal inflammation, particularly when higher in the gastrointestinal tract, can lead to nutrient malabsorption.
Issokson: Vitamin D levels are often insufficient in people with IBD. Evidence suggests that vitamin D plays a role in regulating the immune system, maintaining bone health, improving response to medications, decreasing risk for cancer, and improving other health and IBD-related outcomes.
Do probiotics and prebiotics affect inflammation and intestinal permeability in individuals with CD?
Limketkai: Probiotics and prebiotics, by definition, are food products that should confer a health benefit. Certain probiotics — based on the microbial composition — are effective in reducing inflammation in ulcerative colitis, but not in CD. On the other hand, I am not yet convinced the issue is a lack of efficacy but rather a lack of research. When we performed a Cochrane review of probiotics in CD, only two randomized trials had rigorously evaluated the role of probiotics for induction of remission in CD. More research is needed.
As for prebiotics, which are nondigestible carbohydrates used by gut bacteria to produce beneficial metabolites, the data are even more scarce. We performed a systematic review and meta-analysis that catalogs the randomized trials of different prebiotics for IBD. In short, although there are theoretical mechanistic benefits from probiotics and prebiotics for CD, the data are currently too sparse to make any conclusion — even a weak one).
Issokson: There is not enough evidence to show a significant benefit of supplemental prebiotics or probiotics for reducing inflammation in CD. Dietary sources of prebiotics and probiotics may improve GI symptoms, intestinal function, diet variety, nutritional balance, and gut microbiome diversity. Dietary sources of prebiotics and probiotics include cooked and cooled potatoes, beans, lentils, oats, bananas, garlic, onions, yogurt, kimchi, miso, tempeh, and natto.
Can dietary interventions influence the need for surgical intervention in patients with CD over time?
Limketkai: The need for surgical intervention in CD stems largely from persistent inflammation that leads to disease progression and disease-related complications. This phenomenon has motivated the medical community to focus more on early and assertive control of inflammation in CD. In some cases, this includes the initiation of powerful biologic therapies or even surgery soon after diagnosis. One would surmise that controlling inflammation with pharmacologic or nonpharmacologic therapy would reduce the risk for surgery. There is a growing body of evidence demonstrating this to be true with traditional pharmacologic therapy. The data are not yet available on diet therapy, but if inflammation is the pathway toward the need for surgical intervention, then dietary interventions that effectively control inflammation would reduce the downstream risk for surgery.
Diet monotherapy may not necessarily be effective for everyone in controlling inflammation. That does not mean that diet is not effective or important; it might just need to be utilized in combination with other strategies, such as traditional pharmacologic agents. In my clinical practice, the more optimal approach is to leverage diet either way, be it as a monotherapy (for the fortunate few who have the discipline to adhere to the diet and the biology to benefit from this strategy) or in combination with other therapies. The approach needs to be personalized.
Issokson: Some evidence suggests that patients who follow a partial enteral nutrition (PEN) diet, where about half [35%-50%] of calories come from a [liquid] nutrition formula and the other half come from a regular [food] diet, can stay in remission for longer periods of time. So, PEN may reduce the need for surgical intervention by maintaining flare-free periods. [Editor’s note: Please also see specialized enteral nutrition therapy: Review of Exclusive Enteral Therapy in Adult Crohn’s Disease.] Other evidence suggests that for patients who will need surgery, nutritional optimization may help to improve outcomes, including faster recovery and reduced risk for intra-abdominal inflammation.
Berkeley N. Limketkai, MD, PhD,has disclosed the following relevant financial relationships:
Serve(d) as an advisory board member for: Johnson & Johnson
Serve(d) on a speakers bureau for: Johnson & Johnson
Hold(s) equity in: Azora Therapeutics
Kelly Issokson, MS, RD, CNSC, has disclosed the following relevant financial relationships:
Serve(d) as a consultant for: Takeda Pharmaceuticals; Crohn’s and Colitis Foundation
