Crohn's Disease

December 2021

Background

Crohn’s disease (CD) is a chronic inflammatory disorder that affects various sections of the gastrointestinal (GI) tract. It is believed to be caused by an interaction between genetic and environmental influences. However, there is no known etiology for the disease. Crohn's is characterized by an imbalance of pro and anti-inflammatory signaling in parts of the digestive tract. This leads to an alteration of the microbiome as well as a breakdown in intestinal barrier function. Often it appears that there is an imbalance in the species of bacteria that promote digestion and those that oppose digestion of some nutrients. Additionally, it has been found that up to one third of patients present complicated behavior such as strictures, fistulas, or abscesses. Many of these complications require 50% of patients to seek surgery within 10 years of diagnosis. Other symptoms include frequent diarrhea, abdominal pain/tenderness, intermittent vomiting, and weight loss. These symptoms range from mild to severe and can change over time depending on which area of the GI tract is inflamed.

The age of onset varies widely. The disease can be diagnosed at nearly every stage of life from 1 month old infants to people belonging to the oldest-old age group. A diagnosis requires x-rays of the GI tract, abdominal CT scans, and laboratory tests. X-rays and CT scans can reveal obstructions, abscesses, or fistulas of the abdomen. Other advanced imaging techniques can be utilized to gain a better understanding of the disease. Laboratory tests that screen for anemia, hypoalbuminemia, liver functionality, and electrolyte abnormalities should be considered. Fecal calprotectin is another marker of gastrointestinal inflammation which can be associated with remission if levels are less than 100mcg/g.

Crohn’s disease was once limited to North America and Europe but is now rising in developing countries. A 2013 review paper found high incidence rates in North America, northern Europe, and various parts of Asia as well as much of the developing world. For example, in France the rate of CD in pediatric groups increased 71% between 1998 and 2007. This rise in cases correlates with a shift towards a “western” lifestyle. A western diet is characterized by high amounts of total fat consumption, especially saturated fats from animals, milk, corn, and soybean oil. There is also a greater ratio of omega 6 fatty acids than omega 3 fatty acids associated with a “western” diet. Other aspects of a “western” lifestyle include improved sanitation and increased antibiotic usage.

Nutrition Therapy

There is no standard nutrition therapy for Crohn’s disease. Treatment options rely on individual needs of patients as each case varies in severity. Nutrition therapy methods generally consist of exclusion diets in which certain foods are limited or completely eliminated from the patient’s diet or alternative feeding methods such as parenteral and enteral nutrition. The European Society for Pediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines state the importance of evaluating nutritional balances on an individual basis prior to implementing food restrictions in order to avoid exacerbating symptoms.

A 12 week prospective study of children aged 4-18 years old with mild to moderate CD was conducted to compare the effectiveness of exclusive enteral nutrition and partial enteral nutrition therapy. The group given partial enteral nutrition experienced a decrease in gut bacteria associated with CD. Calprotectin levels dropped significantly for both groups at week 6 and continued to decline in the partial enteral nutrition group. Overall, the partial diet group sustained remission in a greater number than those in the exclusive enteral nutrition group.

Despite the effectiveness of enteral nutrition and its ability to promote gut healing, there are limitations to parenteral and enteral nutrition therapy such as low adherence levels and revulsion to formulas. In order to combat this, a 2019 study was carried out in patients with active Crohn’s disease to test for a novel dietary treatment for CD. The CD-TREAT diet recreates EEN by excluding certain dietary components such as gluten, lactose, and alcohol. The diet also matches macronutrient, vitamin, mineral, and fiber content of Modulen IBD which is the most popular formula in Europe. In addition to making substitutions for real food high in starch and low in fiber, this study favored protein sources over complex carbohydrates. It is important to note that micronutrient levels were achieved with a multivitamin. Researchers found that healthy adults complied with CD-TREAT easier and more than EEN. The ordinary food diet also induced similar effects to EEN on fecal microbiome, metabolome, and mean total sulfide.

Other diets such as the Mediterranean diet are being researched as treatment options for CD patients. One study found that the implementation of a Mediterranean diet in pediatric patients seems to correlate to a decrease in intestinal inflammation. This type of diet is high in vegetables, fruits, legumes, nuts, beans, cereals, grains, and low intake of meat and dairy products.

The following discussion will look at a review article that details the various alternative diets that can be used to treat Crohn’s disease. A low residue diet avoids all cruciferous vegetables, fruit peels, nuts, seeds, etc. Essentially all foods that metabolically ferment in the colon and decrease the movement of food along the digestive tract. This diet is quite restrictive and is only recommended for patients with bowel strictures or severe inflammation. Low residue diets may also lead to folate, vitamin A, vitamin C, and potassium deficiencies due to their restrictive nature. A potential complication of CD is the increased rate of lactose malabsorption. A lactose free diet would be a likely nutrition therapy option for these patients. However, when certain food products such as dairy are eliminated, there is a risk of developing vitamin D and calcium deficiencies. Cottage cheese, butter, or aged cheese are alternative options for CD patients that are lactose intolerant. Nutritional deficiencies should be monitored by checking vitamin D and B12 levels every 1 to 2 years as well as all other vitamins and minerals when deficiencies are suspected.

The next group of diets are those that restrict carbohydrates. A specific carbohydrate restricted diet eliminates all complex sugars, starches, grains, and legumes. Patients utilizing this diet will consume monosaccharides such as glucose or fructose found only in certain fruits, honey, and homemade yogurt. It also requires an extreme “introductory diet” which consists of homemade yogurt, gelatin, apple cider, chicken broth, and eggs followed by a slow introduction of cooked fruits and vegetables. This particular example is poorly studied in objective trials making it a less than desirable nutrition therapy option for CD. Avoiding certain fruits and vegetables is also a concern for achieving vitamin C, vitamin A, and potassium intakes especially in children and adolescents. Strict low carbohydrate diets lead to insufficient caloric intake and weight loss that will negatively impact the course of CD and exacerbate symptoms. Gluten has become a source of fear and concern for many across the globe. There is evidence showing the role of gluten in the direct activation of the innate immune system and decreasing intestinal barrier function. Seeing as CD is an inflammatory disorder of the digestive tract, a gluten-free diet can present itself as beneficial in some CD cases especially those with an iron deficiency or medically refractory disease.

Fat is another polarizing topic of discussion. Research shows that an emphasis on omega 3 fatty acids is recommended as they can regulate inflammation. Omega 6 fatty acids, on the other hand, are considered proinflammatory and may aggravate CD symptoms. Dietary sources such as flax seeds/oil, fish, oysters, and walnuts should be incorporated in CD patient diets. The bottom line is that there is no evidence that fat restricted diets alleviate symptoms or promote remission in CD patients.

Finally, enteral nutrition is the most restrictive yet likely the most effective diet in achieving remission. There are three types of enteral formulas: polymeric, semi-elemental, and fat/elemental. Each one contains a different concentration of one or more of the three macronutrients to meet various dietary needs. Some formulas contain simpler forms of macronutrients that are easier to absorb and digest than others. As previously mentioned, enteral formulas tend to lead to taste revulsion and social inconvenience making them difficult to introduce into a patient’s diet. There is a risk of insufficient caloric intake in patients that refuse to consume the formula or are not utilizing tube feeding.

To conclude, there are several overarching themes throughout the above nutrition therapy methods. First, careful carbohydrate selection appears to benefit overall gut function and reduce inflammation of the intestinal tract. Second, overly processed foods have become staples especially in urbanized communities and Western societies. Each diet emphasizes nutrient dense foods in favor of processed foods. This fact ensures that CD patients are meeting their daily macronutrient and micronutrients requirements from foods that will not exacerbate CD symptoms. Crohn’s disease impairs the intestinal barrier function and so introducing supplements such as multivitamins into a patient’s diet is beneficial in correcting or preventing nutrient deficiencies. Lastly, it should be noted that there is no single solution or therapy recognized among professionals in the treatment of Crohn’s disease. Each case is highly variable which means one therapy may work for one patient but not another.

Other Therapies

Corticosteroids, immunomodulatory treatments, biologic agents, and surgery are all recognized methods of treatment. Each one will vary in potency making treatments widely available to patients that suffer from mild to severe Crohn’s disease. Furthermore, physicians will consider disease location, disease activity and severity, previous response to therapy, individual risk factors for complications, and the cost and benefit/risk ratio of each drug. Medicinal treatments are not implemented with the hope of curing Crohn’s disease but instead aim to gain control of the disease and accompanying inflammation.

Other Lifestyle Restrictions

Disease management requires commitment and diligence from patients to identify lifestyle factors that lead to flares or pronounced symptoms that are short term or occur over an extended period of time. It is suggested that CD patients quit smoking as there is a correlation between smoking and the development of Crohn’s disease. Stress is another silent factor that strongly impacts symptoms of CD. Patients are advised to develop stress reduction techniques such as meditation or exercise to manage flares. Certain foods may need to be avoided if they worsen symptoms. Some will eliminate dairy, avoid greasy food, limit high fiber sources, and avoid foods that cause gas. Food journals and slowing down during meal time are useful tools in identifying causes of CD flares.

References

1. Crohn disease - gastrointestinal disorders. Merck Manuals Professional Edition. Accessed December 3, 2021. https://www.merckmanuals.com/professional/gastrointestinal-disorders/inflammatory-bowel-disease-ibd/crohn-disease

2. Torres J, Bonovas S, Doherty G, et al. Ecco guidelines on therapeutics in crohn’s disease: medical treatment. J Crohns Colitis. 2020;14(1):4-22. doi:10.1093/ecco-jcc/jjz180

3. Johnston RD, Logan RFA. What is the peak age for onset of IBD?: Inflammatory Bowel Diseases. 2008;14:S4-S5. doi:10.1002/ibd.20545

4. Strisciuglio C, Cenni S, Serra MR, et al. Effectiveness of mediterranean diet’s adherence in children with inflammatory bowel diseases. Nutrients. 2020;12(10):3206. doi:10.3390/nu12103206

5. Ng SC, Bernstein CN, Vatn MH, et al. Geographical variability and environmental risk factors in inflammatory bowel disease. Gut. 2013;62(4):630-649. doi:10.1136/gutjnl-2012-303661

6. Hwang C, Ross V, Mahadevan U. Popular exclusionary diets for inflammatory bowel disease: the search for a dietary culprit. Inflamm Bowel Dis. 2014;20(4):732-741. doi:10.1097/01.MIB.0000438427.48726.b0

7. Levine A, Koletzko S, Turner D, et al. ESPGHAN revised porto criteria for the diagnosis of inflammatory bowel disease in children and adolescents. J Pediatr Gastroenterol Nutr. 2014;58(6):795-806. doi:10.1097/MPG.0000000000000239

8. Levine A, Wine E, Assa A, et al. Crohn’s disease exclusion diet plus partial enteral nutrition induces sustained remission in a randomized controlled trial. Gastroenterology. 2019;157(2):440-450.e8. doi:10.1053/j.gastro.2019.04.021

9. Svolos V, Hansen R, Nichols B, et al. Treatment of active crohn’s disease with an ordinary food-based diet that replicates exclusive enteral nutrition. Gastroenterology. 2019;156(5):1354-1367.e6. doi:10.1053/j.gastro.2018.12.002

10. MD JG. Living with Crohn’s disease: Recognizing and managing flares. Harvard Health. Published November 26, 2019. Accessed December 3, 2021. https://www.health.harvard.edu/blog/living-with-crohns-disease-recognizing-and-managing-flares-2019112618410