A constant concern of Crohn’s patients is how to regulate their diet, and we hope that this article will help you to better maintain Crohn’s disease in remission.
Crohn’s disease is an autoimmune intestinal disease of unknown etiology. The lesions are intermittently distributed in the intestine and can be involved from the oral cavity to the anus, but the terminal ileum and ileocecal area are most commonly involved. The etiology of Crohn’s disease involves genetic, immune and environmental factors, i.e. autoimmune abnormalities induced by external environmental factors in a susceptible population carrying risk genes. In addition to hygienic conditions, smoking and alcohol abuse, and antibiotic abuse, changes in dietary habits are thought to be an important reason for the increasing incidence of Crohn’s disease year by year. Food antigens and altered intestinal flora may be important mechanisms by which diet influences the development of intestinal inflammation. Whether there is indeed a correlation between dietary patterns and Crohn’s disease is still not fully conclusive. In the following, we will outline several aspects of the main clinical studies related to diet and Crohn’s disease and suggest dietary recommendations for Crohn’s disease patients in light of the available evidence.
I. Diet and risk of disease
1. Protein
Shoda found that the incidence of Crohn’s disease was positively correlated with the consumption of total protein, animal protein and milk protein, and that protein from vegetables was protective against the disease. Another large prospective study of middle-aged and older French women found that a high consumption of animal proteins such as meat and fish (rather than eggs and dairy products) may be associated with the development of Crohn’s disease in 67,581 middle-aged women followed up for an average of 10.4 years. Since the consumption of animal proteins is often accompanied by the consumption of animal fats, this conclusion needs to be further verified.
2. Sugars
Several studies have confirmed that high consumption of total carbohydrates, sucrose, mono- and disaccharides, and refined sugars may be associated with the development of Crohn’s disease. a 2013 Danish population-based study found that high sugar intake may be associated with the development of Crohn’s disease in childhood. Notably, Jantchou’s prospective study of a large sample did not find an association between carbohydrate consumption and the onset of Crohn’s disease.
3. Fat
Hou et al. 2011 conducted a systematic review of studies related to diet and the development of Crohn’s disease and found that high intakes of saturated fats, monounsaturated fatty acids, polyunsaturated fatty acids, Omega-3 fatty acids, Omega-6 fatty acids, and meat were reported to increase the risk of Crohn’s disease in the population, while dietary fiber and fruit reduced this risk. Two authoritative prospective surveys, however, did not reach similar conclusions. The French E3N study, which included 67,581 middle-aged women for follow-up, did not find an association between fat intake and the development of Crohn’s disease. In the US NHS study, which followed 170,000 women, 269 of whom subsequently developed Crohn’s disease, the authors found that saturated, unsaturated and polyunsaturated fatty acids did not increase the risk of Crohn’s disease after analyzing their dietary habits.
Two retrospective studies by Maconi and Amre found that eating fish may help prevent Crohn’s disease. However, the Jantchou study found that high fish consumption may increase the risk of Crohn’s disease. Therefore, it remains to be confirmed whether seafood products are associated with the development of Crohn’s disease.
4, dietary fiber, fruits and vegetables
Soluble dietary fiber can be fermented by intestinal flora after consumption, producing short-chain fatty acids. Short-chain fatty acids are metabolites with significant anti-inflammatory properties that can reduce the risk of Crohn’s disease in adults. Dietary fiber-rich whole wheat bread and oatmeal have been shown to have a protective effect on the intestinal tract, and Gilat et al. found that low consumption of whole wheat bread and cereal during childhood may be associated with the development of Crohn’s disease. Russel’s study compared the diet of 290 patients newly diagnosed with Crohn’s disease with 616 normal individuals and found that eating more than five citrus oranges per week significantly reduced the risk of the disease.
5, food additives
Swidsinski et al. used a mouse model of Crohn’s disease, fed drinking water containing 2% carboxymethylcellulose, and found that the number of ileal mucosal flora increased nearly 30,000-fold and induced ileal inflammation in the mice. A study just published in Nature this year evaluated both carboxymethyl cellulose and polysorbate 80, two common food emulsifiers, and found that they not only affect intestinal flora and induce enteritis, but also contribute to the development of metabolic syndrome.
Some processed foods such as jams, salad dressings and mayonnaise contain insoluble fine particles such as titanium dioxide (titanium dioxide) and aluminum silicates, which may act as antigens to stimulate inflammation of the intestinal mucosa. The diet of Western countries is rich in food particles, which may be one of the reasons for the high prevalence of Crohn’s disease, and the dietary survey conducted by Lomer et al. did not find any difference in the content of fine particles in the diet of Crohn’s disease patients and normal people.
II. Diet and disease activity
1. Fats and fatty acids
Ferreira and Guerreiro’s study found that a diet high in fat, saturated fat, polyunsaturated fatty acids, and high Omega-6/Omega-3 fatty acid ratios in Crohn’s disease patients led to more active disease, and that Omega-3 fatty acids (fish oil) are a common polyunsaturated fatty acid with immunomodulatory properties. However, two large randomized controlled trials failed to confirm their efficacy in Crohn’s disease. Olive oil is rich in oleic acid, a monounsaturated fatty acid. Some early studies found that foods prepared in olive oil may be more beneficial than the usual seed oils (corn oil, soybean oil) in reducing intestinal inflammation. Similar findings have been verified in animal studies.
In Japan, several university hospitals have tried to give Crohn’s disease patients a “semi-vegetarian” diet to reduce fat intake. The recurrence rate was significantly lower in patients who adhered to a “semi-vegetarian” diet. However, it was not clear whether the “semi-vegetarian” diet or other dietary modifications were responsible because the patients were also advised to reduce their intake of bread, sweets, margarine, cheese and fast foods.
2. Carbohydrates
Ritchie and Brandes’ study found that simply reducing refined sugar intake did not help improve symptoms in patients with Crohn’s disease. Bassaganya et al. found that resistant starch had a reducing effect on inflammation in an IL-10 knockout mouse model of Crohn’s disease, suggesting that resistant starch may be used to treat Crohn’s disease, but no clinical studies have been conducted in this area. There are three more popular dietary regimens used abroad to adjust carbohydrate intake in Crohn’s disease patients.
(1) SCD diet
The SCD diet is a special carbohydrate diet. This diet eliminates all complex sugars (lactose, sucrose), starches (corn, rice, flour), cereals, and legumes from the diet, which are more difficult to absorb, and retains only the monosaccharides (glucose, fructose, and galactose). Then slowly start eating cooked fruits and vegetables, and if tolerated, start eating a wider variety of foods, including meat. Although this dietary regimen is recommended by many inflammatory bowel disease websites abroad, and some believe it may improve symptoms and reduce medication use, the SCD diet regimen may lead to inadequate energy intake and weight loss. Moreover, there is a lack of objective evidence to confirm its efficacy in Crohn’s disease, and relevant clinical studies are still underway.
(2) Low FODMAPs diet
FODMAPs (fermentable oligo-, di-, and monosaccharides andpolyols) were first proposed by Gibson et al. and refer to fermentable oligosaccharides, monosaccharides, disaccharides, and polyols. These fermentable compounds are characterized by difficult absorption in the small intestine, high permeability and rapid fermentation by colonic bacteria, so the FODMAPs diet can lead to colonic dilatation and watery diarrhea. Patients with Crohn’s disease may develop functional gastrointestinal symptoms unrelated to intestinal inflammation, which cannot be relieved even with effective anti-inflammatory drugs. richard et al. demonstrated that a diet low in FODMAPs significantly improved functional gastrointestinal symptoms in patients with Crohn’s disease.
(3) Gluten-free diet
Gluten is not a carbohydrate, but a protein consisting of alcoholic and wheat gluten proteins. However, because gluten is mostly derived from foods processed from wheat, rye and barley, it is often accompanied by carbohydrates such as fructans. Patients with Crohn’s disease can have a combination of celiac disease or gluten allergy, which can lead to diarrhea and even intestinal inflammation after eating gluten, a difficult-to-absorb protein, so a gluten-free diet can be tried for symptomatic Crohn’s patients. However, there is no evidence to confirm the effect of this dietary regimen on the disease activity of Crohn’s disease.
3. Dietary fiber
There is a lack of clinical studies on the effect of dietary fiber on Crohn’s disease activity, and Ritchie et al. did not observe any improvement in symptoms after giving patients a high-fiber, low-sugar diet. Future studies should distinguish between different types of dietary fiber, especially soluble fiber and insoluble fiber. For Crohn’s disease patients with intestinal stricture, foods rich in insoluble dietary fiber, such as cruciferous vegetables, fruit rinds, and melon nuts, should be avoided to prevent the induction of intestinal obstruction.
4.Probiotics and prebiotics
Prebiotics are dietary supplements that have a beneficial effect on the host by selectively stimulating the growth and activity of one or a few intestinal strains. The most studied prebiotics include fructooligosaccharides and galactooligosaccharides, and several studies have confirmed their good efficacy in animal models of colitis. However, there are few clinical studies on them. Initial experiments by Lindsay found that fructooligosaccharides may have some efficacy in Crohn’s disease, but then a randomized controlled study by Benjamen found that they instead exacerbated the symptoms of Crohn’s disease.
Guslandi et al. found that the addition of Saccharomyces bovis was more effective than mesalazine alone in maintaining Crohn’s disease remission, whereas Lactobacillus rhamnosus had no such effect. In terms of inducing disease remission, neither E. coli Nissle 1917 nor Lactobacillus rhamnosus showed significant efficacy.
5.Food particles
Lomer et al. conducted a preliminary trial and found that for hormone-dependent Crohn’s disease patients, a diet with few food particles improved the disease. However, his subsequent multicenter clinical trials failed to confirm the effect of a food particle less diet on Crohn’s disease.
6. Individualized restrictive diets
A multicenter study in The Lancet randomized 78 Crohn’s patients in remission from enteral nutrition to two groups, one receiving an individualized restrictive diet and one receiving 12 weeks of hormone therapy. The individualized restricted diet group gradually returned to a normal diet, adding one food per day and eliminating one food once it was added with symptoms of diarrhea and abdominal pain. Ultimately, it was found that patients in the individualized restrictive diet group had a significantly lower rate of disease relapse. In this trial, the most common food intolerances of Crohn’s disease patients in the individualized restricted diet group were grains, dairy products, and fermented foods.
It is important to note that direct studies of dietary interventions in humans and observing the effects of specific diets are difficult to achieve, so most of the current studies are retrospective or epidemiological in nature. Moreover, because the evaluation of dietary structure is prone to error and bias, the conclusions drawn need to be treated with caution.
Enteral nutrition and Crohn’s disease
Enteral nutrition (elemental diet) is a form of nutritional support that provides metabolically required nutrients and various other nutrients via the gastrointestinal tract. It is administered by both oral and transcatheter routes. Among them, the transcatheter input includes nasogastric tube, nasoduodenal tube, nasojejunal tube and gastrojejunostomy tube. Enteral nutrition has become the internationally recognized drug of choice for the treatment of Crohn’s disease in children. It is as effective as hormones in inducing disease remission, avoids the adverse effects associated with long-term hormone use, and significantly improves the nutritional status of patients.
In adults with Crohn’s disease, clinical studies on enteral nutrition are much less available in comparison. Several meta-analyses and systematic reviews have found that total enteral nutrition is less effective than hormones in inducing remission in adults with Crohn’s disease, but considering that the dropout rate in the total enteral nutrition group can be as high as 25-40%, this conclusion needs to be further confirmed. The use of total enteral nutrition in the United States and Europe is very low because of its intolerability and impact on patient social behavior. In Japan, enteral nutrition is also mostly used as maintenance therapy or as an adjunct to therapy. In several treatment centers in Japan, patients are usually induced to remission by hormones or infliximab and then maintained in remission by semi-enteral nutrition (50% of calories are provided by self-administered nasogastric tube infusion of enteral nutrition at night and 50% of calories are provided by oral diet during the day). Although enteral nutrition is now very widely used, there are still some questions that need to be answered.
1. Total enteral nutrition or semi-enteral nutrition?
Is the main mechanism by which enteral nutrition can significantly reduce intestinal inflammation that the nutrients play an anti-inflammatory and promote intestinal mucosal healing role, or is it simply that the intestine gets a rest because of the cessation of normal diet? The remission rate was significantly lower in the hemi-enteral group than in the total enteral group (15% vs. 40%). Evidence suggests that the efficacy of enteral nutrition does not depend on its composition, but rather on whether the patient excludes the normal oral diet. However, the recurrence rate of Crohn’s disease in patients with semi-enteral nutrition is still significantly lower than in patients with an unrestricted diet.
2. Whole protein or amino acid formulations?
Two randomized controlled trials by Verma and Grogan confirmed that there was no significant difference in the efficacy of whole protein and amino acid formulations in inducing remission in both adults and children with Crohn’s disease, and a 2007 meta-analysis of 10 clinical studies confirmed that there was no difference in the efficacy of enteral nutrition with and without elements in the treatment of Crohn’s disease. This suggests that the mechanism of action of enteral nutrition in the treatment of Crohn’s disease is not related to the composition of enteral nutrition. Considering the low energy density and higher permeability of amino acid preparation, whole protein preparation is usually used abroad.
3. Nasal or oral?
Rubio et al. observed 106 pediatric Crohn’s disease patients receiving total enteral nutrition for 8 weeks and found no difference in disease remission rate and mucosal healing between patients on intranasal and oral nutrition. However, weight gain was more pronounced in patients on nasal nutrition than in those on oral nutrition. The infusion of enteral nutrition by nasogastric tube can ensure that the patient achieves the desired nutritional goals and effectively improves the nutritional status of the patient.
4.Weeks or months?
Currently, it is believed that 3-5 weeks of enteral nutrition therapy is sufficient to achieve remission in most patients with active disease, and Guo et al. found that 4 weeks of total enteral nutrition resulted in a substantial improvement in quality of life in adult Crohn’s patients, with 84.6% of patients achieving remission. A survey of 35 pediatric inflammatory bowel disease treatment centers worldwide found that the duration of enteral nutrition is typically 6-8 weeks. Our findings suggest that 12 weeks of total enteral nutrition helps to reduce intestinal luminal strictures in patients with Crohn’s disease, while 3 months of total enteral nutrition before surgery reduces postoperative complications in patients with Crohn’s disease enterocutaneous fistulas. Considering that about 50% of patients have disease recurrence six months after discontinuing enteral nutrition, extending the duration and increasing the frequency of enteral nutrition may result in better outcomes, but this remains to be proven.
IV. Dietary recommendations for Crohn’s disease
Because most studies evaluating diet and risk of Crohn’s disease have produced indirect evidence, current dietary recommendations for Crohn’s disease patients are conservative and cautious. Unreasonable restrictions on the intake of certain nutrients or foods may lead to nutritional imbalances and weight loss, which in turn may reduce the patient’s resistance and promote the progression of the disease. Based on the available evidence and guideline recommendations, we give the following dietary recommendations to patients with Crohn’s disease.
1, less intake of animal fat, less processed foods, more vegetables and fruits may be beneficial to reduce disease symptoms;
2, advocate individualized diet plan, establish a dietary diary, if symptoms worsen after eating a certain food, try it again, and exclude it after determining intolerance. The food that can be tolerated during the remission period may not be tolerated during the active period;
3. Under the premise of reasonable anti-inflammatory treatment, try SCD diet, low FODMAPs diet, gluten-free diet and “semi-vegetarian” diet as appropriate;
4. For patients with acute active disease or intestinal strictures, they should eat fewer and more frequent meals, eat an easily digestible low residue diet, and reduce the intake of dietary fiber, especially insoluble dietary fiber;
5. Patients with active disease should be induced to remission as soon as possible to prevent the progression of intestinal lesions from worsening. At this time, the dietary restriction should be more strict, and the use of total enteral nutrition can be considered.
V. Summary
Crohn’s disease is an immune disease that mainly involves the intestinal tract, and therefore diet is one of the most important concerns of patients. Although the role of diet in the development and recurrence of Crohn’s disease is not well understood, dietary modification and intervention for Crohn’s disease patients is essential, considering the effect of diet on intestinal mucosa and intestinal flora. Given that patients differ from each other in terms of body composition and condition, an individualized diet modification program may be the best solution.