The dietary management of Chron's Disease

Chron's disease (CD) is an inflammatory condition that can potentially affect any part of the gastrointestinal tract. The causes of this disease are unknown, although genetic risk factors also exist.

CD prevalence is approximately 0.5-1/1000 (lower in Asian people), and it is higher in women than in men.

Common symptoms include diarrhea and urgency to defecate, abdominal pain, weight loss, and failure to thrive. Fever, malaise, anorexia are other possible symptoms.

For many patients, this is a brutal disease that interferes with everyday activities and can hinder sexual life. Also, CD patients often feel they are dealing alone with their problem.

The disease manifests itself with aphthous ulcerations, abdominal tenderness, perianal abscess, and fistulae, as well as anal strictures. The most severe complications include small bowel obstruction, toxic colonic dilatation (when the colon diameter gets larger than 6 cm[1]), bladder, colovaginal, or perianal fistulae (present in 10% of CD cases), gut perforation, rectal bleeding, colon cancer, fatty liver, cholangiocarcinoma, renal stones, osteomalacia, malnutrition, and amyloidosis.

Granulomas are a useful histopathological feature that allows the distinction between CD and other conditions. Since one-fifth of cases have microscopic granulomas, doctors formulate a diagnosis after performing a colonoscopy associated with rectal biopsy, the latter to increase specificity.

Nutritional deficiency is often a consequence of inflammatory diseases (such as celiac disease), and CD is no exception to this rule. However, the steroid medications prescribed to CD patients also increase the risk of osteoporosis and other bone-associated diseases. Therefore, a correct nutritional management of this disease is desirable. To quit smoking is also highly recommended since this habit is a known cause of chronic inflammation.

Poor treatment, nutritional issues, reduced absorption, inflammation, and intestinal bleeding are all possible consequences of anemia for IBD patients. Functional bowel symptoms are common among CD patients, as they are in ulcerative colitis.

Surgery

Up to 70% of CD patients undergo surgery within five years from the diagnosis. The rates of patients undergoing surgery vary across countries. The most common surgery for the management of CD is proctocolectomy, which involves removing a part of the small area of the bowel. Surgery may take place without any partial removal of the rectum or the colon.

The Dietary Management of Chron's Disease

According to the British Dietetic Association, the dietary management of CD builds upon the following four pillars:

1. use of enteral nutrition during acute disease stages to induce remission.
2. Maintenance of disease remission.
3. Application of strategies that can ease the clinical symptoms of the disease.
4. Treatment of possible complications, particularly malnutrition.

1. Diet Therapy for Easing Symptoms of Active Disease

Formula diets, also known as exclusive enteral nutrition (EEN), may help treat active CD. EEN provides 100% of the daily nutrient requirements through liquid nutrition formula supplemented to the patients either orally or via a feeding tube. Randomized controlled trials in children and adolescents have shown a remission rate close to 80%. 

Other types of feeds to support remission include elemental (amino-acid based), semi-elemental (oligopeptide), and polymeric (whole protein) formulas. Elemental feeds, in particular, are used in case of severe malnutrition.

The prescription for EEN is usually 6-8 weeks. However, the optimal length may vary depending on the patient's needs and can span between 2 and 12 weeks. Close dietary monitoring is critical for adequate recovery. The remission phase usually starts ten days after the EEN prescription. An EEN of 8 weeks may be suitable for complete mucosal healing.

Partial enteral nutrition therapy (between 30 and 50% of calories come from formula and the remainder from regular food) has also shown promising outcomes for inducing prolonged remission in CD patients. In this case, a prolonged provision that spans over 12 months may help reduce the chances of surgical treatment and enhance medication efficacy.

Weight loss is a potential problem when using a formula diet in CD patients, and it is usually due to inadequate nutrition intake in the first few days. If the weight loss persists for a few weeks, it is critical to increase the feed quantity and monitor tiredness symptoms.

Encouraging rest is critical for dietary management outcomes. Inadequate fluid intake may trigger postural hypotension when the blood pressure drops when standing up after sitting or lying down. In the case of hunger, increasing the amount of feed and monitoring adequate fluid intake can help. Headaches may indicate dehydration or may be due to withdrawal of caffeine.

Infrequent side-effects of the formula diet include diarrhea and the fact that many patients might not find the taste appealing to their buds. However, diluting the formula product with water may help prevent diarrhea by reducing the formula's osmolarity; patients usually get accustomed to the formula's taste after some time. Offering a range of flavors or pouring the formula in a cup or glass with a straw to drink can also improve acceptability by the patient.

2. Maintenance of disease remission: food reintroduction after EEN

There are no detailed guidelines on how to reintroduce foods during the remission phase that follows EEN. Introduction of individuals foods or food groups and a low-fat or low fiber diet seem to help. What is instead known is that high-fiber diets are discouraged during the reintroduction period. Therefore, low-fiber diets are highly encouraged and are considered superior to both exclusion and elimination diets in terms of their nutritional value.

The LOFFLEX diet (LOw Fat/ Fibre Limited EXclusion diet) can be a useful food reintroduction strategy. Patients can follow this diet for 2-4 weeks as they begin to substitute EEN with everyday foods. Besides, if the patient remains in a remission state, it is possible to reintroduce 20-25 foods over 3 to 4 days.

Higher fiber intakes are recommended during the remission phase. CD patients can progressively increase their fiber intake a few weeks after the remission start.

In the case of strictures in CD patients, it is useful to limit fiber intake to reduce bowel obstruction risk. The patient should avoid both high-fiber foods (whole grain cereals, legumes) and foods that are difficult to break down mechanically (such as cartilage, skin on meat, or fish).

3. Foods that can ease clinical symptoms of the disease

Patients should avoid foods that make their symptoms worse. In particular, a low FODMAP diet may help to relieve symptoms of functional bowel in CD such as pain in the abdomen, bloating, and diarrhea. Most patients report alleviation in symptoms already after six weeks they had been following this diet. However, avoidance of food items that contain essential nutrients is not encouraged.

Substitution of some long‐chain triglycerides with medium‐chain triglycerides, or dietary fortification with carbohydrate polymers, may be necessary. Also, patients who have a low BMI, or short bowel syndrome, might need parenteral nutrition.

4. Malnutrition and Nutritional Deficiencies

Malnutrition is a primary characteristic of CD and characterizes 85% of patients; weight loss is also common. Since the prevalence of obesity is growing, the current malnutrition rates connected to CD may be underestimated. 

Multiple factors cause malnutrition in CD patients. These may include protein loss from the bowel, poor absorption of food nutrients, cytokine-induced anorexia. An increased resting energy expenditure is another malnutrition cause in these patients. CD patients may also be at significant risk of developing nutritional deficiencies because of the substantial risk of poor absorption and inflammation due to narrowed bowel resections. There is additional risk due to repeated surgeries if postoperative complications prevail in the form of strictures and fistulas.

Approximately 40% of children and young people with CD have growth issues. Up to 60% of patients report a loss of both muscle and fat stores. Increasing risks related to malnutrition necessitates a regular assessment of the nutritional status and growth monitoring in children.

CD patients may struggle initially to eat sufficient amounts of food. The inclusion of small frequent meals that are high in protein is therefore strongly encouraged. Supplements may be useful, as are foods with a high nutrition density (such as those rich in healthy fats: fatty fish, avocado, olive oil, nuts). To ease stool movement, it helps increase fluid intake, especially during the disease's active phase.

Common deficiencies in CD patients include: zinc, folate, copper, iron and beta-carotene, and essential vitamins including B6, B12, E, C, and D. These deficiencies may also persist during remission, and their prevalence may not necessarily imply inadequate dietary intake, while instead, a decreased absorption in the bowel. In cases where diarrhea persists, poor absorption of essential nutrients such as iron, zinc, sodium, magnesium, and potassium may lead to anemia, dehydration, and malnutrition.

Routine multivitamin supplementation can help with the dietary management of CD patients.

A decreased intake and malabsorption of macro‐ and micronutrients put CD patients at risk of nutritional deficiencies and negative nitrogen balance. The latter occurs when the nitrogen output with urines is greater than the amount obtained from dietary proteins. A poor appetite, and side effects of medications may also contribute to this problem. A deficiency in vitamin B12 associated with lactase deficiency can also cause small intestinal bacterial growth, which exacerbates gastrointestinal symptoms.

CD patients often limit their dairy products intake during their remission period, therefore reducing their calcium intake. This behavior is particularly problematic for bone health, considering that vitamin D deficiency is ubiquitous among CD patients. Osteoporosis is widespread among CD patients. Bowel inflammation may also lead to protein malabsorption, which can also exacerbate osteoporosis since half of the bone mass is made of protein.

The recommended daily calcium intake in adults is 1000 mg (1200 mg in postmenopausal women and the elderly). Calcium should be preferentially obtained from dietary sources. In addition to calcium, iron deficiency is primarily remarked as the cause for anemia among CD patients.

It is not clear whether or not a vitamin D deficiency contributes to the severity of the disease. Whether an insufficient exposure to sunlight or inadequate food intake, especially dairy foods, is linked with the disease's severity is also unclear.

Conclusion

CD is a complex disease that has many debilitating consequences for patients, including a considerable malnutrition risk. Exclusive enteral nutrition is a good option for treating the acute phase. However, there is no agreement on what constitutes a specific reintroduction diet or what diet to follow during the remission phase. Many patients tend to exclude foods that they think could make their symptoms worse, particularly dairy products, increasing their risk of nutritional deficiencies. A low-fiber diet can help reduce the risk of re-acutization immediately after remission, although in the long term fiber intake should be increased.

[1] This condition is more common among patients with ulcerative colitis.