• Highlights
• Introduction
• Causes
• Symptoms
• Complications
• Risk Factors
• Diagnosis
• Dietary Factors
• Symptom Management
• Medications
• Surgery
• Resources
• References

Crohn's disease

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of Crohn's disease.

Alternative Names

Inflammatory bowel disease - Crohn's disease

Dietary Factors

The role of diet and nutrition is very important in Crohn's disease and should be considered for four separate situations:

• As important add-on treatment to medical therapies for maintaining nutrition and correcting any nutritional deficiencies.
• As primary treatment for reducing disease activity.
• As maintenance therapy on a long-term basis in the case of severe intestinal failure or short-bowel syndrome.
• For reversing growth-failure in children.

Maintaining or Achieving Normal Weight

Malnutrition is very common in Crohn's disease. In fact, patients with Crohn's appear to burn fat calories at a higher rate than the general population and most patients are underweight. Some experts recommend that children with IBD increase their calorie and protein intake by 150% of the daily recommended allowance for their specific ages and heights. Studies indicate that nutritional support in children is as important as medications for achieving remission. People whose weights are normal or no less than 90% of normal do not need to add extra calories.

Foods Important for Protection

Fluids (non-caffeinated). Drinking plenty of water is extremely important. Vegetable juice and sports drinks may be helpful for restoring important minerals. Caffeinated beverages should be avoided in general, although green tea may have some benefits for Crohn's disease.

Protein. Proteins are very important for growth in children and for repair of cells. Diarrhea can cause protein deficiency and patients with IBD may need more protein than the general population. Patients should choose fish and soy as primary protein sources. One study reported that a soy protein diet was particularly useful for patients who were intolerant to milk products. Oily fish, such as salmon and tuna, may be particularly beneficial in Crohn's disease. Other options are poultry and lean meats. Dried beans and legumes also provide protein.

Complex Carbohydrates. Complex carbohydrates found in whole grains, fruits, and vegetables should make up half of a patient's calories. Fresh fruit (such as apples, grapefruit, oranges, plums, blueberries, raspberries, and strawberries) may actually be specifically protective for IBD and may possibly reduce the risk for colon cancer. (Simple sugars can increase inflammation, however, so patients should avoid dried fruits and high-sugar fruits, such as grapes, pineapple, and watermelon.)

Foods made up of complex carbohydrates are also often a good source of fiber, which may help reduce damage in the intestinal tract caused by inflammation. However, high-fiber foods can cause gas, bloating, and pain, particularly in IBD patients. Commercial products (such as Beano) are available that can reduce gas. Eating small, frequent meals can also help.

Fish Oil. Omega-3 fatty acids, which are found in oily fish, have been associated with protection against inflammation, including in the intestinal tract. Some studies have reported lowered use of anti-inflammatory medications in people who consume fish oil. Such fatty acids are also available in supplements as docosahexaenoic (DHA) and eicosapentaneoic (EPA) acids. Standards for optimal amounts and forms of omega-3 fatty acids have not yet been established, however.

Liquid Supplements. Over-the-counter liquid diets, such as Ensure, Sustacal, and others that meet full nutritional needs and are absorbed in the upper intestine may be helpful for some patients with Crohn's, but no studies have determined this.

Potassium-rich Foods. Examples are potatoes, avocados, and bananas.

Foods Associated with Higher Risk for Symptoms

Exclusion Diets. Exclusion diets are those that eliminate certain foods that may cause allergies or irritate the intestine. To determine these foods, patients use an "elimination/challenge" approach. First, they remove all suspect foods from their diet for 2 weeks and then reintroduce one food every 3 days. Patients then watch for any symptoms that might indicate an allergic or irritant response, including gastrointestinal problems, headaches, and flushing. Some experts believe, however, that this approach is very difficult, and studies are weak in confirming its value for maintaining remission.

Typical foods to avoid include:

• Fats. Fats appear to worsen intestinal inflammation in Crohn's disease. Patients should limit fats, particularly saturated fats, found in meat and dairy products. However, certain fatty acids, such as those found in fish oil, may be helpful. Experts are investigating the optimal balance between a low-fat diet with addition of these fatty acids.
• Milk products. Some people with IBD are lactose intolerant (unable to digest the sugar lactose, found in milk products). However, milk, along with the calcium it contains, have been associated with a lower risk for colon cancer. Taking lactase tablets or specially prepared dairy products may help. (Many lactose-intolerant patients are still able to eat yogurt with active cultures, which could be helpful for IBD.)
• Foods associated with inflammation (alcohol, simple sugars, and caffeine).
• Fruits may be protective, but patients should avoid dried fruits or high-sugar fruits, such as grapes, watermelon, or pineapple.
• Products containing corn or gluten (those made from wheat, oats, barley, or triticale).
• Common allergenic foods, such as soy, eggs, peanuts, tomatoes.
• Foods that may irritate the intestine, particularly so-called Brassica vegetables (cabbage, Brussels sprouts, broccoli, cauliflower, kale).

Dietary Considerations for Reducing Kidney Stones

Kidney stones are painful and common complications in IBD, particularly in patients who have had intestinal surgery. IBD patients are at risk for the most common types of stones -- those composed of either calcium oxalate or uric acid crystals. The following are some considerations in reducing the risk for stones:

• The most important dietary recommendation is to increase fluid and restrict sodium intake.
• Limiting protein is recommended for reducing kidney stones. However, people with IBD with frequent diarrhea are protein deficient. Sufficient protein, particularly in children with IBD, is very important and should be weighed against any risk for stones.
• Patients should increase intake of potassium-rich foods (bananas, watermelon, cantaloupe, oranges, tomatoes, beans).
• Patients should try to correct any dietary habits that cause acidic or alkaline imbalances in the urine that promote stone formation.
• Many kidney stones are formed from calcium-oxalate stones. Patients should avoid or limit intake of oxalate-rich foods, such as beets, beet tops, black tea, chenopodium, chocolate, cocoa, dried figs, ground pepper, lamb quarters, lime peel, nuts, parsley, poppy seeds, purslane, rhubarb, sorrel, spinach, and Swiss chard. A high calcium diet does not appear to increase the risk for kidney stones as long as it also contains plenty of fluids and dietary potassium and phosphate. Importantly calcium is associated with protection against colon cancer and osteoporosis -- two conditions that are associated with IBD.
• Patients who have stones associated with short-bowel syndrome should restrict their intake of fat as well oxalates. In such cases, calcium may bind to unabsorbed fat instead of to oxalates, which increase oxalate levels.

The general recommendations for avoiding kidney stones need to be tailored to the dietary requirements of IBD. Patients should work with their doctors to develop an individualized plan.

Probiotics and Prebiotics

Researchers are currently investigating bacteria (called probiotics) and specific foods (called prebiotics) that are metabolized by these bacteria, and the compounds they produce (called synbiotics). Some evidence suggests that alone or in combination, they may have significant benefits in the intestine.

• Probiotics are bacterial strains that by themselves may provide a barrier against harmful bacteria, possibly through various mechanisms such as excreting certain acids (lactate, acetate) that inhibit harmful bacteria or compete with them for nutrients. It has been suggested that probiotics may help maintain remission in patients with IBD. The specific bacterial strains that might be beneficial, however, are not fully known. The most well-known probiotics are the lactobacilli strains, such as acidophilus , which are found in yogurt and other fermented milk products. Others, however, may prove to be more important, such as bifidobacteria and GG lactobacilli. Other probiotics that may be beneficial for patients with IBD include lactobacilli rhamnosus , casel , plantarium , bulgaricus , and salivarius , and also Enterococcus faecium and Streptococcus thermophilus .
• Prebiotics are specific non-digestible molecules called fructo-oligosaccharides (FOS), which stimulate the growth of probiotics. FOS are found in many foods, including Jerusalem artichokes, onions, salsify, bananas, honey, garlic, and leeks. (However, some of these foods can irritate the intestine in patients with IBD.)

Researchers are investigating probiotics, prebiotics, or both for intestinal protection, including benefits for patients with IBD. Foods and supplements containing these substances are available in the U.S. and are heavily marketed in Europe, Japan, and Australia. To date, however, no studies have determined any clear benefits of any specific organism or formulation.

Vitamins and Other Supplements

Crohn's disease and surgical procedures that remove parts of the small intestine can inhibit absorption of vitamins, fats, and other important supplements. Taking certain supplements, such as fish oil, antioxidants, and mineral supplements may be beneficial for patients with Crohn's disease.

Vitamins. Deficiencies of vitamins A, C, D, E, B12, and folate (a B vitamin) may result from malabsorption. In general, vitamin supplements may be recommended for everyone with IBD, particularly for children to avoid growth retardation. Vitamins A, C, and E are antioxidants, which are scavengers of damaging particles in the body. Folic acid supplements are particularly important for patients who must restrict fresh fruits and vegetables and for those taking sulfasalazine. Folate deficiencies may contribute to the increased risk for colon cancer. Monthly injections of vitamin B-12 may be necessary. Vitamin D is necessary for bone protection. Because some vitamins, such as A and D, can be toxic at high doses, patients should discuss specific dosages with their doctors.

Omega-3 Fatty Acids. The role of fats in inflammatory bowel disease is complex and not fully known. Some evidence suggests that patients with Crohn's burn fat calories at a higher rate than the general population. Patients with IBD may be deficient in essential fatty acids, particularly omega-3 fatty acids (polyunsaturated fats found in oily fish and certain vegetable products such as flaxseed and canola oils). Such fatty acids are also available in supplements as docosahexaenoic (DHA) and eicosapentaneoic (EPA) acids, which are specific compounds found in fish oil.

Mineral Supplements. Supplements of calcium, magnesium, zinc, selenium, and iron may be needed to offset deficiencies in patients with severe IBD.

• Calcium and magnesium are critical for health and strong bones. Many patients with IBD suffer from calcium and vitamin D deficiencies, which cause low bone density. Studies indicate that calcium and vitamin D supplements may be adequate to increase bone density without drugs.
• Selenium is a potent antioxidant.
• Zinc is important for wound healing, and deficiencies may promote fistulas in Crohn's disease.
• Iron supplements may be required for anemia. However, iron overdose is very dangerous. As few as three adult iron tablets can poison children, even fatally. No one, even adults, should take a double dose of iron if one is missed. A doctor should advise patients on correct dosage.

Diets as Primary Treatment for Severe Malnutrition

Enteral Nutrition. Enteral nutrition uses a feeding tube that is inserted either through the nose and down through the throat or directly through the abdominal wall into the gastrointestinal tract. It is the preferred method for feeding patients with malnutrition who cannot tolerate eating by mouth. The nutritional formulas used in enteral administration include:

• Polymeric diets (containing a balance of standard nutrients).
• Elemental diets (predigested nutrients that are absorbed in the first meter of the small intestine). These diets are used less commonly than polymeric diets.

In children, enteral nutrition is given for 6 - 8 weeks. Simple foods are then introduced (chicken, potato, rice), and more complex foods (milk, fiber, wheat-based foods) are then added gradually. However, relapse is still common.

A major 2002 analysis did not confirm any advantages of enteral feedings over corticosteroids, nor did it find any additional benefits from elemental diets compared to polymeric diets. Still, they may be helpful for specific patients. For example, in a 2001 study of children with steroid-dependent Crohn's disease that was already in remission, elemental supplements allowed many of them to withdraw from the medication. Further research is needed to determine if there is an optimal balance of nutrients in the enteral diet formula for IBD that might improve their effects.

Total Parenteral Nutrition. Total parenteral nutrition (TPN), or hyperalimentation, is the intravenous administration of nutrients through an indwelling catheter (tube). It is used for very severe IBD when patients cannot tolerate any nutrition by mouth or with a feeding tube, and may even be useful as a primary therapy for patients with Crohn's (although not for those with fistulas). It is usually administered in the hospital, although increasingly people are self-administering it at home. The procedure carries a risk for complications, some serious, including infection, blood clots, and liver failure.

• Review Date: 3/6/2007
• Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli A. Stacy. Previously approved by Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital (8/21/2006).

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