Crohn's and colitis - dietary considerations

Crohn's disease and ulcerative colitis are collectively known as inflammatory bowel disease (IBD). Both conditions affect the bowel, but in slightly different ways. Crohn's disease causes inflammation of the full thickness of the bowel wall and can target any part of the digestive tract, from mouth to anus. Ulcerative colitis is inflammation of the large bowel (colon and rectum). The causes of IBD are unknown, but researchers suspect either an autoimmune reaction or some kind of infection. There is no evidence to suggest that diet plays a part in the development of IBD. However, making certain dietary adjustments can help manage some of the symptoms of IBD, and allow the various medications commonly used to treat this condition to work more effectively.

Digestion and absorption explained

Food is broken down by mechanical and chemical means, in the mouth and stomach. When the food has reached a pulp-like consistency, it is slowly released into the first part of the small intestine (ileum). The food is then massaged along the length of the small intestine. Organs like the pancreas and the gall bladder contribute digestive enzymes to further break down the food into its simpler components. The small intestine is lined with microscopic finger-like projections (villi) that lie close to tiny blood vessels (capillaries). Nutrients are passed into the bloodstream through these villi. The remainder of the food is pushed into the large bowel, where excess water is absorbed. The waste is then temporarily stored in the colon before it is eliminated from the anus.

IBD, digestion and absorption

Crohn's disease and ulcerative colitis disturb the digestion and absorption processes in different ways.

• Crohn's disease - an inflamed ileum impairs absorption of vitamin B12 and bile salts. Inflammation along the length of the small intestine impairs absorption of all food nutrients. Inflammation of the large bowel impairs water absorption, which causes diarrhoea.
• Ulcerative colitis - digestion and absorption are generally unaffected. Inflammation of the large bowel impairs water absorption, which causes diarrhoea.

Other contributing factors
Other factors that may affect a person's nutritional status include:

• Medications - some drugs used to treat IBD may cause appetite loss and interfere with the absorption of certain nutrients, such as folic acid.
• Inflammation - the body needs greater amounts of nutrients in order to cope with inflammation and fever.
• Surgery - some people with IBD have had surgery to remove parts of their small intestine, which decreases nutrient absorption.

Problems caused by inadequate nutrition

Over the long term, reduced absorption of food nutrients can cause a number of problems, including:

• Anaemia
• Weight loss
• Impaired growth and development (in children).

There is no special diet

IBD is not caused by diet or allergies to certain food components. There is also no evidence that long term special diets are effective in treating IBD. However, some people may find that slight dietary adjustments help them to manage the symptoms of IBD.

Alterations to diet

Some of the dietary changes that may be appropriate for a person with IBD include:

• Low fibre diet - when IBD is active, most people find a bland, low fibre diet helps to ease diarrhoea and reduce abdominal cramping. People with Crohn's disease who have a narrowed small intestine may need to eat a low fibre diet most of the time.
• Low fat diet - people with Crohn's disease who experience steatorrhoea (diarrhoea that contains undigested dietary fats) may benefit from a low fat diet.
• Low lactose diet - the milk sugar lactose is broken down by the enzyme lactase, commonly found in the lining of the small intestine. Some people with Crohn's disease may lack this enzyme, so limiting milk and milk products may be helpful. Lactose intolerance can be diagnosed with a simple test. Consult with your doctor.
• Liquid diet - a person with severe Crohn's disease may need a nutritionally balanced liquid diet.
• Plenty of water - people with IBD need to drink plenty of fluids to prevent dehydration.

Vitamin and mineral supplements

If a person with IBD eats a varied diet, there is no need to take vitamin supplements. However, if dietary deficiencies are suspected, oral tablets or occasional vitamin injections may be needed. For example, a person on a low fibre diet may need vitamin C and folic acid supplementation because they don't consume enough fruit and vegetables. A person with Crohn's disease who experiences steatorrhoea may need calcium and magnesium supplements. Almost all children with IBD are advised to take supplements to guard against the possibility of impaired growth and development. Be guided by your health care specialist or dietitian.

Seek medical advice

Always consult with your doctor, health care specialist or dietitian before making any changes to your diet. This is particularly important in the case of children with IBD. Self-imposed restrictive diets of any kind often lead to nutritional deficiencies.

Where to get help

• Your doctor
• Gastroenterologist
• Crohn’s & Colitis Australia™ (CCA) Tel. (03) 9815 1266 or toll free 1800 138 029.

Things to remember

• Crohn's disease and ulcerative colitis are collectively known as inflammatory bowel disease (IBD).
• There is no evidence to suggest that diet plays a part in the development of IBD.
• Making certain dietary adjustments can help manage some of the symptoms of IBD and allow medications to work more effectively.
• Depending on the symptoms, dietary modifications may include low fibre diets, low fat diets or low lactose diets.
• Always consult with your doctor, health care specialist or dietitian before making any changes to your diet.

You might also be interested in:

• Collagenous colitis and lymphocytic colitis.
  
• Crohn's and colitis.
  
• Crohn's and colitis - complications.
  
• Digestive system.
  

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Last reviewed: October 2012

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Crohn's disease and ulcerative colitis are collectively known as inflammatory bowel disease (IBD). Making certain dietary adjustments, after consultation with your doctor, can help manage some of the symptoms of IBD. There is no evidence to suggest that diet plays a part in the development of IBD.

Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.

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