Ask the Doctors

Dear Doctor: What causes Crohn's disease? My grandson has had two surgeries for it. Did the food he ate while growing up cause it? I have heard that it is genetic, but we don't know of anyone in his family who has had it.

Dear Reader: It's understandable to want answers about Crohn's disease. A type of inflammatory bowel disease, Crohn's ultimately affects multiple portions of the body, but specifically the large and small intestine, causing diarrhea, abdominal pain, cramping, fatigue, reduced appetite and weight loss. About one in every 500 people within the United States has the disease, and it's most often diagnosed among teenagers and young adults.

And yes, there is a genetic component. About 20 percent of people with Crohn's have a family member with an inflammatory bowel disease, and having a sibling with Crohn's disease increases the risk of getting the disease thirtyfold. For identical twins, the link is even stronger. They have a 50 percent risk of developing the disease if one of the twins has it.

A family history of Crohn's disease isn't the only risk factor. Current and former smokers appear to be at increased risk, as are people who have taken antibiotics or who have had a gastrointestinal infection. Factors that can slightly boost the risk are not having been breast-fed, obesity, chronic use of nonsteroidal anti-inflammatory drugs and the use of oral contraceptives.

That brings us to your question about diet. The rate of Crohn's disease is increasing in the United States and Europe, especially among children. A low-fiber diet appears to be a significant factor. The Nurses' Health Study showed that people who had a higher fiber intake from fruits and vegetables had a 40 percent reduced risk of the disease. Conversely, consumption of saturated fats, processed meats and polyunsaturated fats has been associated with increased incidence of the disease, as have diets high in refined sugar, such as from desserts, candies and sodas.

Many doctors believe that Western diets increase permeability of the intestine, making the intestine more vulnerable to injury. Also, our diets may change our intestinal bacteria in a way that promotes inflammation, leading in turn to Crohn's disease.

To manage Crohn's disease, eliminating foods that have caused past flares will reduce the chance of another flare, as will increasing the amount of dietary fiber and exercise. Because lack of sleep, stress, anxiety and depression can exacerbate the disease, maintaining good mental and emotional health is vital.

On the plus side, therapies have improved. Newer treatments with injectable biologic agents have shown greater efficacy than traditional drugs against Crohn's disease in those with severe cases, even reversing the disease in many patients so that they don't need surgery to remove damaged portions of the bowel.

In short, a myriad of factors could have led to your grandson's disease. What's important now is to ensure that he maintains a proper diet; gets enough sleep and exercise; and limits his stressors.

(Send your questions to, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

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