Inflammatory bowel disease and dietary fiber

December 12, 2016
Inflammatory bowel disease (IBD) primarily refers to Crohn’s disease and ulcerative colitis, conditions in which inflammation in the gut can lead to damage of intestinal tissues and symptoms such as abdominal pain and diarrhea. Dietary fiber can be friend and foe to people with IBD. Whole foods that are high in fiber can make symptoms worse during a flare-up, but they can also help prevent future flare-ups during remission.   

What is dietary fiber?

Dietary fiber is a carbohydrate-like nutrient that our bodies can’t fully digest, so it travels through our gut to feed microbes and sweep out the intestine. Dietary fiber is found in a variety foods, but the highest levels are in healthy whole foods such as fruits, vegetables, nuts and whole grains. 

Our bodies don’t make enzymes to break down dietary fiber, so we can’t digest this nutrient. But the bacteria that live in our gut  do have the right enzymes, so they break it down and use it for food. This is crucial because healthy bacteria in our gut support our immune system and our intestinal cells. 

There are two types of fiber in foods: soluble and insoluble.

Soluble fiber 

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Soluble fiber is aptly named for its ability to dissolve in water. In the digestive system it forms a gel when it comes into contact with water or other liquids. This slows down digestion and helps foods move through the gut. Foods that are high in soluble fiber include avocados, bananas, legumes and oatmeal.

Insoluble fiber 

Insoluble fiber does not dissolve or mix with water. It is the “roughage” type of fiber that helps sweep out the gut like a broom and adds bulk to stools. Foods that are high in insoluble fiber include bran, leafy vegetables, fruit and root skins, seeds and nuts. 

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What to do for IBD

During an IBD flare-up, dietary fiber can worsen gut irritation, especially the broom-like insoluble fiber. Sometimes soluble fiber is a little gentler but it’s best to avoid all fiber, even in healthy whole foods, during a flare-up. This gives the gut time to rest and heal.

During remission, it’s important to regularly eat healthy whole foods with both types of fiber because they will feed the healthy bacteria and help prolong remission. 

If you’d like to learn more about the role of dietary fiber in IBD, this study is a good place to start. The Academy of Nutrition and Dietetics offers healthy eating tips for people with IBD.

Our registered dietitian nutritionists also can help you manage IBD with a healthy diet. Come visit Swedish’s new Bariatric, Metabolic and Endocrine Center. Call 206-215-2440 for an appointment.