Did you know that dietary fiber intake can affect your irritable bowel syndrome (IBS) symptoms?
Irritable bowel syndrome (IBS) is a condition characterized by abdominal (belly) pain and abnormal bowel habits (such as diarrhea, constipation, or a combination of both), bloating, distension, and excessive flatulence (gas). The amount of dietary fiber you eat also plays a role in managing symptoms and normalizing bowel habits. In IBS, too much or too little dietary fiber can affect symptoms, and certain types of dietary fiber may be better tolerated than others.
Working with a dietitian can help get you started to consider the effect of dietary fiber on your IBS symptoms.
What is dietary fiber?
Fiber is the non-digestible, carbohydrate component of plants foods. These are fruits and vegetables, whole grain breads and cereals, legumes, nuts and seeds. Fiber can either be consumed from food or taken as a supplement (for example bran, psyllium and methylcellulose).
Fiber has several beneficial effects for our bodies. For example, fiber helps to:
- Lower blood glucose levels
- Lower cholesterol levels
- Lower blood pressure
- Increase satiety (the feeling of fullness after a meal)
- Improve laxation (through increased stool bulk and viscosity)
- Feed our gut bacteria (acting as a prebiotic- increasing bacterial numbers and improving bacterial composition)
- Increase production of beneficial fermentation by-products (the compounds produced when fiber is broken down by our gut bacteria)
Many foods can be classified as fiber, and different types of fiber can affect the way they behave in our gut, and how well tolerated they are in patients with IBS. Characteristics that vary between fibers include their chemical structure, chain length (molecular size), solubility (ability to dissolve), viscosity (ability to thicken liquids once dissolved), and fermentability (extent and rate at which our gut bacteria break them down). In IBS, the fermentability of fiber may be particularly important.
Readily Fermentable fibers
As the name suggests, readily fermentable fibers are easily and quickly broken down by our gut bacteria, producing gases and other fermentation by-products. Examples include inulin, fructo-oligosaccharides (FOS) and pectin, which are often added to manufactured foods ranging from yogurts and snack bars to bread products to make them “high fiber.” The gas and other by-products produced via the fermentation of these fibers may cause problems in some people with IBS.
Getting enough fiber
Too much dietary fiber can cause a problem for people with IBS, but for most people, the problem is eating too little fiber. Despite recommendations that adult women consume 25g fiber per day and men consume 38g fiber per day, the average fiber intake is just 16g fiber per day. There are a number of reasons for this poor fiber intake: Beliefs that all grain based foods are good sources of fiber; uptake of gluten-free, wheat-free, and grain-free diets which limit or eliminate fiber-rich grains from the diet; and beliefs that high fiber foods are expensive, unpalatable, and complicated to prepare.
If you have IBS, not eating enough fiber can make symptoms worse (such as constipation and abdominal pain); however, eating enough fiber can help to relieve symptoms. Eating enough fiber is easier than you think with a few small changes to your diet.
|Tips to achieve adequate fiber:
· Snack on fruits (e.g., raspberries, rhubarb, kiwifruit, mandarin, strawberries, passionfruit and oranges)
· Include vegetables with meals (e.g., carrot – skin on, green beans, potato – skin on, corn, eggplant)
· Check food labels when buying bread and cereal products. Compare products in the per 100g column to find higher fiber options. Examples include quinoa flakes, brown rice, gluten-free multigrain bread, rice bran, sourdough spelt bread and porridge (oats).
· Add canned lentils/ canned chickpeas to a casserole/salad
· Snack on nuts (e.g., macadamias, almonds, and peanuts)
· Add rice bran or linseeds/flax to breakfast cereal
Note: Wheat bran is not recommended in IBS.
Also, when increasing fiber intake, do this gradually, so your bowel has time to adjust.
Adapted from IFFGD Publication #129 Fiber in IBS by Dr. Jane Varney & Associate Professor Jane Muir; Department of Gastroenterology, Monash University, Melbourne, Australia. Edited by: Shanti Eswaran MD, Associate Professor, Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI