Fiber and Functional GI Issues

In the world of pelvic rehab, fiber is a big deal. Regardless of the diagnosis that brings the patient in to our clinic, bowel dysfunction is often a complaint that can aggravate or complicate any other diagnosis. Most of us are familiar with dietary fiber basics, but what do we know beyond those basics?

Put simply, there are 2 types of fiber: soluble and insoluble. According to Medline Plus, the average American eats 10-15 grams of fiber per day, when the recommended intake for older children, adolescents, and adults is 20-35 grams. (A high fiber fruit, a medium apple has 4.4 grams of fiber, just for perspective.) Soluble fiber, such as oat bran, nuts, seeds, beans, attract water and turn to gel during digestion. This helps to slow digestion, whereas insoluble fiber, found in wheat bran, vegetables, and while grains, speeds passage of food through the stomach and adds bulk to stools.

According to Eswaran & colleagues (2012), fiber is a crucial part of the digestive process. Any undigested carbohydrate that reaches the colon can be completely or partially fermented by the gut bacteria. Fiber fermentation can indirectly increase fecal bulking, and water retention (influenced by fiber type) can also affect bulk of stool. A potential negative aspect of fermentation is gas production that can cause bloating, discomfort, and flatus.The level of fermentation and solubility of different types of fiber varies based on chemical composition. For more details about the benefits of fiber related to fermenting and non-fermenting properties, click here for a full text article describing these processes.

In the article by Eswaran et al., the authors describe how insoluble fiber can have a laxative effect through mechanical stimulation/irritation if the fiber particles are sufficiently course and large. Soluble, viscous fibers can soften hard stool OR firm loose stool via its water-holding and gel-forming capabilities. While the authors point out varied types of fiber and the research about potential risks and benefits of each in patients with irritable bowel syndrome (IBS), the results of the research are often "mixed." This same phenomena can be seen in our patient populations: each person may need to tailor the amount and type of dietary fiber to her own body.

In relation to dietary fiber supplements, the highest level evidence(Level IIB)cited in the same article is for psyllium/ispaghula. While some patients consume psyllium that is recommended by a medical provider such as Metamucil, many patients choose to purchase the same product (minus the added preservatives) and add psyllium to their diet. While there are many studies that examine the effects of adding a fiber supplement, few actually study the effects of whole foods as the treatment.

One of the most important concepts to teach patients when they are adding fiber to their diet is to do so gradually, as a sudden increase can cause bloating, abdominal gas, and discomfort. If you are interested in learning more about pelvic rehabilitation for functional gastrointestinal disorders, come to PF2A, or attend the new-this-year Bowel Course happening next in November in California. Sign up early for the next 2A course, as the remaining 2013 courses have sold out!