Can Fiber Wreck Your Race?
We all know that fiber is an important part of a healthy training diet, but what exactly does fiber do and can it lead to gastrointestinal (GI) upset during a race?
Fiber is the part of a plant/grain that the body cannot digest or use for fuel and is an important part of the diet for numerous reasons. There are two types of fiber, soluble and insoluble.
Soluble fiber, while in the GI tract may help to lower LDL (bad) cholesterol, by trapping the cholesterol in the gut and not allowing absorption into the body. Soluble fiber also helps to maintain blood glucose levels and aid in metabolic function. Consuming high levels of fats along with soluble fiber may cause loose stools, another unwanted problem on race day. Foods high in soluble fiber include oat bran, oatmeal, beans, peas, rice bran, barley, citrus fruits, strawberries and apple pulp. According to the American Heart Association, soluble fiber has been associated with increased diet quality and decreased risk of cardiovascular disease.
Insoluble fiber is the type of fiber that typically concerns athletes due to its ability to cause lower GI problems on race day. Foods high in insoluble fiber include whole-wheat breads, wheat cereals, wheat bran, rye, wild rice, barley, most other grains, cabbage, beets, carrots, brussels sprouts, turnips, cauliflower and apple skin. Insoluble fiber, as the name suggests, simply passes through the GI tract adding more bulk and absorbing water into the stool, promoting proper bowel function. This is not to say that if you eat no fiber you will have no waste; it will just be less bulky. The reason a high fiber diet is an important part of an athletes diet is two fold; one, it slows digestions of other carbohydrates by prolonging gastric emptying. This increases satiety, and may help prevent overeating, as well as prevent blood glucose spikes and valleys (i.e. sugar high and crash). As a result, your body receives a steady glucose supply. The second reason insoluble fiber should be incorporated into your diet is that it helps to cleanse the bowel by maintaining optimal bowel pH as well as remove dead cells and other debris, which in turn can prevent diverticulosis and possibly colon cancer.
Daily dietary fiber intake among adults in the United States averages about 15 grams. The Institute of Medicine recommends consuming 14 grams of fiber for every 1,000 calories which, for most, correlates to a daily requirement of 25-35 grams of fiber, although athletes may require more based on a higher caloric intake. It is important to understand that hydration and dietary fiber are interconnected and the proper combination of both is required for a healthy GI system.
A common problem in triathletes, particular during longer races, is GI distress during competition, particular while running. Every athlete’s body will respond differently to the stress of race day and no single fiber protocol will work for everyone. However, because fiber adds bulk to the stool and or loose stool, eating a diet low in both types of fiber for one or two days leading up to a race may help to ward off lower GI problems. If this does not help, some may recommend taking an anti-diarrheal agent, such as immodium prior to or even during the race. However, carefully follow the recommended dosage and do not take more than suggested on the package. As always practice any race protocol in training or lower priority races.
The bottom line is 25-35g of fiber from a variety of sources is an important part of a healthy training diet. However, reducing fiber intake prior to a race may prevent frequent stops on the run course.
