Most people know that fiber is important, but do they really know what it is and why? Fiber is the non-digestible carbohydrate portion of food. The digestive system breaks down other carbohydrates, protein and fat for energy and growth, but it is unable to digest fiber in the small intestine. Instead, it passes along to the large intestine where it plays a very critical role in digestive health, heart disease, diabetes control and weight management.
Typically, fiber-containing foods are plant-based and include fruits, vegetables, grains, nuts, seeds and legumes. There are two major types of fibers found in these foods, soluble and insoluble, and a food can contain both fiber types. Soluble fiber dissolves in water and forms a gel-like substance in the gut, which is then further fermented by gut bacteria. Insoluble fiber isn’t dissolvable in water and instead, pushes through the intestinal system providing bulk to assist with excretion.
Soluble fiber
With its stationary action, soluble fiber acts to slow down (and in some cases prevent) the absorption of fat and cholesterol in the gut. In time, this can lead to a beneficial reduction in low-density lipoprotein (LDL) cholesterol. Soluble fiber is also effective at helping to stabilize blood glucose levels by slowing down the rate of carbohydrate absorption.
More recently, research has focused on the potential positive benefits of soluble, fermentable fibers like inulin, beta glucans and pectins that help to feed healthy gut bacteria. This may help to improve the body’s immunity and reduce the effects of food intolerances.
Soluble fiber is found in beans, oats, oat bran, rice bran, barley, citrus, apples, berries and peas.
Insoluble fiber
In contrast, insoluble fiber speeds up the removal of food and waste from the digestive system by acting as a bulking agent. It helps prevent constipation.
Fiber-containing foods add bulk but not calories to the diet, which may help manage satiety.
Food sources of insoluble fiber include wheat bran, whole grains, cereals, brown rice, seeds, and the skins of many fruits and vegetables.
The Daily Value (DV) for fiber is 25 grams for someone who eats a 2000-calorie diet. Most Americans eat about 15 grams of fiber a day and would benefit from choosing more fiber-containing foods. Americans would benefit by increasing fiber intake by 10 grams per day and a few subtle changes can help achieve this goal.
Small changes like the ones listed above can help you to reach your fiber goals. As you increase your dietary fiber intake, be sure to drink additional water to help prevent unpleasant, albeit temporary, gastrointestinal side effects.
Tamara Schryver, Environmental Nutrition Newsletter
