Fiber is edible but is not digested like most other dietary material. This substance comes in two forms: insoluble or soluble. You do not derive any significant nutrients from either fiber type. Dietary fiber is important, however, as your digestive system needs it for healthy bowel movements and constipation prevention. Each type of fiber moves through the digestive tract differently.
Definition
Fiber only comes from plants; there is no bulk in meat or animal products such as milk and eggs, according to Children's Hospital Boston. Not all plant material is fibrous. The highest fiber concentration is present in stems, seeds, peels and husks of fruits, vegetables and grains. Legumes and nuts are also high-fiber foods. Certain herbs, such as psyllium, also pass through your digestive tract as fiber.
Insoluble Fiber
Fiber is not digested for nutrients in your digestive tract, but bacteria in the lower part of your intestines metabolizes some of the bulk. Insoluble fiber retains its structure during its journey through your intestines and moves food through more quickly, MedlinePlus says. Your stool has more bulk and is softer and moister when you eat insoluble fiber, warding off constipation. Insoluble fiber comes from whole grains, vegetables and wheat bran. Make most of your fiber intake insoluble if your main concern is digestive benefits.
Soluble Fiber
Soluble fiber does not move through the digestive tract intact. It is absorbent so it blends with water in the digestive tract and becomes a jelly. This fiber types moves more slowly through your digestive tract than the insoluble type, according to MedlinePlus. You get soluble fiber from psyllium and foods such as vegetables, fruits, nuts, peas, barley, lentils, oat bran and peas. This fiber stabilizes blood sugar and brings down your blood cholesterol level. Eat more soluble fiber if you need to lower your cholesterol, have diabetes or wish to prevent it.
Considerations
Fruits, vegetables and other fibrous foods lose much of their roughage if you prepare them in certain ways. For example, peeling vegetables and fruits, removing the seeds, crushing them, drying them or making them into juice removes a high percentage of the fiber. Canning, freezing and normal cooking does not lower fiber content, although the best way to get maximum bulk is to eat raw items, including the peels, and to select whole grain products rather than processed versions. For example, choose wheat bread and whole grain flour instead of white.
Amount
You need a daily minimum of fibrous foods to get digestive benefits. Children's Hospital Boston recommends between 20 and 35 grams, although more is acceptable if you build yourself up to it gradually. Adding large amounts of fiber to your diet too quickly causes digestive tract problems like diarrhea and gas. Focus on the fiber type that offers the benefits in which you are most interested. Drink a minimum of 64 ounces of water every day. MayoClinic.com recommends that much water for everyone, and getting enough liquid is especially necessary with a high fiber diet to prevent constipation.
References
- Children's Hospital Boston; Facts About Fiber; June 2003
- Colorado State University Extension; Dietary Fiber; J. Anderson et. al.; December 2010
- MayoClinic.com; Water, How Much Should You Drink Every Day?; April 2010
- MedlinePlus; Blond Psyllium; July 2011
- MedlinePlus; Soluble vs. Insoluble Fiber; July 2010
- AskDrSears.com: What is Fiber?
- Nutrition Diva; What is the Difference Between Soluble and Insoluble Fiber?; May 2010; Monica Reinagel
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