Fiber is the part of a plant your body cannot digest. The body digests the three macronutrients -- carbohydrates, fat and protein -- and converts them to energy, but fiber simply passes through the body undigested. Fiber, however, plays an important part in your health. Insoluble fiber helps you have regular bowel movements.
Types of Fiber
Fiber, often called bulk or roughage, is categorized as soluble or insoluble. Soluble fiber dissolves in water, but insoluble fiber does not. Neither type of fiber contains calories; they pass through your body undigested. Since soluble fiber dissolves in water, it turns to a gel-like substance and slows the digestion process, which makes you feel fuller. Soluble fiber lowers cholesterol and helps control the sugar levels in your blood.
Insoluble Fiber
Insoluble fiber does not always receive the good press soluble fiber does, because its benefits are not as exciting. Insoluble fiber adds bulk to your stool and helps waste pass quickly through your colon. This reduces constipation and keeps your bowel movements more regular. Insoluble fiber also helps good bacteria, or gut flora, grow in your colon. Gut flora increases your body's ability to absorb nutrients from food and boosts your body's immune function by stimulating the synthesis of antibacterial proteins.
Sources of Insoluble Fiber
The major sources of insoluble fiber are vegetables, fruits, nuts and whole grains. Bran, which is the hard, outer layer of a grain, is an excellent source of insoluble fiber. To make sure you are eating bran, select grain products that are 100 percent whole grain. Some fruits are high in insoluble fiber, with raspberries, strawberries and apples topping the list. Okra, peas and beans are also good sources of insoluble fiber.
Considerations
Eating a high-fiber diet has many benefits. It reduces your risk for diverticulitis, which is a painful condition of the colon, and hemorrhoids. If you currently do not eat much fiber, increase your consumption slowly over a few weeks. Otherwise, you may experience bloating and abdominal discomfort. The Institute of Medicine recommends males consume between 30 and 38 grams and females between 21 and 26 grams of fiber per day. The institute does not break down the recommendations by fiber type.
References
- Mayo Clinic; Dietary Fiber: Essential for a Healthy Diet; November 2009
- University of Maryland Medical Center; Soluble Vs. Insoluble Fiber - Overview; August 2008
- Harvard University; Fiber Content of Foods in Common Portions; May 2004
- Bastyr University; Do We Really Need Insoluble Fiber?; Natalie Libby and Debra A. Boutin, MS, RD
- Institute of Medicine: Dietary Reference Intakes
- Kenyon College; Intestinal Microflora and Antibiotic Resistance; August 2010
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