Dietary Fiber

Dietary fiber, dietary fibre, or sometimes roughage and ruffage is the indigestible portion of plant foods having two main components:

  • soluble (may be prebiotic and/or viscous) fiber that is readily fermented in the colon into gases and physiologically active byproducts, and
  • insoluble fiber (may be metabolically inert and provide bulking or metabolically fermented in the large intestine as a prebiotic fiber). Bulking fibers absorb water as they move through the digestive system, easing defecation. Fermentable insoluble fibers mildly promote regularity, although not to the exent that bulking fibers do, but they can be readily fermented in the colon into gases and physiologically active byproducts.

Dietary fibers can act by changing the nature of the contents of the gastrointestinal tract and by changing how other nutrients and chemicals are absorbed. Some types of soluble fiber absorb water to become a gelatinous, viscous substance and is fermented by bacteria in the digestive tract. Some types of insoluble fiber have bulking action and is not fermented. Lignin, a major dietary insoluble fiber source, may alter the rate and metabolism of soluble fibers. Other types of insoluble fiber, notably resistant starch, are fully fermented.

Chemically, dietary fiber consists of non-starch polysaccharides such as arabinoxylans, cellulose, and many other plant components such as resistant starch, resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans, and oligosaccharides. A novel position has been adopted by the US Department of Agriculture to include functional fibers as isolated fiber sources that may be included in the diet. The term "fiber" is something of a misnomer, since many types of so-called dietary fiber are not actually fibrous.

Food sources of dietary fiber are often divided according to whether they provide (predominantly) soluble or insoluble fiber. Plant foods contain both types of fiber in varying degrees, according to the plant's characteristics.

Advantages of consuming fiber are the production of healthful compounds during the fermentation of soluble fiber, and insoluble fiber's ability (via its passive hygroscopic properties) to increase bulk, soften stool, and shorten transit time through the intestinal tract.

Disadvantages of a diet high in fiber is the potential for significant intestinal gas production and bloating. Constipation can occur if insufficient fluid is consumed with a high-fiber diet.

Read more about Dietary FiberDefinition of Dietary Fiber, Mechanism, Effects of Fiber Intake, Dietary Fiber and Obesity, Guidelines On Fiber Intake, Fiber and Calories, Soluble Fiber Fermentation, Short-chain Fatty Acids, FDA-approved Health Claims, Potential Longevity

Other articles related to "dietary fiber, fiber":

Dietary Fiber - Potential Longevity
... ages 50 to 71 for nine years found that the highest consumers of fiber were 22% less likely to die over this period ... heart disease, adequate consumption of fiber-containing foods, especially grains, also appeared to reduce the incidence of infectious and respiratory illnesses, and, particularly among males, lowered the risk of ...
Metamucil - Potential Side Effects
... products, such as Metamucil, are sometimes used as a source of dietary fiber, the intake of dietary fiber could hinder the absorption of vitamins ... Dietary fiber helps the gastrointestinal tract absorb excess water and remove food wastes, but an excessively high intake of dietary fiber will also negatively ... Taking a fiber supplement can decrease the absorption of minerals by decreasing the transit time, lowering the concentration of minerals by accumulating more fecal matter, and can also cause the minerals to become ...
Animal Nutrition - Fat - Fiber
... Dietary fiber is a carbohydrate (or a polysaccharide) that is incompletely absorbed in humans and in some animals ... Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to disassemble it ... There are two subcategories soluble and insoluble fiber ...
Raspberries - Uses - Fruits - Nutrients and Phytochemicals
... g (3.5 oz) Energy 220 kJ (53 kcal) Carbohydrates 11.94 g - Sugars 4.42 g - Dietary fiber 6.5 g Fat 0.65 g Protein 1.2 g Thiamine (vit ... nutritional value, as it increases the proportion of dietary fiber, which is among the highest known in whole foods, up to 20% fiber per total weight. 32 mg per serving of 1 cup (about 54% daily value), manganese (about 41% daily value) and dietary fiber (about 32% daily value) ...

Famous quotes containing the word fiber:

    I taught school in the early days of my manhood and I think I know something about mothers. There is a thread of aspiration that runs strong in them. It is the fiber that has formed the most unselfish creatures who inhabit this earth. They want three things only; for their children to be fed, to be healthy, and to make the most of themselves.
    Lyndon Baines Johnson (1908–1973)