Dietary fiber or Dietary fibre or sometimes roughage is the indigestible portion of plant foods having two main components:
soluble (prebiotic, viscous) fiber that is readily fermented in the colon into gases and physiologically active byproducts, and
insoluble fiber that is metabolically inert, absorbing water throughout the digestive system and easing defecation.[1]
It acts by changing the nature of the contents of the gastrointestinal tract, and by changing how other nutrients and chemicals are absorbed.[2] Soluble fiber absorbs water to become a gelatinous, viscous substance and is fermented by bacteria in the digestive tract. Insoluble fiber has bulking action and is not fermented,[3] although a major dietary insoluble fiber source, lignin, may alter the fate and metabolism of soluble fibers.[1]
Chemically, dietary fiber consists of non-starch polysaccharides such as arabinoxylans, cellulose and many other plant components such as resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans and oligosaccharides.[1] 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.[1] The term "fiber" is something of a misnomer, since many types of so-called dietary fiber are not fibers at all.
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 salubrious compounds during the fermentation of soluble fiber, and insoluble fiber's ability (via its passive hydrophilic properties) to increase bulk, soften stool and shorten transit time through the intestinal tract.
Sources of fiber
Dietary fiber is found in plants. While all plants contain some fiber, plants with high fiber concentrations are generally the most practical source.
Fiber-rich plants can be eaten directly. Or, alternatively, they can be used to make supplements and fiber-rich processed foods.
The American Dietetic Association (ADA) recommends consuming a variety of fiber-rich foods.
[edit] Plant sources of fiber
Legumes such as soybeans contain dietary fibers.Some plants contain significant amounts of soluble and insoluble fiber. For example plums (or prunes) have a thick skin covering a juicy pulp. The plum's skin is an example of an insoluble fiber source, whereas soluble fiber sources are inside the pulp.[4]
Soluble fiber is found in varying quantities in all plant foods, including:
legumes (peas, soybeans, and other beans)
oats, rye, chia, and barley
some fruits and fruit juices (including prune juice, plums, berries, bananas, and the insides of apples and pears)
certain vegetables such as broccoli, carrots, and Jerusalem artichokes
root tubers and root vegetables such as sweet potatoes and onions (skins of these are sources of insoluble fiber)
psyllium seed husk (a mucilage soluble fiber).
Sources of insoluble fiber include:
whole grain foods
wheat and corn bran
nuts and seeds
potato skins
flax seed
lignans
vegetables such as green beans, cauliflower, zucchini (courgette), celery, and nopal
some fruits including avocado, and bananas
the skins of some fruits, including tomatoes
http://en.wikipedia.org/wiki/Dietary_fiber
soluble (prebiotic, viscous) fiber that is readily fermented in the colon into gases and physiologically active byproducts, and
insoluble fiber that is metabolically inert, absorbing water throughout the digestive system and easing defecation.[1]
It acts by changing the nature of the contents of the gastrointestinal tract, and by changing how other nutrients and chemicals are absorbed.[2] Soluble fiber absorbs water to become a gelatinous, viscous substance and is fermented by bacteria in the digestive tract. Insoluble fiber has bulking action and is not fermented,[3] although a major dietary insoluble fiber source, lignin, may alter the fate and metabolism of soluble fibers.[1]
Chemically, dietary fiber consists of non-starch polysaccharides such as arabinoxylans, cellulose and many other plant components such as resistant dextrins, inulin, lignin, waxes, chitins, pectins, beta-glucans and oligosaccharides.[1] 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.[1] The term "fiber" is something of a misnomer, since many types of so-called dietary fiber are not fibers at all.
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 salubrious compounds during the fermentation of soluble fiber, and insoluble fiber's ability (via its passive hydrophilic properties) to increase bulk, soften stool and shorten transit time through the intestinal tract.
Sources of fiber
Dietary fiber is found in plants. While all plants contain some fiber, plants with high fiber concentrations are generally the most practical source.
Fiber-rich plants can be eaten directly. Or, alternatively, they can be used to make supplements and fiber-rich processed foods.
The American Dietetic Association (ADA) recommends consuming a variety of fiber-rich foods.
[edit] Plant sources of fiber
Legumes such as soybeans contain dietary fibers.Some plants contain significant amounts of soluble and insoluble fiber. For example plums (or prunes) have a thick skin covering a juicy pulp. The plum's skin is an example of an insoluble fiber source, whereas soluble fiber sources are inside the pulp.[4]
Soluble fiber is found in varying quantities in all plant foods, including:
legumes (peas, soybeans, and other beans)
oats, rye, chia, and barley
some fruits and fruit juices (including prune juice, plums, berries, bananas, and the insides of apples and pears)
certain vegetables such as broccoli, carrots, and Jerusalem artichokes
root tubers and root vegetables such as sweet potatoes and onions (skins of these are sources of insoluble fiber)
psyllium seed husk (a mucilage soluble fiber).
Sources of insoluble fiber include:
whole grain foods
wheat and corn bran
nuts and seeds
potato skins
flax seed
lignans
vegetables such as green beans, cauliflower, zucchini (courgette), celery, and nopal
some fruits including avocado, and bananas
the skins of some fruits, including tomatoes
http://en.wikipedia.org/wiki/Dietary_fiber
