fiber

(fī'bər)
n.

1. A slender, elongated, threadlike object or structure.
2. Botany. One of the elongated, thick-walled cells that give strength and support to plant tissue.
3. Anatomy.
   1. Any of the filaments constituting the extracellular matrix of connective tissue.
   2. Any of various elongated cells or threadlike structures, especially a muscle fiber or a nerve fiber.
4. 1. A natural or synthetic filament, as of cotton or nylon, capable of being spun into yarn.
   2. Material made of such filaments.
5. 1. Something that provides substance or texture.
   2. Essential character: "stirred the deeper fibers of my nature" (Oscar Wilde).
   3. Basic strength or toughness; fortitude: lacking in moral fiber.
6. Coarse, indigestible plant matter, consisting primarily of polysaccharides such as cellulose, that when eaten stimulates intestinal peristalsis. Also called bulk, roughage.

[French fibre, from Old French, from Latin fibra.]

fibered fi'bered adj.

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noun

1. A very fine continuous strand: fibril, filament, thread. See thing.
2. A distinctive, complex underlying pattern or structure: contexture, fabric, texture, warp and woof, web. See be.
3. Moral or ethical strength: character, honesty, integrity, principle. See strong/weak.

Denis Burkitt (1911–1993), a British surgeon and medical researcher, is usually credited with popularizing the idea that dietary fiber may protect against the development of chronic diseases such as diabetes, hypercholesterolemia, heart disease, diverticular disease, and colon cancer that are prevalent in Western countries. Writing in the 1970s and 1980s, Burkitt described the relationship between large stools, which reflect a high intake of plant foods rich in dietary fiber, and a lack of "Western diseases," as he called them.

Dietary fiber is plant cell material that resists digestion by the endogenous enzymes of humans. It is not really an accurate term, as many of its components are not fibrous. Gums and mucilages, for example, are classified as dietary fiber because mammalian enzymes or secretions do not digest them. Only one component of dietary fiber, cellulose, is truly fibrous; yet "dietary fiber" is the accepted term for describing the roughage in the human diet.

Dietary fiber is found only in plant products, including fruits, vegetables, nuts, and grains. The most concentrated sources of dietary fiber are the bran layers of grains, such as wheat bran. Because of their higher water content, fruits and vegetables provide less dietary fiber per gram of ingested material than grains and cereals.

Recommendations for adult dietary fiber intake generally fall in the range of 20 to 35 grams per day. For children, the general rule is to add five to a child's age to determine the number of grams of fiber to be consumed daily. Thus, a ten-year-old child should consume 15 grams of dietary fiber a day. Usual intakes of dietary fiber in the United States average only 11 grams per day, so few people get the recommended amount. Most of the popular foods Americans consume contain little dietary fiber. For example, most servings of grains, fruits, and vegetables contain 1 to 3 grams of dietary fiber. Thus, to get the recommended amounts of dietary fiber one would need to consume at least ten servings of fiber-containing foods per day. Dietary fiber content of foods is listed on the Nutrition Facts panel on food packages. Foods particularly high in dietary fiber include bran cereals, which contain up to 13 grams of dietary fiber per serving, and beans and legumes, which contain more than 5 grams of dietary fiber per serving.

Several epidemiologic studies indicate that a high intake of dietary fiber protects against most chronic diseases. This is true even when confounding variables such as fat and calorie intake are accounted for. Dietary fiber may protect against large bowel cancer by enhancing the environment of the large intestine. Dietary fiber escapes digestion in the small intestine and is fermented in the large intestine by intestinal microflora. This fermentation yields short-chain fatty acids and gases. Short-chain fatty acids, including butyrate and propionate, have interesting physiological properties. Butyrate is a preferred gut fuel for the cells in the colon. Additionally, propionate may be involved in the cholesterol-lowering effects of certain dietary fiber. Dietary fiber fermentation may also enhance the number of beneficial microflora, such as bifidobacteria and lactobacillus. However, two recent large intervention studies did not find any protection in polyp prevention, which has led to questions about whether fiber should be recommended to prevent colon cancer (Goodlad, 2001).

Dietary fiber is an accepted therapy for gastrointestinal disorders such as constipation and diarrhea, and is often consumed as bulk laxatives or high-fiber breakfast cereals. Fiber may also protect against other cancers. International comparisons show an inverse correlation between breast cancer death rates and consumption of fiber-rich foods.

Dietary fiber has also been shown to be effective in reducing serum cholesterol, and it may decrease the risk of coronary heart disease by decreasing serum lipids, lowering blood pressure, improving glucose metabolism, and aiding in weight control. Soluble fibers appear to be the most effective in lowering serum cholesterol. The U.S. Food and Drug Administration (FDA) has accepted health claims for the cholesterol-lowering ability of oat bran and psyllium fiber. A significant reduction in serum cholesterol by soluble fiber was observed in sixty-eight of the seventy-seven human studies reviewed in a meta-analysis. Often, soluble fibers also decrease low-density lipoproteins (LDL) while maintaining high-density lipoproteins (HDL). Multiple mechanisms appear to be involved in the hypocholesterolemic response, and mechanisms for lowering cholesterol may vary considerably among the various sources of dietary fiber.

Some clinical research suggests that dietary fiber may also play a role in improving blood-sugar control in diabetes. Dietary fiber, especially soluble fiber, can delay glucose absorption and reduce insulin requirements in both insulin-dependent and non-insulin-dependent diabetes mellitus. Obese persons with diabetes often respond to a high-fiber diet with weight loss and decreased insulin requirements.

The best way to get dietary fiber in the diet is to consume a wide range of grains, legumes, fruits, and vegetables. Concentrated fiber sources such as bulk laxatives, fiber supplements, and foods fortified with fiber may be useful in the prevention and treatment of bowel disorders and as lipid-lowering therapies. Fiber supplements should be taken under medical supervision, since bowel obstructions, dehydration, and other medical contra-indicators have been reported with their use.

(SEE ALSO: Chronic Illness; Coronary Artery Disease; Foods and Diets; HDL Cholesterol; LDL Cholesterol; Nutrition)

Bibliography

Burkitt, D. P.; Walker, A. R.; and Painter, N. S. (1972). "Effect of Dietary Fiber on Stools and the Transit-Times, and its Role in the Causation of Disease." Lancet 2(7792):1408–1412.

Goodlad, R. A. (2001). "Dietary Fiber and Risk of Colorectal Cancer." GUT 48:587–589.

Schatzkin, A.; Lanza, E.; Corle, D.; Lance, P.; Cann, B.; Shike, M.; Weissfeld, J.; Burt, R.; Cooper, M. R.; Kikendall, J. W.; Cahill, J.; and the Polyp Prevention Trial Study Group (2000). "Lack of Effect of a Low-Fat, High-Fiber Diet on the Recurrence of Colorectal Adenomas." New England Journal of Medicine 342:1149–1155.

— JOANNE SLAVIN

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Although Western tradition ranks clothing among the basic needs along with food and shelter, the members of some human societies in the recent past wore no clothing, and many societies today wear very little. Climate is not the deciding factor for nakedness, as societies known to use the least amount of clothing, the Fuegan and Tasmanian of 200 years ago, lived on islands with notoriously bad weather. In Europe, however, clothing is known from very early times. Small statues depict clothing as early as 15,000 bce. This clothing is thought to be of animal skins, but linen cloth made by weaving existed at least as early as 6000 bce. In any case, animal skins are not the right shape or size for clothing and need to be sewn together with fiber of some sort. While thin strips of skin have been used as fibers, the Ice Man of 3300 bce used animal sinews in some places and grass in others.

Although the earliest recorded evidence of the use of fiber involves flax -- linen is fiber from the flax plant -- ambiguous evidence suggests that wool from sheep or goats was employed for cloth by that time as well. Sheep and goats were among the first domesticated animals; in the New World, llamas and alpacas, which also produce wool, were also domesticated early.

In warmer climates of both the Old and New worlds, cotton became the most common plant fiber from early times. By the 18th century ce, cotton was shipped all over the world. Introduction of new ways of processing cotton was a hallmark of the Industrial Revolution.

Humans are not the only animals to use fiber. Birds have long used animal hair and plant fibers for nest building. They also anticipated humans in the discovery of the utility of silk, a chemical fiber produced by spiders and caterpillars. Most birds prefer spider silk, some of which forms a micro-Velcro and some of which has adhesives attached. People in China discovered that the caterpillar of the silkworm moth produces the longest silk fibers in nature, some 900 m (3000 ft) long. Shiny silk was seen from the first as superior to animal hair or plant fibers. During the Chinese's virtual monopoly of hundreds of years, trade in silk became the strand that held eastern Asia to the West along the famous Silk Road.

Silk begins as a liquid that is extruded though a tiny opening; it hardens into a solid in the air. As early as the 17th century, inventors recognized that this process could be imitated by a machine if the right liquid were found. Some early attempts used gums or other natural plant products. Chemists in the 19th century perceived that cellulose from the breakdown of wood or some variation on it would do the trick. At least a half dozen different versions of such artificial silks emerged, the best of which we now call rayon. In the 20th century, the same idea was used with a different class of chemicals, the polymers. In bulk, the polymers are plastics, but as fibers they are nylon, Dacron, and polyester. For many purposes, the artificial fibers are better (wrinkle-free cloth is often cited as the greatest boon), but natural fibers continue to excel for others.

Fiber, which is found in all plant-based foods, is composed of a group of compounds that makes up the framework of plants. Although fiber cannot be digested, it is an essential nutrient for good health. The health benefits of a diet rich in fiber include lower cholesterol and a reduced risk of heart disease and certain cancers. Also referred to as roughage, fiber is made up of many compounds, mostly carbohydrates. It can be found in a variety of foods, including wheat, potatoes, and certain fruits and vegetables. Although the recommended amount of fiber is 20 to 35 grams a day, the average American consumes only 12 to 15 grams on a daily basis. Asians, on average, consume three times as much fiber as Americans do.

Types of Fiber
Complex carbohydrates, which are a major source of energy for the body, are comprised of two main classes: starch, which is digestible, and fiber, which is generally not digestible. There are also two kinds of fiber: insoluble and soluble. Insoluble fiber, found in wheat bran and some fruits and vegetables, cannot be dissolved in water. This type of fiber is made up of cellulose and hemicellulose, substances that offer rigidity to plant material (e.g., the peels and skins of fruits and vegetables, wood, stems, and the outer coverings of nuts, seeds, and grains). Insoluble fiber acts as a natural laxative, giving stool the bulk necessary to move quickly through the gastrointestinal tract. In addition to preventing constipation and hemorrhoids, insoluble fiber may also reduce the risk of colon cancer by speeding the passage of food through the digestive tract.

Soluble fiber, found in beans, oats, and some fruits and vegetables, is fiber that can be dissolved in water. This type of fiber is made up of pectins, gums, and mucilages. Marie Boyle notes that, because it reduces the level of cholesterol in the blood, soluble fiber can reduce the risks of heart and artery disease and atherosclerosis. When consumed in large amounts, soluble fiber also slows glucose absorption from the small intestine, which can be helpful in treating diabetes. Finally, a diet high in fiber may also promote weight control and reduce the risk of developing obesity.

How Much Fiber Is Necessary?
According to the American Dietetic Association, the daily goal for fiber intake is between 20 and 35 grams. However, the average intake in the United States is only 12 to 15 grams. In contrast, people in China consume as much as 77 grams of fiber per day. Children also need fiber, although in different amounts than adults. For children up to age 18, the recommended daily dose (in grams) is determined by adding five to a child's age. For example, a seven-year-old child would need 12 grams of fiber a day.

Food	Amount	Fiber (g)
Whole-wheat bread	1 slice	1.6
Rye bread	1 slice	1.0
White bread	1 slice	0.6
Brown rice (cooked)	½ cup	2.4
White rice (cooked)	½ cup	0.1
Spaghetti (cooked)	½ cup	0.8
Kidney beans (cooked)	½ cup	5.8
Lima beans (cooked)	½ cup	4.9
Potato (baked)	Medium	3.8
Corn	½ cup	3.9
Spinach	½ cup	2.0
Lettuce	½ cup	0.3
Strawberries	¾ cup	2.0
Banana	Medium	2.0
Apple (with skin)	Medium	2.6
Orange	Small	1.2

SOURCE: Adapted from Edlin et al., 2002.

The recommended daily amount of fiber can be consumed by eating a diet high in fiber-rich fruits, vegetables, and whole grains. There are several ways to ensure one consumes enough fiber. First, it is important to read food labels. Although they do not distinguish between the two types of fiber, the labels of almost all foods will provide the amount of dietary fiber in each serving. Raw or slightly cooked vegetables will also provide an excellent source of fiber. However, overcooking vegetables may reduce the fiber content. Whole-grain cereals, whole-wheat bread, fresh or dried fruit, beans, rice, and salad are all good sources of fiber. The table presents the fiber content of various foods.

Problem with High-Fiber Diets
Including fiber in one's daily diet has definite benefits. However, although very uncommon, fiber has the potential to cause harm if taken in excess of 60 or 70 grams daily. "Since fiber carries water out of the body, taking too much can cause dehydration and intestinal discomfort or gas," (Boyle, p. 84). Large amounts of fiber require a high fluid intake. Therefore, as one increases fiber in the diet, water intake must also be increased. If one does not consume enough fluid, then one's stool could become very hard, resulting in difficult and painful elimination.

Fiber speeds the movement of foods through the digestive system. Since iron is mainly absorbed early during digestion, high amounts of fiber may limit the opportunity for the absorption of iron, calcium, and other nutrients. Finally, large amounts of fiber can also cause deficiencies of nutrients and energy by causing one to feel full before enough nutrients have been consumed. Children and elderly persons are especially vulnerable to these concerns, since they eat smaller portion sizes.

In conclusion, fiber is an important element of the diet and provides several health benefits. Eating balanced meals containing whole grain and fresh fruits and vegetables will ensure meeting the proper recommended allowances.

See also Cancer; Carbohydrates; Heart disease; Nutrients.

Bibliography
Boyle, Marie, A. (2001). Personal Nutrition, 4th edition. Belmont, CA: Wadsworth/Thomson Learning.
Edlin, Gordon; Golanty, Eric; and McCormick Brown, Kelli, eds. (2002). Health and Wellness, 7th edition. Sudbury, MA: Jones and Bartlett.
Wardlaw, Gordon M. (2000). Contemporary Nutrition, Issues and Insights, 4th edition. Boston: McGraw Hill.

Internet Resources
American Dietetic Association. "Health Implications of Dietary Fiber—Position of ADA." Available from http://www.eatright.com
Food and Drug Administration. "Why Is Fiber Important to Your Diet?"Available from http://www.cfsan.fda.gov
Nutrition Newsletter (1997). "China Project Monograph Named China's Best Scientific Publication." Available from http://www.nutrition.cornell.edu/news

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What is Fiber?

Fiber is found only in foods of plant origin. It occurs in the skins, seeds, leaves and roots of fruits and vegetables, and in the germ and bran layers of grains. Pectins, lignans, cellulose, gums and mucilages are all different forms of fiber found in these foods. Because humans lack the digestive enzymes to break down fiber, it passes through the digestive tract largely unchanged.

What is the Purpose of Fiber?

Depending on the type, fiber may either slow down or speed up the passage of food through the digestive tract. It contributes to stool bulk and stimulates the colon walls to contract. Foods rich in soluble fiber are often recommended to help improve blood glucose and cholesterol levels, while diets containing high amounts of insoluble fiber are known to contribute to bowel regularity and the prevention of diverticular disease. Since high-fiber diets tend to be satisfying but relatively low in calories, they are often promoted for weight management.

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One of the elongated, thick-walled cells that give strength and support to plant tissue.

n

An elongated, threadlike structure of organic tissue.

For a list of words related to fiber, see:

• Tissue, Fiber, and Integumentary System - fiber: strong, threadlike structure of protein
• Nutrition For Fitness - fiber: dietary substance, usu. cellulose, found in plants, that promotes gastrointestinal fitness
• Plastics, Paper, and Textiles - fiber: slender, threadlike structure found in vegetable tissue or made synthetically
• Fabrics and Cloth - fiber: slender, filamentous substance formed into threads for making fabric
• Fashion, Trim, and Sewing - fiber: slender, threadlike structure from which either natural or synthetic yarn is made

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See words rhyming with "fiber."

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - fiber, trævl, støbning

idioms:

• fibre optics    fiberoptik
• with every fibre of your being    med sjæl og legeme

Nederlands (Dutch)
vezel, axon/dendriet (uitlopers van zenuwcel), kracht/kwaliteit, kenmerkende structuur, vezelachtige structuur, karakter

Français (French)
n. - fibre, (Tex) fibre, fibres, cellulose végétale, (Bot) fibre, (Physiol) fibre, (fig) courage

idioms:

• fibre optics    fibres optiques
• with every fibre of one's being    de tout son être

Deutsch (German)
n. - Faser, Faserstoff, Charakter

idioms:

• fibre optics    Faseroptik
• with every fibre of one's being    sehr intensiv

Ελληνική (Greek)
n. - ίνα, νημάτιο, (μτφ.) ιδιοσυστασία, χαρακτήρας

idioms:

• fibre optics    οπτικές ίνες
• with every fibre of your being    με κάθε ίνα της ύπαρξής σου

Italiano (Italian)
fibra

idioms:

• fibre optics    fibre ottiche
• with every fibre of your being    con tutte le tue forze

Português (Portuguese)
n. - fibra (f)

idioms:

• fibre optics    fibra (f) ótica
• with every fibre of your being    profundamente

Русский (Russian)
волокно, склад характера, устойчивость, грубая пища

idioms:

• fibre optics    волоконная оптика
• with every fibre of your being    всеми фибрами души

Español (Spanish)
n. - fibra, filamento

idioms:

• fibre optics    fibra óptica
• with every fibre of one's being    con toda el alma

Svenska (Swedish)
n. - fiber, fibermassa, rottråd, struktur, natur (bildl.)

中文（简体）(Chinese (Simplified))
纤维, 纤维制品, 构造

idioms:

• fibre optics    纤维光学
• with every fibre of your being    竭尽全力

中文（繁體）(Chinese (Traditional))
n. - 纖維, 纖維製品, 構造

idioms:

• fibre optics    纖維光學
• with every fibre of your being    竭盡全力

한국어 (Korean)
n. - 섬유, 성격, 강도

idioms:

• with every fibre of your being    학문적으로 유용한

日本語 (Japanese)
n. - 繊維, 繊維製品, 繊維質, 性質, 素質, ひげ根, 強み

idioms:

• fibre optics    繊維光学

العربيه (Arabic)
‏(الاسم) ليف , نسيج‏

עברית (Hebrew)
n. - ‮סיב, אופי, מבנה, חוט, ליף‬

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