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Division o Agricultural Sciences and Natural Resources Oklahoma State University

T-3138

Janice R Hermann, Ph.D., RD/LDNutrition Education Specialist

What are Dietary FibersMost dietary bers are carbohydrates, but they are not

digestible. The human body lacks the enzymes needed tobreakdown dietary bers or absorption. As a result, dietarybers reach the lower intestine intact. Dietary bers includemany substances such as cellulose, hemicellulose, gums,pectins, lignins, mucilages, and tannins.

In general, dietary bers are divided into two basic types:insoluble bers and soluble bers. Both types o ber areimportant or good health. Insoluble bers are ound in oodssuch as wheat bran, corn bran, whole grain breads and cereals,and vegetables. Insoluble bers help with intestinal unction.Insoluble bers absorb water and swell up in the intestine,resulting in a larger soter stool that moves through the intestineeasier and aster. Soluble bers are ound in some ruits, oats,barley, and legumes. Soluble bers orm a gel when water isadded to them. This contributes to a eeling o ullness in thestomach. Soluble bers slow down the rate ood leaves thestomach and some nutrients are absorbed. Soluble bers alsohelp control blood glucose and blood cholesterol levels.

Health Benefts o Dietary FibersDietary bers are important or good health. Dietary bers

provide health benets or many conditions including consti-pation, diverticular disease, colon cancer, heart disease, and

diabetes. However, dietary bers are only one actor involvedin these conditions. In addition to providing dietary bers,oods rich in complex carbohydrates tend to be low in at andcontribute many other compounds such as vitamins, minerals,and phytochemicals that also may provide health benets.

Digestive System

Insoluble bers provide many health benets in the diges-tive tract. Insoluble bers absorb water resulting in a larger,soter stool that is aster and easier to eliminate, which canhelp relieve constipation.

Diverticular Disease

Diverticular disease is where there are protrusions or out-

pouches in the wall o the colon. These pouches are believedto develop rom excessive pressure, which weakens the wallo the colon. In many cases, there are no obvious symptoms,but in some people the diverticula become infamed and pain-ul. Insoluble bers may help prevent diverticular disease byabsorbing water making a larger, soter stool that requiresless pressure to move through the digestive system.

Colon Cancer

Both insoluble and soluble bers may protect againstcolon cancer. Insoluble bers absorb water making a larger,

soter stool. A larger stool can help dilute potential cancercausing substances in the intestine. Since a larger, soterstool moves through the intestine aster, the colon is exposedto any cancer causing substance or less time. Bile acids arereleased into the intestine to help with at digestion. Bile acidscan be converted into potential cancer causing substances inthe intestine. Soluble bers can bind bile acids and increasetheir excretion.

Heart Disease

Soluble bers may have a role in lowering blood choles-terol. As mentioned, soluble bers can bind to bile acids andincrease their excretion. With ewer bile acids in the intestine,less at is absorbed. Also by increasing bile acid excretion,the liver must use its cholesterol to make new bile acids.

Diabetes

Soluble bers may have a avorable eect on bloodglucose. Soluble bers decrease the rate at which ood isreleased rom the stomach and delays glucose absorptioninto the blood. This may help prevent wide swings in bloodglucose throughout the day.

How much Dietary FiberIn 2002, the National Research Council set Dietary Reer-

ence Intakes (DRIs) or the rst time or dietary ber. AdequateIntakes (AI) or dietary ber were based on 14 grams dietaryber per 1,000 calories.

Dietary ber can bind some minerals and decreasetheir absorption. However, i mineral intake is adequate arecommended dietary ber intake will not compromise min-eral balance. Fiber intake is like all nutrients in that more isnot always better. The importance o consuming a diet thatprovides a variety o nutrients is the key.

Fiber on the Food LabelThe Nutrition Facts Panel on ood labels lists the number

o grams o ber per serving o ood. The Nutrition Facts Panelalso lists the percent Daily Value one serving provides or berbased on a 2,000 calorie reerence diet. The FDA set a DailyValue on ood labels or ber at 25 grams or a 2,000 caloriediet. The ollowing terms are used on ood labels to describethe ber content o oods.

High source o ber is 5 grams or more ber per serving Good source o ber is 2.5 to 4.9 grams o ber per serving

Dietary Fiber

Oklahoma Cooperative Extension Fact Sheetsare also available on our website at:

http://osuacts.okstate.edu

Oklahoma Cooperative Extension Service

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Food Sources o Dietary FibersDietary bers come rom plant oods. The best sources

o dietary ber are whole grain breads and cereals, ruitsand vegetables, legumes, nuts and seeds. Foods are the

best source o dietary ber. Foods provide both soluble andinsoluble ber. In addition, ood sources o ber can be spacedout over the whole day.

You can get enough dietary ber without using ber supple-ments by choosing oods high in ber and ollowing the USDAMyPyramid recommendations o 2.5 cups o vegetables, 2cups o ruit, and 6 oz. o grains or a reerence 2,000 caloriediet. Cooking, processing, and removing peels can lower theber content in oods. The ollowing tips can help you makehigher ber selections through the UDSDA MyPyramid oodgroups.

Healthy Choices to Increase Fiber

through the USDA MyPyramid

Grain Group

To increase the ber content in breads look or whole-grainbreads with whole wheat four, stone-ground wholewheat four or 100 percent whole wheat four as therst ingredient.

To increase the ber content in cereals look or whole-grain wheat, whole-grain oats or whole-grain rice asthe rst ingredient.

Brown rice is higher in ber than rened white rice. Experiment with dierent ood such as couscous, barley,

bulgur, quinoa and kasha in salads, soups and casserolesto increase ber.

Fruit and Vegetable Groups Fruits are naturally high in ber. Fresh ruits are higher

in ber than rozen or canned. Peels and seeds in ruitsincrease ber.

Vegetables are also naturally high in ber. To keep theber content o vegetables high, try eating them raw orsteam just until tender. Leaving the skins on vegetablescan also increase ber.

Add dried ruits to cereal, muns and quick breads toincrease ber.

Meat and Beans Group

Dried beans and peas are low in at and an excellentsource o ber, vitamins and minerals. Add beans, peasand lentils to soups, stews, salads and rice dishes.

Nuts are a good source o ber but are also high in at.

Guidelines or Increasing Dietary FiberIt is important to increase dietary ber intake slowly. In-

creasing dietary ber intake too ast may cause unpleasantside eects such as bloating and excessive gas. Since berabsorbs water it also is important to drink plenty o fuids when

increasing dietary ber. Include at least six to eight cups o fuideach day. Also, try to spread out high ber oods throughoutthe day.

ReerencesUnited States Department o Agriculture. MyPyramid: Steps

to a Healthier You. Accessed at www.mypyramid.gov,

2005.

United States Department o Agriculture. 2005 Dietary

Guidelines or Americans. Accessed at: www.health.gov/

dietaryguidelines/dga2005.

Whitney, E.N. & Roles, S.R. Understanding Nutrition, 10th

ed. 2005. Thomson/Wadsworth Publishing Co., Belmont,

CA.

Adequate Intakes For Dietary Fiber (grams/day)

Age Male Female

0 to 6 months Not Determined Not Determined

7 to 12 months Not Determined Not Determined

1 to 3 years 19 19

4 to 8 years 25 25

9 to 13 years 31 26

14 to 18 years 38 26

19 to 30 years 38 2531 to 50 years 38 25

51 to 70 years 30 21

71 years and older 30 21

Pregnancy < 19 years - 28

Pregnancy 19-50 years - 28

Lactation < 19 years - 29

Lactation 19 - 50 years - 29

Oklahoma State University, in compliance with Title VI and VII o the Civil Rights Act o 1964, Executive Order 11246 as amended, Title IX o the Education Amendments o 1972, Americanswith Disabilities Act o 1990, and other ederal laws and regulations, does not discriminate on the basis o race, color, national origin, gender, age, religion, disability, or status as a veteran inany o its policies, practices, or procedures. This includes but is not limited to admissions, employment, nancial aid, and educational services.

Issued in urtherance o Cooperative Extension work, acts o May 8 and June 30, 1914, in cooperation with the U.S. Department o Agriculture, Robert E. Whitson, Director o Cooperative Exten-sion Service, Oklahoma State University, Stillwater, Oklahoma. This publication is printed and issued by Oklahoma State University as authorized by the Vice President, Dean, and Director othe Division o Agricultural Sciences and Natural Resources and has been prepared and distributed at a cost o 20 cents per copy. 0607