Dietary Fiber

In 1985 and 1986, almost one-half of dietary fiber in the diets of women was supplied by fruits and vegetables and another 35 percent by grain products. Dietary fiber is not found in animal products, such as milk and meats. The fiber shown in the chart as coming from these groups was contributed by grain products or vegetables added to them. Even foods that contain small amounts of dietary fiber can make an important contribution to an individual's diet if these foods are eaten often or in large amounts.

WHAT IS DIETARY FIBER?

Also called: Bulk, Roughage

Fiber is a substance in plants. Dietary fiber is the kind you eat. It is in fruits, vegetables and grains. It is the part of the plant that your body can't digest. Yet it is an important part of a healthy diet.

You can get fiber from whole grains, beans, nuts, fruits and vegetables. You should add fiber to your diet slowly. Increasing dietary fiber too quickly can lead to gas, bloating and cramps.

There are two major kinds of dietary fiber - insoluble (cellulose, hemicellulose, lignin) and soluble (gums, mucilages, pectins). Insoluble fiber is most frequently found in whole-grain products such as whole-wheat bread. Foods containing soluble fibers are fruits, vegetables, dry beans and peas, and some cereals such as oats.

WHY DO WE NEED DIETARY FIBER?

Insoluble fiber promotes normal elimination by providing bulk for stool formation and thus hastening the passage of the stool through the colon. Fiber is important for proper bowel function. It helps reduce constipation and diverticulosis. Insoluble fiber also helps to satisfy appetite by creating a full feeling, helping you control your weight. Some studies indicate that soluble fibers may play a role in reducing the level of cholesterol in the blood.

See Bulking Up Fiber's Healthful Reputation for more health information about fiber.

HOW MUCH DIETARY FIBER DO AMERICANS EAT?

According to recent USDA surveys, the average intake of dietary fiber by women 19 to 50 years of age is about 12 grams. Intake by men of the same age is about 17 grams.

HOW CAN WE GET ENOUGH DIETARY FIBER?

Eating a variety of foods that contain dietary fiber is the best way to get an adequate amount. Healthy individuals who eat a balanced diet rarely need supplements. The list of foods will help you select those that are significant sources of dietary fiber as you follow the Dietary Guidelines. The list of sources was derived from the same nutritive value of foods tables used to analyze information for recent food consumption surveys of the U.S. Department of Agriculture, Human Nutrition Information Service.

Choose foods that name one of the following whole-grain ingredients first on the label’s ingredient list:

• “brown rice”
• “bulgur”
• “graham flour”
• “oatmeal”
• “whole-grain corn”
• “whole oats”
• “whole rye”
• “whole wheat”
• “wild rice”

Foods labeled with the words “multi-grain,” “stone-ground,” “100% wheat,” “cracked wheat,” “seven-grain,” or “bran” are usually not whole-grain products.

Color is not an indication of a whole grain. Bread can be brown because of molasses or other added ingredients. Read the ingredient list to see if it is a whole grain.

Supplements:

If it is difficult to eat the required amounts of fruits and vegetables, is there any harm in taking a fiber supplement every day instead?

There's no evidence that long-term use of fiber supplements — such as Metamucil, Konsyl or Citrucel — is harmful. Doctors often recommend daily fiber supplements for people with certain digestive disorders, such as irritable bowel or chronic constipation.

Fiber supplements make stool soft, which can ease constipation. If you take fiber supplements, be sure to drink plenty of water or other fluids every day. Otherwise fiber supplements can actually make your constipation worse. Also, add fiber to your diet slowly to avoid problems with gas.

If you have intestinal problems, consult your doctor before adding a fiber supplement to your diet. Also, ask your doctor or a pharmacist whether a fiber supplement may interact with any medications you take. Fiber supplements can decrease the absorption of certain medications, such as aspirin, warfarin and carbamazepine. Fiber supplements can also reduce blood sugar levels, which may require an adjustment in your insulin dosage if you have diabetes.

HOW TO PREPARE FOODS TO RETAIN DIETARY FIBER

Dietary fiber can be reduced in foods during preparation and cooking. To retain dietary fiber:

• Serve fruits and vegetables with edible skins and seeds.
• Use whole-grain flours.

Whole grains are cereal grains that consist of the intact, ground, cracked, or flaked kernel, which includes the bran, the germ, and the inner most part of the kernel (the endosperm).

Some examples of whole grains include whole wheat, oatmeal, whole-grain cornmeal, brown rice, whole-grain barley, whole rye, and buckwheat. Spelt, often thought of as a unique whole grain, is actually a member of the wheat family.

When trying to select products that contain whole grains, look for those that show whole grains listed first on the ingredient list. The ingredient list on a food label shows ingredients in the order of the most abundant by weight.

For products such as bread or pasta to be labeled whole grain, the grain can be ground, cracked, or flaked, but it must retain the same proportions of bran, germ, and endosperm.

WHAT IS A SERVING?

The serving sizes used on the list of sources of dietary fiber are only estimates of the amounts of food you might eat. The amount of nutrient in a serving depends on the weight of the serving. For example, 1/2-cup of a cooked vegetable contains more fiber than 1/2 cup of the same vegetable served raw, because a serving of cooked vegetable weighs more. Therefore, the cooked vegetable may appear on the list while the raw form does not. The raw vegetable provides dietary fiber - but just not enough in a 1/2-cup serving to be a significant source of dietary fiber.

Eating at least three or more one-ounce equivalents of whole grains daily can reduce the risk of some diseases, according to the 2005 Dietary Guidelines for Americans.

WHAT ARE SOURCES OF DIETARY FIBER?


     FOOD                                    SELECTED
                                             SERVING SIZE(1)


BREADS, CEREALS, AND OTHER GRAIN PRODUCTS


Bagel, whole-wheat	1 medium

Biscuit, whole-wheat	1 medium

Breads, multigrain, pumpernickel, rye,

  white, and whole-wheat blend, whole-wheat,

  or whole-wheat with raisins	2 regular slices

Bulgur, cooked or canned	2/3 cup

English muffin, whole-wheat	1

Muffins, bran or whole-wheat	1 medium

Oatmeal:

  Instant, fortified, prepared	2/3 cup

  Regular or quick, cooked	2/3 cup

Pita bread, whole-wheat	1 small

Ready-to-eat bran cereals	1 ounce

Rolls:

  Multigrain	1 large

  Whole-wheat	1 medium


FRUITS


Apples:

  Dried, cooked, unsweetened	1/2 cup

  Raw	1 medium

Applesauce, unsweetened	1/2 cup

Apricots, dried:

  Cooked, unsweetened	1/2 cup

  Uncooked	1/4 cup

Banana, raw	1 medium

Blackberries, raw or frozen, unsweetened	1/2 cup

Blueberries, frozen, unsweetened	1/2 cup

Dates, chopped	1/4 cup

Fruit mixture, dried	1/4 cup

Guava, raw	1

Kiwifruit, raw	1 medium

Mango, raw	1/2 medium

Nectarine, raw	1 medium

Orange, raw	1 medium

Peaches, dried:

  Cooked, unsweetened	1/2 cup

  Uncooked	1/4 cup

Pears:

  Canned, juice-pack	1/2 cup

  Dried, cooked, unsweetened	1/2 cup

  Dried, uncooked	1/4 cup

  Raw	1 medium

Prunes, dried:

  Cooked, unsweetened	1/2 cup

  Uncooked	1/4 cup

Raisins	1/4 cup

Raspberries, raw or frozen, unsweetened	1/2 cup

Strawberries, frozen, unsweetened	1/2 cup

Tangelo, raw	1 medium


VEGETABLES


Artichoke, globe (french), cooked	1 medium

Beans, green or lima, cooked	1/2 cup

Beets, cooked	1/2 cup

Broccoli, cooked	1/2 cup

Brussels sprouts, cooked	1/2 cup

Cabbage, cooked	1/2 cup

Carrots, cooked	1/2 cup

Okra, cooked	1/2 cup

Parsnips, cooked	1/2 cup

Peas, green, cooked	1/2 cup

Potato, boiled, with skin	1 medium

Snow peas, raw or cooked	1/2 cup

Spinach, cooked	1/2 cup

Squash, winter, cooked, mashed	1/2 cup

Sweetpotato, baked or boiled	1 medium

Tomatoes, stewed	1/2 cup


MEAT, POULTRY, FISH, AND ALTERNATES


Dry Beans, Peas, and Lentils

  Beans; black-eyed peas (cowpeas),

    calico, chickpeas (garbanzo beans),

    lima, mexican, pinto, red kidney,

    or white; cooked	1/2 cup

  Lentils, cooked	1/2 cup

  Peas, split, green or yellow, cooked	1/2 cup


Nuts and Seeds

  Almonds or chestnuts, roasted	2 tablespoons

  Peanut butter	2 tablespoons

  Pine nuts (pignolias)	2 tablespoons

  Pumpkin or squash seeds, hulled, roasted	2 tablespoons

  Sesame seeds	2 tablespoons

  Sunflower seeds, hulled, unroasted	2 tablespoons


(1) A selected serving size contains at least 2 grams of dietary fiber.