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Dietary Fiber
9.333
Fact Sheet No. Food and Nutrition Series|Health
by J. Clifford, K. Niebaum, L. Bellows (3/15)
Can high-fiber diets really do all they Listed below in Table 1 are dietary sources Quick Facts
claim to do? Studies have looked at the of soluble and insoluble fiber:
relationship between high-fiber diets and • Fiber may be beneficial
many diseases, including colon cancer, Table 1: Sources of dietary fiber. in treating or preventing
coronary heart disease and diabetes. Soluble Fiber Insoluble Fiber constipation, hemorrhoids and
Proven benefits of a high-fiber diet include beans whole grains diverticulosis.
prevention and treatment of constipation, oat bran fruits
hemorrhoids and diverticulosis. In addition, fruits vegetables • Water-soluble fiber helps
certain types of fiber help decrease blood vegetables beans decrease blood cholesterol
cholesterol levels. levels.
Benefits of Fiber • Foods containing dietary fiber
What Is Dietary Fiber? include fruits, vegetables, nuts
Dietary fiber comes from the portion of Digestion and grains.
plants that is not digested in the intestinal Insoluble fiber binds water as it passes
tract. Part of it, however, may be broken through the digestive tract, making • Include a variety of high-fiber
down by bacteria in the lower gut. stools softer and bulkier. Therefore, fiber, foods in the diet.
Different types of plants vary in especially that found in whole grain
their amount and kind of fiber. Fiber products, is helpful in the treatment and
includes pectin, gum, mucilage, cellulose, prevention of constipation, hemorrhoids
hemicellulose and lignin. and diverticulosis. Diverticula are pouches
Soluble Fiber of the intestinal wall that can become
inflamed and painful. This inflammatory
Pectin and gum are water-soluble condition is called diverticulosis. In the
fibers found inside plant cells. They slow past, a low-fiber diet was prescribed for this
the passage of food through the intestines condition. It is now known that a high-
but do nothing to increase fecal bulk. fiber diet gives better results at preventing
Soluble fibers have been shown to decrease inflammation once the inflammation has
cholesterol and lower blood glucose. Beans, subsided.
oat bran, fruit and vegetables contain Cholesterol
water-soluble fiber. Low blood cholesterol levels (below
Insoluble Fiber 200 mg/dl.) have been associated with a
Fibers in cell walls are water insoluble. reduced risk of coronary heart disease. The
These include cellulose, hemicellulose and body uses cholesterol in the production
lignin. Such fibers increase fecal bulk and of bile acids some of which are excreted
speed up the passage of food through daily. The consumption of water-soluble © Colorado State University
the digestive tract. Wheat bran and whole fiber binds to bile acids, suggesting that a Extension. 12/98. Revised 7/15
grains contain the highest amounts of high-fiber diet may result in an increased extension.colostate.edu
insoluble fiber, but vegetables and beans excretion of cholesterol. Some types of
also are good sources. fiber, however, appear to have a greater
effect than others. The fiber found in rolled
oats is more effective in lowering blood
cholesterol levels than the fiber found
in wheat. Pectin has a similar effect in
*July, 2015, reviewed and revised by Colorado State lowering the amount of cholesterol in the
University Jessica Clifford, Research Associate and Extension blood. Pectin is found in some fruits such as
Specialist and K. Maloney, graduate student in the Dept of apples, pears, and citrus fruits.
Food Science Human Nutrition. Original publication by Kate Cancer
Tophman, CSU food science and human nutrition graduate
student. 12/2010
Table 2:Dietary fiber content of foods High-fiber diets may also reduce The removal of seeds, peels or
Serving size Fiber(grams) the risk of developing some types of hulls also reduces fiber content. Whole
Breads, cereals,grains cancer, especially colon cancer. This idea tomatoes have more fiber than peeled
White bread 1 slice 0.6 is based on information that insoluble tomatoes, which have more than tomato
Whole grain bread 1 slice 1.7 fiber increases the rate at which wastes juice. Likewise, whole wheat bread
100% All Bran 1/2 cup 8.8 are removed from the body. This means contains more fiber than white bread.
Corn Flakes 1 cup 0.7 the body may have less exposure to toxic Table 2 lists the dietary fiber content of
Shredded Wheat 2 biscuits 5.5 substances produced during digestion. some common foods.
Oatmeal, cooked 1 cup 4.0 While many studies have shown an Functional Fiber
Rice, brown, cooked 1/2 cup 1.75 association between increased fiber Functional fiber is a newer term that
Rice, white, cooked 1/2 cup 0.3 intake and reduced prevalence of colon includes foods that consist of isolated,
Fruit (fresh unless 26
otherwise noted) cancer, the mechanisms of how fiber nondigestible carbohydrates that
Apple, with skin 1 large 3.3 consumption may reduce cancer risk are have beneficial physiological effects
Apricots 1 0.7 still unknown. in humans. Cellulose, chitin, beta
Banana 1 3.1 Weight loss glucans, gums, inulin, oligofructose,
Blackberries 1 cup 7.6 High-fiber diets may be useful for fructoligosaccharides, lignin, pectins,
Dates 5 3.3 people who wish to lose weight. Fiber psyllium, and resistant starches are forms
Grapes 10 n/a itself has no calories, yet provides a “full” of functional fiber when added to foods.
Grapefruit, pink and 1/2 2.0
red feeling because of its water-absorbing Inulin or chicory inulin is one functional
Grapefruit, white 1/2 1.3 ability. For example, an apple that fiber that is receiving more attention, as it
Melon, cantaloupe 1 cup 1.4 contains fiber is more filling than a half is being added into many food products.
Nectarine 1 2.3 cup of apple juice that contains about the While 10 grams per day of chicory inulin
Orange 1 small 3.1 same calories but no fiber. Foods high in has been shown to be well-tolerated
Peach 1 1.5 fiber often require more chewing, thus in healthy adults, higher intakes have
Pear 1 medium 5.1 it takes more time to eat, so a person is been associated with gas and bloating.
Pineapple 1 cup 2.2 unable to eat a large number of calories in Therefore, it is recommended to consume
Plums 1 small 0.9 a short amount of time. functional fiber in moderation as a part of
Prunes, dried 5 3.0 Diabetes and Obesity a balanced diet.
Raisins 1/4 cup 1.4 Additionally, recent research suggests
Strawberries 1 cup 3.3 that a high-fiber diet rich in whole grains
Vegetables How Much Fiber?
Beans, baked, canned, 1 cup 10.4 is associated with a reduced risk for
plain developing type 2 diabetes and obesity. The average American consumes
Beans, green, cooked 1 cup 4.0 Greater consumption of fiber found in 14 grams of dietary fiber a day, which is
Beets, canned 1 cup 2.9 whole grains, compared to refined grains, considerably less than the recommended
Broccoli, raw 1 cup 2.3 has been shown to modestly reduce level. The 2010 Dietary Guidelines for
Cabbage, raw 1 cup 1.6 glycemic index and improve insulin Americans recommends 14 grams of
Carrots, raw 1 cup 3.1 sensitivity, resulting in an decreased fiber per 1000 calories consumed. So, if
Cauliflower, raw 1 cup 2.5 you consume a 2,500 calorie diet, you
Celery, raw 1 cup 1.9 risk for developing type 2 diabetes and
Corn, yellow, cooked 1 cup 3.9 obesity. To increase your fiber intake, it should eat approximately 35 grams of
Lentils, cooked 1 cup 15.6 is recommended by the 2010 Dietary fiber per day. Also, fiber intake may vary
Lettuce, romaine, raw 1 cup 1.2 Guidelines for Americans to make at least depending on age and gender.
Lettuce, iceberg, raw 1 cup 0.7 half of grains consumed whole grains for While the 2010 Dietary Guidelines
Peas, boiled 1 cup 4.5 optimal health. for Americans serves as a general
Peas, split 1 cup 16.3 guide to healthy eating, the Dietary
Potato, baked, fresh 1/2 potato 2.3 Reference Intakes (DRIs) provide standard
Sweet potato, cooked 1/2 potato 3.9 Sources of Fiber recommended amounts for nutrients.
without skin Foods
Tomato, red, ripe 1 tomato 1.5 Dietary fiber is found only in plant In 2002, the Food and Nutrition Board
Winter squash, cooked 1 cup 5.7 of the National Academy of Sciences
Zucchini squash 1/2 cup n/a foods: fruits, vegetables, nuts and grains. Research Council issued DRIs for fiber
Other foods Meat, milk and eggs do not contain fiber. (see Table 3). Previously, no national
Meat, milk, eggs 0 The form of food may or may not affect standardized recommendation existed.
Almonds (24 nuts) 1 oz. 3.3 its fiber content. Canned and frozen fruits The new DRIs represent desirable intake
Peanuts, dry roasted 1 oz. 2.3 and vegetables contain just as much fiber levels established using the most recent
(approx. 28) as raw ones. Other types of processing,
Walnuts, English (14 1 oz. 1.9 though, may reduce fiber content. Drying scientific evidence available.
halves) Although fiber is important, it is
and crushing, for example, can destroy just one part of a balanced diet, and
the water-holding qualities of fiber. For like all foods, should be consumed in
this reason, dried fruit may have less fiber moderation It is possible that too much
than raw fruit. fiber may reduce the amount of calcium,
iron, zinc, copper and magnesium that Table 3: Dietary Reference Intakes in fruits, vegetables and grain products
is absorbed from foods. Deficiencies of (DRI) for Fiber. that contain fiber, particularly soluble
these nutrients could result if the amount Age g/day Fiber fiber, may reduce the risk of coronary
of fiber in the diet is excessive, especially heart disease.” In order to make a health
in young children. Children claim about fiber and coronary heart
Tips for increasing fiber 1-3 years 19 disease, the food must contain at least 0.6
For many people, meeting the DRI for 4-8 years 25 g of soluble fiber per reference amount.
fiber may require changes in their eating Males The soluble fiber content must be listed
habits. Consider the following tips when 9-13 years 31 and cannot be added or fortified. A
increasing fiber in your diet: 14-18 years 38 product containing a health claim for
• Aim for at least 3servings of whole fiber and coronary heart disease must
grains a day, such as oatmeal for 19-50 years 38 also meet the definitions of a low fat, low
breakfast, whole wheat bread at 51+ years 30 in saturated fat and low in cholesterol
lunch, and brown rice with dinner. Females product.
• Try adding more legumes to your 9-13 years 26 A statement such as “made with
diet. Add black beans to a burrito or 14-18 years 26 oat bran” or “high in oat bran” implies
chick peas to a salad. that a product contains a considerable
• Increase your daily fruit and 19-50 years 25 amount of the nutrient. Claims that imply
vegetable intake. Aim for 5 servings 51+ years 21 a product contains a particular amount
total per day. Choose whole fruits Pregnancy 10 of fiber can be made only if the food
more often than dried fruit or fruit <18 years 28 actually meets the definition for “high
juices. Cut up veggies for an easy fiber” or “good source of fiber,” whichever
snack throughout the day. Make 18+ years 28 is appropriate.
gradual increases. If you are not used Lactation The following terms describe products
to eating high fiber foods regularly, <18 years 29 that can help increase fiber intake:
changes should be made gradually 18+ years 29 • High fiber: 5 g or more per serving
to avoid problems with gas and • Good source of fiber: 2.5 g to 4.9 g
diarrhea. Drink plenty of water to Figure1: Nutrition Facts Label Showing Fiber per serving
minimize intestinal gas. If problems Listed in Grams • More or added fiber: At least 2.5 g
with gas continue to be an issue, more per serving than the reference
gas-reducing over-the-counter and food
prescription drugs are available. Supplements
• Anyone with a chronic disease should Fiber supplements are sold in a
consult a physician before greatly variety of forms from bran tablets to
altering a diet. purified cellulose to powdered psyllium.
Many laxatives sold as stool softeners
Food Labeling of Fiber are actually fiber supplements. Fiber’s
Nutrition Facts Label role in the diet is still being investigated.
Nutrients required on the Nutrition It appears that the various types of
Facts Label reflect current public health fiber have different roles in the body.
recommendations. The Nutrition Facts Furthermore, fiber may interact with
Label list a Daily Reference Value (DRV) for prescription medications. If you are taking
specific nutrients, including fiber. The DRV prescription medications, check with your
for fiber is 25 grams per day based on a doctor before taking a fiber supplement.
2,000 calorie diet, or 30 grams per day
based on a 2,500 calorie diet. The fiber Summary
content of a food is listed in grams and as It is recommended to meet dietary
a percentage of the daily value. fiber recommendations by eating a
Figure 1 shows a food nutrition label. It variety of fiber-rich foods. This is the best
tells you the product provides 3g of fiber way to receive the maximum benefits
in a half cup serving. The percent Daily from each type of fiber present in foods,
Value for one serving is 12 percent, or 12 and obtain necessary nutrients.
percent of DRV of 25 grams based on a
2,000 calorie diet.
Health Claims
Specific health claims can be made
for food products that meet specific
requirements. For example: “Diets low
in saturated fat and cholesterol and rich
References
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• Bonnema, A., Kolberg, L., Thomas, W.,
& Slavin, J. (2010). Gastrointestinal
Tolerance of Chicory Inulin Products.
Journal of the American Dietetic
Association, 110(6), 865-868.
• Cho, S., Qi L., Fahey, G., & Klurfeld,
D. (2013). Consumption of cereal
fiber, mixtures of whole grains
and bran, and whole grains and
risk reduction type 2 diabetes,
obesity, and cardiovascular disease.
The American Journal of Clinical
Nutrition, 594-619.
• Food Labeling Guide. (2013).
Washington, DC: U.S. Food and Drug
Administration, Center for Food
Safety and Applied Nutrition.
• Institute of Medicine. (2005). Dietary
Reference Intakes for Energy,
Carbohydrate, Fiber, Fat, Fatty Acids,
Cholesterol, Protein, and Amino
Acids (Macronutrients). National
Academy Press p. 265-334.
• Kaczmarczyk, M., Miller, M., &
Freund, G. (2012). The health
benefits of dietary fiber: Beyond the
usual suspects of type 2 diabetes
mellitus, cardiovascular disease and
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• Lattimer, J., & Haub, M. (2010).
Effects of Dietary Fiber and Its
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Colorado State University, U.S. Department of Agriculture
and Colorado counties cooperating. CSU Extension
programs are available to all without discrimination. No
endorsement of products mentioned is intended nor is
criticism implied of products not mentioned.
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