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Get the Facts on Fiber 

What is fiber?

Fiber is the carbohydrate in plant foods that your body can’t digest. There are two types:

1. Soluble fiber dissolves in water.
Sources include:

  • Oat
  • Barley
  • Beans
  • Lentils
  • Various other fruits and vegetables

2. Insoluble fiber does not dissolve in water.
Sources include:

  • Dark leafy greens
  • Whole-wheat foods
  • Seeds
  • Nuts
  • Legumes (dried beans, peas, lentils)
  • Many other fruits and vegetables

Why add fiber to your diet?

Plant foods rich in dietary fiber help protect us against cancer, specifically colorectal cancer, as well as other chronic diseases.

According to AICR, non-starchy vegetables and fruits may protect against cancers of the mouth, pharynx, larynx, esophagus, colon, rectum and stomach.

Some soluble fibers also help lower blood sugar, may aid in insulin sensitivity and help lower blood cholesterol.

Fiber in the diet also:

  • slows digestion, so you feel full longer
  • increases the bulk and weight of stool, diluting harmful substances and speeding their elimination from the body
  • protects the lining of the colon
  • helps control body weight (How?)

How much fiber is enough?

About 30 grams of fiber each day is a good minimum goal. That’s at least 5 servings of vegetables and fruit plus at least three small servings of whole grains. (1 serving of whole grains is one slice of whole-wheat bread, or ½ cup of oatmeal, or ½ cup brown rice.)

If that sounds like a lot, remember you can start slowly:

  • Add some whole grains or beans most meals.
  • Snack on foods like bananas, whole grain cereals, and nuts.
  • Simply make sure at every meal that at least 2/3 of your plate is filled with plant foods, with 1/3 or less given over to animal products, and you’ll be on track.
Dietary Fiber in Common Foods
FoodFiber (g)Energy Density
(calories per 100 g food)
Potato, baked with skin, medium
4
93
Acorn squash, baked, 1/2 C.
5
56
Carrots, cooked,1/2 C.
2
35
Broccoli, cooked, 1/2 C.
3
28
Spinach, raw, 1 C.
1
23
Apple with skin, 1 medium
3
52
Blueberries, 1/2 C.
2
57
Apricots, dried, 4 halves
1
241
Banana, 1 medium
3
89
Orange, 1 medium
3
47
Strawberries, sliced, 1 C.
3
32
Lentils, cooked, 1/2 C.
8
116
Black beans, cooked, 1/2 C.
8
132
Hummus, 1⁄4 C.
4
166
Bulgur, cooked, 1⁄2 C.
4
83
Whole-wheat spaghetti, cooked, 1⁄2 C.
3
124
Enriched spaghetti, cooked, 1⁄2 C.
1
158
Barley, cooked, 1⁄2 C.
3
123
Brown rice, cooked, 1⁄2 C.
2
111
White rice, cooked, 1⁄2 C.
0
130
Whole-wheat bread, 1 slice
2
247
White bread, 1 slice
1
266
Oatmeal, cooked, 1⁄2 C.
2
55
Grits, cooked, 1⁄2 C.
0
59
Crisped rice cereal, 1 C.
0
387
Shredded wheat, 1 C.
6
340
Bran flakes, 1 C.
7
320
Corn flakes, 1 C.
1
361
Source: USDA

Go Slowly at First

Eating very large amounts of fiber (more than 60 grams a day) or suddenly increasing your intake may lead to some digestive discomfort. Add fiber-rich foods to your diet slowly, and drink plenty of water.


Download our Factsheet About Fiber.

Published on March 16, 2012

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