Dietary Fiber

Medically reviewed by: Gary H. Hoffman, MD

What is dietary fiber and why is it important?

Fiber is an edible material that is derived from the cell wall of plants. It is an essential part of a well-balanced diet whose importance is being increasingly recognized. Studies show that dietary fiber may help prevent such diseases as colon cancer, diverticular disease, elevated cholesterol, chronic constipation and hemorrhoids. We know, for instance, that different countries with higher fiber intakes have lower rates of colon cancer and diverticular disease. A word of caution: these studies are not conclusive or final. They are open to interpretation and need verification.

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Fiber helps food pass through the intestinal tract by drawing water into the intestine, thereby increasing the size of the bowel movement. This, in turn, decreases the amount of spasm experienced by the muscles of the intestinal tract. As a result, the colon works more efficiently and painlessly. By itself, fiber does not contribute any vitamins or nutrients and remains undigested. However, since it helps move intestinal contents along, fiber may reduce the amount of contact between the lining of the intestine and any cancer-causing agents. This mechanism of action has not been proven however.

How much dietary fiber should I eat?

It is recommended that everyone eat at least 25-30 grams of fiber daily. This can be achieved with a healthy, well-balanced diet. Different foods contain varying amounts of fiber. On this sheet is a list of foods and their fiber content. Use it as a guide if you wish to improve your intake of dietary fiber.

Another way to ingest an adequate amount of fiber is to use a fiber supplement. Examples include Metamucil, Citrucel, Konsyl (powders mixed with water), or Fibercon tablets. These products should be used on a regular basis and not erratically for optimal function. One tablespoon of Citrucel or Metamucil equals six grams of fiber.

Excellent Sources of Fiber

(At least 7 grams of fiber per serving)

Fiber Content Serving Size

  • Fiber One Cereal 13 grams ½ cup
  • All Bran Cereal 10 grams 1/3 cup
  • Prunes 10 grams ½ cup
  • Baked Kidney beans 7-9 grams ½ cup

Good Sources of Fiber

(Between 2 and 6 grams of fiber per serving)

  • Corn (on the cob) 6 grams 1
  • Spinach (cooked) 4 grams 1 cup
  • Apples/Pears/Bananas 3 grams 1
  • Baked Potato with skin 3 grams 1
  • Nuts 3 grams 1/3 cup
  • Cantaloupe/Oranges 2 grams 1/4
  • Carrots 2 grams 1
  • Peanut Butter 2 grams 2 tbsp.
  • Tomatoes 2 grams 1
  • Whole wheat bread 2 grams 1 slice
  • Oatmeal 2 grams ¾ cup
  • Raspberries 2 grams 1/3 cup
  • Strawberries 2 grams ½ cup

Poor sources of Fiber

(Less than 2 grams of fiber per serving)

  • Cauliflower 1 gram ½ cup
  • Cucumber 1 gram 1 cup
  • Grapefruit/Peaches 1 gram 1
  • Lettuce/Celery 1 gram 1 cup
  • White Bread 1 gram 1 slice
  • White rice 1 gram ½ cup
  • Grapes 0.5 gram 20
  • Popcorn 0.5 gram 1 cup

No Fiber

Beef, Chicken, Fish and most Dairy products and Beverages do not contain significant amounts of dietary fiber.

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