High Fiber Diet

INTRODUCTION — Eating a diet that is high in fiber has many potential health benefits, including a decreased risk of heart disease, stroke, and type 2 diabetes.  A high fiber diet is a commonly recommended treatment for digestive problems, such as constipation, diarrhea, and hemorrhoids.  Fiber is normally found in beans, grains, vegetables, and fruits. However, most people do not eat as much fiber as is commonly recommended. This topic discusses what fiber is, why it is helpful, and how to increase dietary fiber.

 

WHAT IS FIBER? — There is no single dietary "fiber". Traditionally, fiber was considered that substance found in the outer layers of grains or plants and which was not digested in the intestines. Wheat bran, the outer layer of wheat grain, fit this model. We now know that "fiber" actually consists of a number of different substances. The term "dietary fiber" includes all of these substances and is now considered a better term than just "fiber".

Most dietary fiber is not digested or absorbed, so it stays within the intestine where it modulates digestion of other foods and affects the consistency of stool. There are two types of fiber, each of which is thought to have its own benefits:

  • Soluble fiber consists of a group of substances that is made of carbohydrates and dissolves in water. Examples of foods that contain soluble fiber include fruits, oats, barley, and legumes (peas and beans).
  • Insoluble fiber comes from plant cells walls and does not dissolve in water. Examples of foods that contain insoluble fiber include wheat, rye, and other grains. The traditional fiber - wheat bran - is a type of insoluble fiber.
  • Dietary fiber is the sum of all soluble and insoluble fiber.

HOW MUCH FIBER DO I NEED? — The recommended amount of dietary fiber is 25 grams (for women) to 30 grams (for men) of fiber per day. By reading the nutrition label on packaged foods, it is possible to determine the number of grams of dietary fiber per serving.

Dietary sources of fiber — The fiber content of many foods, including fruits and vegetables, is shown in the table.  Breakfast cereals can be a good source of fiber. Some fruits and vegetables are particularly helpful in treating constipation, such as prunes and prune juice.

Other sources of fiber — For those who do not like high-fiber foods such as fruits, beans, and vegetables, a good source of fiber is unprocessed wheat bran; one to two tablespoons can be mixed with food (one tablespoon contains 12 grams of fiber).

In addition, a number of fiber supplements are available.  Fiber-Sure and Benefiber are easily available and well-tolerated. The dose of the fiber supplement should be increased slowly to prevent gas and cramping, and the supplement should be taken with adequate fluid. The fiber in these supplements is mostly of the soluble type.


SIDE EFFECTS — Adding fiber to the diet can have some side effects, such as abdominal bloating or gas. This can sometimes be minimized by starting with a small amount and slowly increasing until stools become softer and more frequent.  However, many people, including those with irritable bowel syndrome, cannot tolerate fiber supplements and do better by not increasing fiber in their diet.


 

Dietary Fiber of certain foods

Food

Fiber, g/serving

Cucumber

0.2/6-8 slices with skin

Lettuce

2.0/1 wedge iceberg

Mushrooms

0.8/half cup (sliced)

Onions

1.3/1 cup

Peppers, green

1.0/1 pod

Tomato

1.8/1 tomato

Spinach

8.0/1 cup (chopped)

Baked beans

18.6/1 cup

Dried peas

4.7/half cup (cooked)

Kidney beans

7.4/half cup (cooked)

Lima beans

2.6/half cup (cooked)

Lentils

1.9/half cup (cooked)

Bagels

1.1/half bagel

Bran muffins

6.3/muffin

Cracked wheat

4.1/slice

Oatmeal

5.3/1 cup

Pumpernickel bread

1.0/slice

White bread

0.55/slice

Whole-wheat bread

1.66/slice


 

 

Apple (with skin)

3.5/1 medium-sized apple

Apricot (fresh)

1.8/3 apricots

Banana

2.5/1 banana

Cantaloupe

2.7/half edible portion

Dates

13.5/1 cup (chopped)

Grapefruit

1.6/half edible portion

Grapes

2.6/10 grapes

Oranges

2.6/1 orange

Peach (with skin)

2.1/1 peach

Pear (with skin)

4.6/1 pear

Pineapple

2.2/1 cup (diced)

Prunes

11.9/11 dried prunes

Raisins

2.2/packet

Strawberries

3.0/1 cup

Apple

0.74/1 cup

Grapefruit

1.0/1 cup

Grape

1.3/1 cup

Orange

1.0/1 cup

Cooked vegetables

 

Asparagus

1.5/7 spears

Beans, string, green

3.4/1 cup

Broccoli

5.0/1 stalk

Brussels sprouts

4.6/7-8 sprouts

Cabbage

2.9/1 cup (cooked)

Carrots

4.6/1 cup

Cauliflower

2.1/1 cup

Peas

7.2/1 cup (cooked)

Potato (with skin)

2.3/1 boiled

Spinach

4.1/1 cup (raw)

Squash, summer

3.4/1 cup (cooked, diced)

Sweet potatoes

2.7/1 baked

Zucchini

4.2/1 cup (cooked, diced


    Still more foods and their fiber contents

    Food

    Fiber, g/serving

    Macaroni

    1.0/1 cup (cooked)

    Rice, brown

    2.4/1 cup (cooked)

    Rice, polished

    0.6/1 cup (cooked)

    Spaghetti (regular)

    1.0/1 cup (cooked)

    Bran, oat

    8.3/oz

    Bran, wheat

    12.4/oz

    Rolled oats

    13.7/1 cup (cooked)

    Nuts

     

    Almonds

    3.6/half cup (slivered)

    Peanuts

    11.7/1 cup