The average American consumes only 14 grams of fiber each day, despite extensive research that shows that higher levels off fiber provide increased health benefits. The purpose of a high-fiber diet is to encourage people to eat more fiber in order to receive the advantages of those health benefits. The high-fiber diet is not designed specifically to be a weight loss diet, although weight loss may occur as a side effect of the diet.
Dietary fiber is the collective name for a group of indigestible carbohydrate-based compounds found in plants. They are the materials that give the plant rigidity and structure. Two types of fiber are important to human health, insoluble fiber and soluble fiber.
Insoluble dietary fiber from the plants moves through the digestive system essentially unchanged. It is not digested, and it does not provide energy (calories). Instead, fiber adds bulk to the waste (stool or feces) in the large intestine (colon). Increased bulk causes the walls of the intestine to contract rhythmically (peristalsis), so that waste moves through the large intestine more rapidly. In the colon, most of the water in digested food is reabsorbed into the body, and then the solid waste is eliminated. By passing through the colon more rapidly, less water is reabsorbed from the waste. The stool remains soft and moist and is easy to expel without straining.
Good sources of insoluble fiber include:
- whole grains and foods made of whole grains, such as whole wheat bread and whole wheat pasta, couscous, or bulgur
- bran and bran breakfast cereals
- brown rice
- carrots, cucumbers, and other raw vegetables
Soluble fiber is found dissolved in water inside plant cells. Like insoluble fiber, it is not digested and does not provide energy, although it may be consumed by bacteria that live in the digestive tract. In water, soluble fiber forms a gel-like substance. This gel absorbs water and helps to keep the stool soft. Good sources of insoluble fiber include:
- oatmeal and foods made with oats
- foods such as chili or split pea soup that contain dried beans and peas
- lentils
- apples
- pears
- citrus fruits
Because fiber is so important in the diet, the amount of fiber in canned goods, frozen foods, and other processed foods sold commercially must be shown on the label. A food that is labeled “high in fiber” contains 5 or more grams of fiber per serving. As of mid-2007, manufacturers were required to show only the total amount fiber in each serving of food. However, at this time regulations were under consideration that that would require soluble dietary fiber to be listed separately from total fiber. This is because soluble fiber has health benefits that insoluble fiber does not. A good list of high-fiber foods can be found at <http://www.gicare.pated/edtgs01.htm >.
