Dietary Fiber Facts

What is Dietary Fiber?

Fiber comes from plant-based foods. Fibers are the stems, seeds, skins, and supporting structure of the leaves. It is the part of the plant that the body cannot digest. There are two kinds of fiber: fibers that dissolve in water and forms gels and fibers that do not dissolve in water and pass through the body unchanged. Plant foods usually contain a mixture of both soluble and insoluble fibers. Water soluble fibers can lower blood cholesterol, slow digestion to stabilize blood sugar, and soften the stools by holding onto moisture. Insoluble fibers move solid wastes out of the body quickly to prevent constipation and some gastrointestinal diseases. Fiber can also delay hunger by creating a feeling of fullness. Fiber may prevent weight gain by providing calories that are not absorbed and displacing high-calorie refined foods.

Dietary Fiber requirements

The RDAs for fiber for healthy adults are 38gm/day for males 19-50 years old and 25 gm/day for females 19-50 years old. The RDA for fiber decreases with age. Males age 51 years and older need 30 gm/day; females age 51 years and older need 21 mg/day. The requirement for fiber varies somewhat among individuals. The average American eats about 15 grams of fiber a day - too little to meet the RDA.

What happens when Dietary Fiber intake is too high?

There are no Tolerable Upper Intake Levels for fiber. Because fiber is bulky, excess eating is thought to be self-limiting. At very high intakes, fiber can combine with certain vitamins and minerals to make them unavailable to the body in a chemical process called "chelation". However, if you eat a balanced diet, the chelating effect is not great enough to cause nutrient deficiencies. Even vegetarians, whose diets are very high in fiber, have normal vitamin and mineral levels. Fibers do carry water out of the body, which could be dehydrating. It is important to drink extra fluids to help fiber work.

What happens when Dietary Fiber intake is too low?

The short-term effect of a low fiber diet is usually constipation. A high fiber diet prevents constipation and hemorrhoids. It stimulates the muscles of the digestive track to retain their tone. Over the long-term, a low fiber diet may increase the risk of heart disease, stroke, diabetes, and gastrointestinal conditions. When increasing fiber intake, it is best to do it gradually over several weeks to prevent stomach aches, bloating, gas, and diarrhea.

Which foods are high in Dietary Fiber?

High fiber foods are unrefined grains, like whole wheat, bran, corn, oats, and brown rice, dried beans (black beans, black-eyed peas, chickpeas, etc.), lentils, split peas and whole dried peas, and fibrous fruits and vegetables, like berries, dried fruits, apples, broccoli, green, and potatoes with skins. "Purified fiber" may also be taken as a supplement. Oat bran, wheat bran, psyllium husk powder, and pectin are examples of purified fibers. There should be no need for purified fibers if the diet contains a wide variety of high fiber foods.

List of foods high in Dietary Fiber





Mixed Dishes



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