What Is Dietary Fiber?


Quick Answer

Dietary fiber is the plant roughage that the body cannot digest. It is not absorbed in the intestines like other components of a person's diet. Rather, it travels through your digestive system and is passed out of the body as a major component of the feces. There are two main classes of fiber: soluble fiber, which dissolves in water, and insoluble fiber, which does not dissolve in water.

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Full Answer

Dietary fiber can be found in all natural plant foods, including fruits, vegetables and whole grains. Although it is not absorbed by the body, it is an essential part of a healthy diet, with men ages 50 and younger requiring about 38 grams per day and women ages 50 and younger requiring 25 grams of fiber per day. The Institute of Medicine recommends slightly less fiber for those over the age of 51: 30 grams for men and 21 grams for women.

Dietary fiber serves several functions in the body. It increases the bulk of the stool and makes it softer so it is easier to pass. Those who eat plenty of fiber tend to be less prone to hemorrhoids and diverticulitis because they strain less during defecation. Soluble fiber, which is found in large amounts in oats and flax seeds, helps lower cholesterol levels and keep blood sugar levels in check.

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