Is Insoluble Fiber Good Or Bad?

Plant-based foods contain fiber that your body does not digest and absorb as a nutrient but needs for its other important contributions to your health. Soluble fiber may improve your blood glucose levels and lower your cholesterol. Insoluble fiber adds bulk to your stool and helps prevent constipation. Most fiber passes intact through your digestive system to the large intestine, where bacteria residing in your colon help digest part of the fiber to produce fatty acids and gas. Fibers help regulate the passage of food through your digestive system, but they provide little or no energy.

Definition

Insoluble fibers are the indigestible components of food that do not dissolve in water. The tough, fibrous strings of celery and the skins of corn kernels provide examples of insoluble fiber. Their inability to dissolve in water distinguishes insoluble fibers from soluble fibers such as the pectin in fruit that dissolves to form the gel that thickens jelly.

Food Sources

Food sources for insoluble fiber include wheat bran, corn bran, whole-grain breads, whole-grain cereals and vegetables such as carrots, Brussels sprouts and cabbage. Choose whole-grain products, vegetables, fruits, beans and peas, and nuts and seeds to meet your body's needs for fiber.

Benefits

Insoluble fibers speed up the transit of food through your digestive tract. They promote healthy bowel movements and slow down the chemical breakdown of starchy foods. Insoluble fibers also delay the absorption of glucose, according to "Understanding Nutrition."

Recommended Daily Intake

The American Dietetic Association recommends 25 g of fiber per day for women and 38 g fiber per day for men, which is roughly twice the average intake in the United States, according to "Understanding Nutrition." MayoClinic.com recommends 22 to 28 g of fiber per day for women and 28 to 34 g of fiber per day for men. Of your total recommended fiber intake, 6 to 10 g should come from soluble fiber and the rest from insoluble fiber, according to "Krause's Food, Nutrition, & Diet Therapy." Eat five or more servings of fruits and vegetables and six or more servings of whole grains and high-fiber cereals each day.

Excessive Intake

A high-fiber diet in excess has a few drawbacks. It may displace energy-dense foods or nutrient-dense foods. The malnourished, elderly and children on a vegan diet may have little overall food intake and high-fiber foods may fill them up before they consume enough nutrients. Too much fiber may cause intestinal discomfort and distention or bloating, especially if you change suddenly to a high-fiber diet without allowing your body to adapt slowly. Insoluble fibers may decrease your absorption of some nutrients because of their rapid transit through your gastrointestinal tract. Some minerals may bind to the fiber and get excreted rather than absorbed. When your mineral intake is sufficient and your fiber intake is less than 40 g per day, however, insoluble fiber provides a valuable part of a balanced, healthy diet, according to "Understanding Nutrition."