Dietary fiber found in fruits, vegetables and grains provides benefits for health, digestion and prevention of disease. According to the University of Maryland Medical Center, dietary fiber does not get digested in the body. The stomach and intestine metabolize only a small amount of fiber and the rest passes through the digestive tract as part of the stool. Although not digested, fiber does provide important functions in a healthy diet and assists with weight management.
Identification
The two types of dietary fiber are soluble and insoluble. Insoluble fiber moves quickly through the stomach and intestine. According to the University of Maryland Medical Center soluble fiber attracts water and becomes a gel during digestion. This slows down digestion and absorption of nutrients from the stomach and intestine. As an example of soluble fiber, pectin from fruit is used to thicken jellies. Insoluble fibers do not dissolve in water and include tough fibrous structures such as the skins of corn kernels and the strings of celery.
Function
Dietary fiber adds bulk to the diet. Fiber helps digestion and lessens constipation. Because it makes a person feel full faster, it helps control weight. And dietary fiber appears to exert a preventive effect against cancer risk, according to Kathleen Mahan and Sylvia Escott-Stump in the text "Krause's Food, Nutrition and Diet Therapy."
Often recommended to treat diverticulosis, or pouches that develop in the weakened intestinal wall and to treat diabetes, soluble fiber also lowers low-density lipoprotein, also called LDL, the so-called "bad"cholesterol, and helps prevent and treat heart disease, according to the National Library of Medicine. Insoluble fiber binds with bile acids and reduces the amount of fat and cholesterol absorbed by the body.
Food Sources
Food sources of soluble fiber include oat bran, barley, seeds, nuts and lentils, as well as some fruits and vegetables. Legumes including dried peas and beans provide an excellent source of soluble fiber. Foods that contain insoluble fiber include wheat bran, vegetables and whole grains.
Recommendations
Dietary recommendations for adults, according to Eleanor Whitney and Sharon Rolfes in the text "Understanding Nutrition," include 20 to 35 grams of fiber per day. To increase fiber intake, choose whole grain cereals, eat raw vegetables and fruits with their skins, add legumes to soups and salads and select fruit for snacks.
Possible Side Effects
Eating too much fiber can interfere with the body's absorption of iron, zinc, calcium and magnesium. Consuming too much fiber in a short time can cause flatulence, bloating and abdominal cramps from intestinal gas. Adding fiber gradually, though, can reduce gas or diarrhea as the natural bacteria in the digestive system become accustomed to the increase in fiber.
References
- University of Maryland Medical Center: Soluble and Insoluble Fiber
- "Krause's Food, Nutrition, & Diet Therapy, 10th Edition". Mahan and Escott-Stump. (2000).
- Medline Plus: Fiber
- "Understanding Nutrition, Ninth Edition", Eleanor Noss Whitney and Sharon Rady Rolfes (2002).
- Medline Plus: Soluble versus Insoluble Fiber
Member Comments