Defining Fiber and Its Role
Food fibers are that part of plant foods that are not digested when eaten. Since they are not absorbed into the body, dietary fibers are not a nutrient. Nevertheless, consumers are increasingly interested in the role that dietary fibers play in maintaining the body's health.
Fiber-rich foods help with constipation, hemorrhoids, and diverticular disease. Some types of fiber may have a cholesterol-lowering effect which could lead to reduced risk of heart disease. In addition, fiber may reduce the incidence of certain types of cancer, particularly those associated with the digestive tract, and may be helpful in controlling diabetes.
Soluble and insoluble fibers make up the two basic categories of dietary fiber. Insoluble fibers ??? cellulose, hemicellulose and lignin ??? are not soluble in water. Foods which contain insoluble fibers are wheat bran, whole grain products, and vegetables. Insoluble fibers are responsible for increased stool bulk and help to regulate bowel movements.
Soluble fibers ??? gums, pectins, and mucilages ??? become gummy in water. When eaten, these fiber sources actually slow the passage of food through the digestive system. Some researchers believe this action helps to regulate cholesterol and glucose (sugar) levels in the blood by affecting absorption rates. Food sources of soluble fibers are dried beans, oats, barley and some fruits and vegetables.
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