Insoluble fibers are not soluble in water and are sometimes termed structured fibers. The fiber holds water and speeds movement of the intestinal contents. Whole grains and wheat bran are particularly effective. May help prevent diverticular disease and risk of colon cancer. High fiber foods provide a feeling of fullness because of their bulk.
Soluble fibers form a gel in water and consist of pectins, beta-glucans and gums.
Good sources of soluble fiber are barley, oats, and some fruits and vegetables, especially legumes. Health benefits of soluble fiber are due to metabolism of nutrients through the bloodstream Lowers blood cholesterol in some people, particularly when eaten as part of a low-fat diet. This decreases risk of heart disease. Slows digestion of all carbohydrates, thus helping to control blood sugar. This may be particularly helpful for persons with diabetes or insulin resistance.