Only food plants provide fiber the carbohydrate components of leaves, roots, and seeds that cannot be digested by salivary or intestinal enzymes. Fiber adds bulk, absorbs water, and aids elimination from the intestine. Food fiber is classified as soluble or insoluble. Soluble fiber includes pectins and other indigestible starches from fruits, oats, and beans; it helps reduce levels of blood cholesterol and control fluctuations in blood glucose levels. Insoluble fiber comes from the outside layers of wheat and other grains and promotes the health of the digestive tract. Eating more fiber simply means eating more fruits, vegetables, and whole grains.
