|Many studies have found that diets low in saturated fat and cholesterol and high in fiber are associated with a reduced risk of certain cancers, diabetes, digestive disorders, and heart disease. High-fiber foods may also contain antioxidant vitamins, phytochemicals, and other substances that may offer protection against diseases.
Recent findings show fiber may play a role in:
Cancer: A 1992 study by Harvard Medical School found that men who consumed 12 grams of fiber a day were twice as likely to develop precancerous colon changes as men whose daily fiber intake was about 30 grams. Scientists speculate that insoluble fiber adds bulk to stool, which dilutes carcinogens and speeds then through the lower intestines and out of the body.
In early stages, some breast tumors are stimulated by excess amounts of estrogen circulating in the bloodstream. Some believe that fiber hampers the growth of tumors by binding estrogen in the intestine. This stops excessive estrogen from being absorbed into the bloodstream.
Digestive problems: Insoluble fiber aids digestion and adds bulk to stool. Fiber hastens the passage of fecal matter, helping prevent or ease constipation. Fiber also may help reduce the risk of diverticulosis, a condition in which small pouches form in the colon wall (usually from the pressure of straining during bowel movements). People who already have diverticulosis often find increased fiber consumption eases symptoms.
Diabetes: Soluble fiber traps carbohydrates and slows their digestion and absorption. This may prevent swings in blood sugar levels throughout the day.
Heart Disease: Clinical studies show a diet low in saturated fat and cholesterol, and high in fruits, vegetables and grain products that contain soluble fiber can lower blood cholesterol.
Soluble fiber binds to dietary cholesterol as it passes through the gastrointestinal tract and helps eliminate it. This reduces cholesterol deposits on arterial walls that eventually choke off vessels. Soluble fiber can slow the liver's manufacture of cholesterol, as well as alter low-density lipoprotein (LDL) particles to make them larger and less dense.
Obesity: Insoluble fiber is indigestible and passes through the body virtually intact. Fiber has few calories. Since the digestive tract can process only so much bulk at a time, fiber-rich foods are more filling than other foods. People tend to eat less. Insoluble fiber also may hamper the absorption of dietary fat.