Dietary fiber consists of the indigestible component of plant-based foods. As it passes through the digestive tract, it cleanses the system and provides a number of health benefits. Dietary fiber is divided into two types: insoluble and soluble fiber, both of which are present in most plant foods.
While insoluble fiber absorbs water, resulting in bulkier, softer stool, soluble fiber ferments in the large intestine, producing short-chain fatty acids that significantly contribute to overall health. The American Dietetic Association (ADA) has suggested that adults consume at least 20 to 35 grams of fiber each day depending on caloric intake, while the British Nutrition Foundation recommends at least 12 to 24 grams a day. Most North Americans consume less than 50% of the recommended daily amount of dietary fiber.
Some of the world's most serious health threats may be preventable through the regular consumption of appropriate levels of soluble fiber, including cardiovascular disease, high blood pressure and its associated complications, diabetes, obesity, and many gastrointestinal disorders. It may also help prevent cancer, particularly colon cancer.
The short-chain fatty acids produced through the fermentation of soluble fiber in the large intestine serve to stabilize blood glucose levels, lower low-density lipoproteins (LDL) or "bad" cholesterol in the blood, increase the production of immune cells, and promote colon health. This fiber prevents the formation of intestinal polyps or inflammation by maintaining a healthy pH in the intestine, aids in the absorption of certain minerals, and increases the production of helpful bacteria in the colon.
Soluble fiber is present in all plant foods to some degree. Especially good sources of the nutrient include beans and other legumes, whole grains, and certain fruits and vegetables. Root vegetables such as potatoes and carrots are an excellent source, and the skins contain insoluble fiber. Broccoli, bananas, apples, and berries are also good sources of soluble fiber. Some good grain choices are barley, oats, and rye. If you find it difficult to get the recommended daily amount of soluble fiber through your diet, there is a wide variety of fiber supplements on the market, many of which should be available at your local grocery or drug store.