The indigestible portion of fruits, vegetables, and grains. There are two main types of dietary fiber: soluble fiber and insoluble fiber. Both are believed to be important for maintaining good health.
Soluble fiber is found in oats and oat bran, beans, some fruits and vegetables, and psyllium (used in some over-the-counter fiber laxatives and breakfast cereals). Diabetes researchers believe that consuming large amounts of soluble fiber (over 50 grams a day) may help control blood glucose levels after meals by slowing the rate of carbohydrate absorption in the intestine. Soluble fiber has also been shown to lower blood cholesterol and triglyceride levels by binding to cholesterol and helping to pass it out of the body.
Insoluble fiber is found primarily in the cell walls of plants. Good dietary sources include whole grains and unpeeled fruits and vegetables. Insoluble fiber helps prevent constipation and may help prevent weight gain by increasing bulk in the diet, making you feel fuller.
Nutrition experts recommend that adults consume 20 to 35 grams of fiber daily. For children, the recommended amount is the child’s age plus five, so, for example, a five-year-old needs about 10 grams of fiber a day. Drinking plenty of water and other fluids—at least 8 cups a day—is necessary for fiber to do its job.