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It used to be when we thought about fiber, one word likely came to mind: “roughage.” These days, the benefits of what's essentially the nondigestible components of plant foods are seen as much bigger. Fiber's even been called “the new protein” for all the attention it's attracting.
Among other things, fiber-rich diets have been shown to reduce the risk for obesity, type 2 diabetes, cancer and, most significantly, cardiovascular disease, says Joanne Slavin, a registered dietitian and professor of food science and nutrition at the University of Minnesota.
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The growing awareness of the critical role our gut microorganisms (microbiota) play in both physical and mental health has also brought heightened interest to the benefits of consuming fiber-rich foods.
Not all fiber is the same
We're also learning more about the different types and properties of dietary fiber, which has for some time been divided into soluble and insoluble types. Soluble fiber, which dissolves in water, can help lower glucose levels and blood cholesterol. Foods with soluble fiber include oatmeal, nuts, beans, lentils, apples and blueberries.
Insoluble fiber helps food move through your digestive system, preventing constipation. Foods with this type of fiber include wheat, whole wheat bread, whole grain couscous, brown rice, legumes, carrots, cucumbers and tomatoes.
More recently recognized, however, are factors such as viscosity and fermentability. For example, the viscous and soluble fibers found in oats, barley and psyllium form a gel in the intestinal tract, which slows digestion and binds with cholesterol and fats, thereby helping to control blood sugar and lower blood lipids.