referring to dietary fiber, the the parts of fruits, vegetables, and other plants that are not digested by humans. Fibers are grouped as soluble (like oat bran) and insoluble (like wheat bran). Beans, vegetables, whole grains, and fruits are good sources of fiber. Links between fiber intake alone and lower risk of cancer are not proven, but eating these foods is still recommended because they contain other substances that may help prevent cancer. They also have other health benefits.