Dietary fiber includes many different plant carbohydrates that are not digested by humans. Fibers are either “soluble” (like oat bran) or “insoluble” (like wheat bran and cellulose). Soluble fiber helps lower the risk of heart disease by reducing blood cholesterol levels. Fiber is also linked with improved bowel function. Good sources of fiber are beans, vegetables, whole grains, and fruits.
Links between fiber and cancer risk are weak. Still, eating fiber-rich foods is recommended because they contain other nutrients that may help reduce cancer risk. They also have other health benefits, such as reduced risk of heart disease.