Fibers have molecular bonds that are resistant to human intestinal enzymes, so they pass through the small intestine undigested, get broken down a bit by bacteria in the large intestine, and ultimately end up as bulk matter in the stool.

纤维素各分子间的化学键无法被人体的消化酶水解，所以它们经过小肠而不会被消化吸收，只是在大肠内肠道菌的作用下被少量分解，最终成为团块状，同粪便排出体外。