Xylitol, also called wood sugar or birch sugar, is a five-carbon sugar alcohol that is used as a sugar substitute. Xylitol is a naturally occurring sweetener found in the fibers of many fruits and vegetables, including various berries, corn husks, oats, and mushrooms. It can be extracted from corn fiber, birch, raspberries, plums, and corn. Xylitol is roughly as sweet as sucrose but contains 40% less food energy.