Xylitol is a naturally occurring sugar alcohol that is commonly used as a sugar substitute. It is naturally occurring in some fruits and vegetables and is produced commercially from the bark of birch trees and other plant materials such as corn cobs and sugar cane bagasse. Making xylitol involves extracting the xylan, a component of the plant material, which is then hydrolyzed and fermented to produce xylose. The xylose is then hydrogenated to create xylitol. Xylitol similar in sweetness to sugar, but has 40% fewer calories. It is sold under various brand names and used in many low-calorie or low-carbohydrate packaged foods, and is also commonly used in chewing gums.