Xylitol is a naturally occurring sugar alcohol that can be used as a sugar substitute in many foods and products. It is often used in chewing gum, candy, and toothpaste because it has a sweet taste but is not harmful to teeth like regular sugar. Synonyms for xylitol include birch sugar, wood sugar, and pentitol. Birch sugar is a popular name for xylitol because it can be extracted from birch trees. Wood sugar is another term that refers to xylitol because it can also be found in other hardwood trees. Pentitol is a chemical classification for xylitol and other sugar alcohols that have five carbon atoms.