What exactly is Xylitol?

"Xylitol (/ˈzaɪlɪtɒl/; Greek: ξύλον, xyl[on], "wood" + suffix -itol, used to denote sugar alcohols) is a chemical categorized as a polyalcohol or sugar alcohol (alditol). Xylitol has the formula (CHOH)3(CH2OH)2 and is an achiral[2] isomer of pentane-1,2,3,4,5-pentol. Xylitol is used as a diabetic sweetener which is roughly as sweet as sucrose with 33% fewer calories. Unlike other natural or synthetic sweeteners, xylitol is actively beneficial for dental health by reducing caries to a third in regular use and helpful to remineralization. Multiple studies utilizing electron microscopy have indicated that xylitol is effective in inducing remineralization of deeper layers of demineralized enamel. Fair evidence was found that xylitol (as chewing gum, lozenges, nasal spray, etc.) reduced the incidence of acute middle ear infection in healthy children.

Xylitol is naturally found in low concentrations in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse,and birch. However, industrial production starts from xylan (a hemicellulose) extracted from hardwoods or corncobs, which is hydrolyzed into xylose and catalytically hydrogenated into xylitol. A study in rats found that xylitol had reduced or nonexistent side effects compared to other artificial sweeteners, and lower caloric value and cariogenicity than sucrose"
See more @ Wikipedia

"Xylitol: Does This Sound Natural?

My initial Google search for “xylitol” and “safe” took me straight to this Natural News article that states:

    Xylitol is a processed sugar. After being hydrogenated and having toxic chemicals added to xylan from corn or other plant material, and then removed, you get xylitol.I love Natural News with all my heart, but sometimes they can be a little bit over the top. A little bit sensational. Kind of a drama queen.Given the huge rash of xylitol ads I’ve seen recently, along with what I can only assume is a push by the Xylitol Overlords to “health bloggers” to promote their “all-natural, insulin-regulating, super-sweetener” by way of 5000 blog posts in a month, I had to look into it more.

Maybe, just this once, Natural News was wrong."
See more about the possible dangers of Xylitol @ Crunch Betty

More info...

1. About Xylitol @ WebMD
2. About possible dangers @ Crunch Betty