*Xylitol, an alternative sweetener, is lower in calories and does not cause the increases or spikes in blood sugar that can happen when you eat items with cane or beet sugar. Xylitol was first discovered by French and German chemists in the late 1890s. After further research and development in Turku, Finland, Finnish company Jennki introduced a gum sweetened with xylitol (originally derived from birch trees) in 1975. Xylitol-sweetened gums, toothpastes, mouthwashes--and eventually candies, baked goods and chocolates--followed.
Note: Like chocolate, you should not feed xylitol-sweetened items to dogs. Bath can be toxic.
Dogs, cats and other animals (including ferrets, horses and bears) lack our ability to process theobromine, a naturally-occurring stimulant in cacao/chocolate; and ingestion can cause nausea, vomiting, nervous systems problems--and in rare cases, death. Whereas, most humans, rodents and certain birds are able to break down caffeine, theobromine and other plant alkaloids, more effectively. (From an evolutionary perspective, plants may have developed these bitter-tasting alkaloids, in part, as a defense mechanism to prevent animals and insects from eating them.)
Xylitol can trigger a release of insulin in dogs that cause them to become severely hypoglycemic. While xylitol can trigger milder, digestive side effects in humans, it is generally considered to be safe for us; and it may have certain desirable anti-bacterial properties (thus the inclusion in dental hygiene products). As with many new foods, try eating a small amount initially if you're unsure.