Effect of spring oilseed rape crop density on plant root biomass and ... by Cepuliene, Rita; Marcinkeviciene, Ausra; Velicka, Rimantas; Kosteckas, Robertas; Pupaliene, Rita / Estonian Journal of Ecology.
A study in Washington State gathered 154 first to fifth graders from two elementary schools. The students were given four gummy bears made with either xylitol or maltitol (types of sugars used in many types of sugarless chewing gum) three times a day during school hours. All were checked for plaque and bacteria in their mouths at the start of the study and six weeks later.
Answer: Originally, chewing gum was made from the  latex sap of the sapodilla tree (native to Central America). This sap was called chicle. Other natural gum bases may be used, such as sorva and jelutong. Sometimes beeswax or paraffin wax is used as a gum base. After World War II, chemists learned to make synthetic rubber, which came to replace most natural rubber in chewing gum (e.g., polyethylene and polyvinyl acetate). The last U.S. manufacturer to use chicle is Glee Gum. In addition to the gum base, chewing gum contains sweeteners, flavorings, and softeners. Softeners are ingredients such as glycerin or vegetable oil that are used to blend the other ingredients and help prevent the gum from becoming hard or stiff.