The custom of chewing the resin of the sapodilla tree was originally practiced by these people, which was imitated by people from Europe and spread to the rest of the world, where gum was first introduced.
The original ingredient of gum was chicle, which was taken from the sapodilla tree. The gum was made by adding a sweet taste and a good aroma to the chicle.
Recently, however, other ingredients have been used in place of the natural chicle. For example, they use vinyl saccharide resin, which is a member of the plastic family, to add color, flavor, and smell.
Most of the gum we chew today is flavored plastic.