Modern chewing gum is mostly made of synthetic polymers (essentially food-grade plastics), sweeteners, softeners, and flavorings. The gum base itself, the chewy part that holds everything together, typically makes up about 30% of a piece of gum by weight, while sweeteners like sorbitol can account for more than half.
The Gum Base: Food-Grade Plastic
The ingredient list on a pack of gum usually just says “gum base,” which is a catch-all term that obscures what’s actually inside. The FDA allows a long list of synthetic polymers in chewing gum base, including polyvinyl acetate, polyisobutylene, and butadiene-styrene rubber. These are the same families of compounds found in rubber gloves, adhesives, and plastic films, though the versions used in gum must meet specific purity and molecular-weight standards.
Beyond the polymers that give gum its chew, the base also contains plasticizing materials (softeners) that keep it pliable. These include glycerol esters of rosin, a substance derived from pine tree resin, and synthetic terpene resins made from compounds found in pine oil. Small amounts of antioxidants like butylated hydroxyanisole (BHA) are added to prevent the fats and oils in the base from going rancid, capped at no more than 0.1% of the gum base.
Before Plastic: Chicle and Tree Resin
People have chewed on natural materials for centuries. Ancient Greeks chewed mastic gum, a resin from the bark of the mastic tree found in Greece and Turkey, both to clean their teeth and freshen their breath. In colonial America, Native peoples introduced settlers to the practice of chewing resin from spruce trees, and lumps of spruce gum became the first commercially sold chewing gum in the eastern United States in the early 1800s.
The direct ancestor of modern gum arrived in the 1860s, when chicle was brought to the U.S. from Central America. Chicle is a natural latex tapped from the sapodilla tree, which grows in the tropical rainforests of Mexico, Guatemala, and Belize. It gave gum a smooth, satisfying chew that spruce resin couldn’t match. Chicle remained the standard gum base until the mid-20th century, when synthetic polymers replaced it in most commercial brands because they were cheaper, more consistent, and easier to manufacture at scale.
Sweeteners Make Up Most of the Gum
If you’ve ever wondered why gum feels smaller after you chew it for a while, it’s because the sweeteners are dissolving. In sugar-free formulations, sorbitol alone can make up roughly 55% of the total weight. Xylitol is another common sugar alcohol, sometimes used alongside sorbitol or replacing a portion of it. These sugar alcohols do double duty: they provide bulk and body to the gum while delivering sweetness without promoting tooth decay the way regular sugar does.
On top of the bulk sweeteners, gum contains small amounts of intense sweeteners. Aspartame has been the standard for decades, used at around 0.3% by weight. Stevia, a plant-derived sweetener, is increasingly showing up as an alternative. Traditional gum with sugar uses sucrose or dextrose instead, though sugar-free varieties now dominate the market.
Flavoring and Acids
Mint, fruit, and cinnamon flavors come from a combination of natural and synthetic flavoring oils, typically making up about 1% of the gum by weight. The challenge for manufacturers isn’t adding flavor; it’s making it last. Flavor compounds dissolve in saliva quickly, which is why most gum loses its taste within minutes.
Fruit-flavored gums often include food acids like malic acid and citric acid to create that sharp, tongue-tingling sourness. Some manufacturers encapsulate these acids in a protective coating so they release gradually during chewing rather than hitting all at once and fading. Glycerin, usually around 14% of the formula, serves as a humectant that keeps the gum moist and helps distribute flavors evenly throughout the base.
How Gum Gets Made
Commercial gum production starts with heating the gum base to between 65°C and 95°C (roughly 150°F to 200°F) so it becomes soft enough to blend with other ingredients. The warm base enters a twin-screw extruder, a long barrel with rotating screws that mix everything together as the mass moves forward. Sweeteners like corn syrup are fed in at a lower temperature, around 29°C to 32°C.
As the ingredients travel through the extruder, the barrel is actively cooled to counteract the heat generated by mixing. The gum exits as a continuous warm slab at about 40°C to 51°C. From there, it moves to a rolling and scoring machine that flattens it to the right thickness and cuts it into individual sticks or pellets. Pellet gum gets an additional step: a hard candy shell built up through multiple layers of coating.
What Happens If You Swallow It
The gum base is indigestible. Your body doesn’t produce enzymes capable of breaking down those synthetic polymers, much like it can’t fully digest corn kernels or raw plant fiber. But the old claim that swallowed gum sits in your stomach for seven years is completely false. Gum doesn’t stick to your stomach lining or intestinal walls. It moves through your digestive tract the same way any other food does and comes out in your stool. Most people empty their stomachs within 30 to 120 minutes after eating, and swallowed gum follows the same timeline.
Gum and Microplastics
Because the base is made of synthetic polymers, chewing gum is technically a plastic product. Lab analysis of commercial gum has found that chewing releases microplastic particles, including polyolefins, polyterephthalates (PET), polyacrylamides, and polystyrenes, with polyolefins being the most abundant. This also explains why discarded gum is so persistent in the environment. Those gray spots on sidewalks are essentially blobs of plastic polymer that won’t biodegrade in any meaningful timeframe.
Natural and Biodegradable Options
A small but growing number of brands have returned to chicle as their base, marketing their products as “plastic-free” gum. Simply Gum, for example, uses natural chicle sourced from Central American sapodilla trees, combined with candelilla wax, organic cane sugar, and natural flavors. The chewing experience is slightly different from conventional gum. Chicle-based gum tends to be softer and loses its texture faster. But it biodegrades naturally, unlike its synthetic counterpart, and avoids the microplastic release that comes with chewing polymer-based gum.