What’s Really in Your Chewing Gum? The Answer Might hurt You

In the early 20th century, William Wrigley Jr. had a vision: to build an empire around a product designed for chewing. He successfully persuaded the U.S. Department of War to include his chewing gum in soldiers’ rations.

At the time, Wrigley made bold claims—chewing gum could quench thirst, curb hunger, and relieve nervousness. There was no scientific backing for these assertions back then. But in time, researchers found some truth to his claims. Studies later confirmed that chewing gum could help improve focus, reduce overeating, lessen thirst, and even support oral health.

Perhaps this is why humans have been chewing on natural substances for millennia—tree roots, resins, twigs, whale blubber, even materials derived from burnt bark.

Today, chewing gum is still widely marketed as a health-promoting product. You can find gums that promise to boost energy, deliver nutrients, ease anxiety, and even reduce joint pain. Scientists are even developing gums that may help protect against influenza, herpes, and COVID-19.

But here’s the twist: these modern, health-forward gums often contain an ingredient that is rarely associated with well-being—plastic.

When William Wrigley started his business, Americans were already in the habit of chewing gum. Back then, gum typically came as candy-coated balls or individually wrapped sticks. Its primary ingredients were natural, especially a substance known as chicle—a natural latex extracted from tree bark.

Chicle had been chewed by the ancient Aztec and Maya civilizations for hundreds, possibly even thousands of years. However, for mid-20th-century Americans, it posed a growing problem. The trees that produce chicle, known as chicozapote, grow slowly. Overharvesting could kill them, and cultivated versions of the tree yielded far less chicle than wild ones, according to Jennifer Mathews, an anthropologist at Trinity University and author of a book on chicle.

By the 1950s, chicle harvesters were struggling to meet demand. That’s when gum manufacturers turned to a new solution—artificial rubber and plastic.

Today, most commercial gums are made from a blend of natural and synthetic materials. If the ingredients list merely reads “gum base,” that’s typically a sign it contains synthetic polymers.

According to the U.S. Food and Drug Administration (FDA), gum base may include a variety of food-grade ingredients. While these may not be designed for direct consumption, they are considered safe to come into contact with food.

Some of these ingredients are things you’d never imagine putting in your mouth. For example: polyethylene, found in plastic bags and milk jugs; polyvinyl acetate, used in glues; and styrene-butadiene rubber, a component in car tires.

Confectionery consultant Gwendolyn Graf says that a typical gum base contains two to four kinds of synthetic plastic or rubber.

Ironically, it’s these very ingredients that enable many of the gum’s most desirable traits. “The features people like about modern chewing gum are mostly due to synthetic polymers,” Graf explains.

Polyvinyl acetate, for instance, helps gums form strong bubbles. “If your gum pops too easily when you try to blow a bubble, that probably means there’s no polyvinyl acetate in it,” Graf says.

Styrene-butadiene rubber gives gum its chewiness, helping it stay intact without sticking to your teeth. Polyethylene helps keep gum soft, preventing jaw fatigue from prolonged chewing.

In contrast, gums made purely from natural polymers often feel like they’re disintegrating in your mouth, Graf notes.

But these plastic-containing gums have their own form of breakdown—chewing gum has been linked to microplastic ingestion.

In December 2023, a U.K. study revealed that a volunteer who chewed gum for one hour and then spit into a test tube released over 250,000 micro- and nanoplastic particles into their saliva. That’s on par with the levels of microplastics found in a liter of bottled water.

In another study presented at a recent (though not yet peer-reviewed) scientific conference, a graduate student found increased levels of microplastics in saliva after chewing several commercially available gums—including ones labeled as “natural.”

So far, research into microplastic ingestion through gum chewing is limited. These two studies relied on saliva analysis from only two individuals.

Still, another line of research has found elevated levels of phthalates in urine after chewing gum. Phthalates are chemicals used to soften plastics, and they’re known to disrupt the human endocrine system.

Scientists are still working to understand how microplastics affect the human body. These particles can enter food through packaging, processing contamination, or through plants and animals that have already absorbed them.

As a result, microplastics have been found in human liver, kidneys, brain, lungs, intestines, placenta, and even breast milk.

But how exactly the body absorbs, distributes, and excretes these plastics remains unclear, says Marcus Garcia, an environmental health researcher at the University of New Mexico.

Lab studies on mice and human cells suggest microplastics can damage cells. Public health studies have also linked microplastic exposure to respiratory, digestive, and reproductive system problems—and possibly to colon and lung cancers.

Researchers are still trying to determine if microplastics directly cause disease, which types are most harmful, and how much exposure the body can tolerate before it starts to cause damage.

The answers to those questions could influence what we eat—and what we chew—in the future. For now, many experts believe it’s nearly impossible to avoid ingesting small plastic particles altogether.

In recent years, Americans have grown increasingly concerned about plastics in food. Many now avoid microwaving meals in plastic containers or drinking water from plastic bottles.

Yet chewing gum hasn’t drawn quite the same level of scrutiny.

Interestingly, chewing gum’s popularity has declined in recent years, although likely for reasons unrelated to microplastics.

To win back consumers, gum manufacturers are now rebranding synthetic gum as a health-forward product.

In a move that echoes William Wrigley’s original strategy—selling gum as a nerve-calmer and wellness tool—today’s companies are once again leaning into the idea of “therapeutic gum,” hoping Americans will embrace the health benefits and not focus too much on what the gum is actually made of.

But for those concerned about ingesting even more plastic, skipping chewing gum might be one of the easier lifestyle adjustments to make.