Does Gum Really Take Seven Years to Digest?

Chew on this.

Our Middle School Mysteries series investigates childhood rumors you never bothered to fact-check yourself.

The worst part about chewing gum is getting rid of it. Rarely does the end of a good chew session coincide with proximity to a garbage can. This is when gum chewers must ask themselves the eternal question: To spit, or to swallow?

Judging by the number of old pieces of gum strewn about the planet, it seems most people prefer to spit. For some, this commitment to littering is born of convenience; for others, it comes from a fear — left over from grade-school — that gum takes seven years to work itself through the digestive tract.

Seven years is a long time to be cursed with esophageal bad luck, so we decided to investigate whether or not there’s any truth to this middle school mystery.

A brief history of gum

People have been chewing gum for over 9,000 years: Evidence suggests that early humans in northern Europe chewed on birch bark tar for entertainment and medicinal reasons. Other cultures used gum-like substances to quell hunger and thirst, clean their teeth or freshen their breath.

Doctors don’t know how the gum-chewing rumor began, but they are quick to debunk it. In an interview with Scientific American, pediatric gastroenterologist David Milov says if this old wives tale was true, it would mean “that every single person who ever swallowed gum within the last seven years would have evidence of the gum in the digestive tract.”

Thankfully for the people administering colonoscopies, this does not appear to be the case.

So where does swallowed gum go?

Like bad news, gum is hard to digest. Your body breaks down components like sweeteners, but the gum’s elastomers — natural substances with elastic properties — pass through the body and emerge largely intact.

This is not to say that swallowing your gum is a good idea: A recent study published in the journal ScienceDirect claims that many gum recipes include nanoparticles of titanium dioxide which is dangerous when consumed in large quantities. You can find titanium dioxide in products like toothpaste, candy, chocolate and mayonnaise — so some amount of ingestion is more or less unavoidable. Still, the study cautions that too much of the stuff may impair the body’s ability to soak up essential nutrients and fight off infections.

Lest you feel inclined to test the body’s ability to digest gum, Milov offers some cautionary tales: In the 1998 magazine Pediatrics, he describes two children who repeatedly swallowed their gum, became very constipated and had to have the gum extracted rectally. In another episode, doctors discovered a one-year-old had swallowed four coins and a piece of gum and that the gum had fused the coins together, creating a mass in her gut.

So there you have it: In the case of spitting versus swallowing, spitting is grosser, but at least it won’t require a rectal extraction.