As a child, you heard the familiar threat from your mother: if you swallow your chewing gum, it will be stuck in your stomach for seven years. And while you hate to dispute your mother's wisdom, most adults probably have trouble swallowing that warning. And for good reason—it's not really true. While it’s generally a good idea to spit out your gum when the flavor runs out, swallowing it occasionally is fairly harmless in small pieces. Gum passes through your system pretty much just like other food, exiting the body in the same way.
Evidence for the Health Claim
Chewing gum is made of the following main ingredients: a natural or synthetic gum base, glycerin, vegetable-oil based compounds, sorbitol and mannitol or saccharin, preservatives, flavorings, and colorings. While the majority of these can be easily digested, the gum base can’t be broken down, so it passes through the digestive tract and out the body intact.
Because the gum base can’t actually be digested, there have been documented cases of swallowed chewing gum causing intestinal obstruction. Pediatricians at the Nemours Children's Clinic Division of Gastroenterology and Nutrition describe two unrelated cases of children suffering from chronic constipation , which could not be attributed to diet or dehydration. The physicians extracted stools from the children and found that they were “stretchy” and "taffy-like" and were actually masses of chewing gum that had, well, gummed-up the system. Upon conversation with parents, the physicians learned that the children had been chewing—and ultimately swallowing—between five and seven pieces of gum each day.
Evidence Against the Health Claim
Chewing gum has been part of human culture since at least 7,000 BC, the approximate date to which masses of prehistoric tar marked with teeth imprints can be traced. The Greeks, North American Indians, and other people indigenous to North America have all chewed gum for millennia, it is believed. The first patented chewing gum hit shelves in the US in 1869.
Today, chewing gum comprises a hefty portion of the $21 billion American candy industry. Yet gastrointestinal illnesses attributed to chewing gum appear to be few and far between. Since gum is typically chewed in small pieces, a single swallowed piece will travel the expected digestive path and pass—primarily intact—in the stool in just a few days time.
Documentation of intestinal blockages due to chewing gum seem to point only to a danger in swallowing excessive amounts of chewing gum repeatedly, as opposed to swallowing a single piece occasionally. Although the gum base itself is indigestible, a small piece of chewing gum can pass easily through the digestive tract in the same time it would take digestive waste to travel the same path and be eliminated.
The seven-year myth may have sprung from a misconception of gum’s digestibility based on the look and feel of gum. After all, it doesn’t dissolve in your mouth like other foods. Or, maybe it was mom’s clever way of scaring you into not swallowing your gum and freeing up your mouth for another piece!