Doctor debunks the stomach-churning myth about an “indestructible” food

One minute you’re happily blowing bubbles with a chewy, sweet ball of gum, and the next — as if by disastrous magic — the colorful, minty glob slips down your throat and tumbles into the acidic depths of your stomach below.

And so legend has it, that’s where the gum will reside for the next seven years, unperturbed by your body's natural digestive enzymes. Or, as the parents of Megan Elias, historian, gastronomist, and associate professor at Boston University so loved to tell her, it may get stuck on the way down.

“I was told that if I swallowed gum it would stick to the cilia in my throat and I would choke!” Elias recalls for Inverse. “This slightly discouraged me from chewing gum.”

But as with most tall tales we’re told as children, the perils of swallowing chewing gum are far from scientific reality, doctor Nancy McGreal explains to Inverse. Rather, as Elias reveals, dietary and class standards may be at the root of this food myth.

Where does this myth come from?

Scientists have discovered ancient globs of chewing gum derived from tree pitch dating back as far as 5,700 years ago. The pre-packed and flavored chewing gum we munch today is a more recent innovation — gum as we know it originated toward the end of the 19th century.

One of the first to emerge on the scene was the gum created by William Wrigley Jr. (of Wrigley gum fame), whose gimmick of giving away pieces of gum along with large orders of the soap his company produced at the time eventually made him one of the richest men in United States by his death in 1932.

Chewing gum is not inherently dangerous, but it hasn’t always been inherently polite either. Noisily smacking away at your gum or blowing bubbles in classrooms is generally considered bad behavior, and in some societies, it is considered taboo to chew gum in public at all.

Reinforcing these masticatory manners has led to a historic discouragement of gum chewing and swallowing, Elias says. Another concern for parents, she adds, may have been the sugar content of gum. With 2 grams of sugar per stick of gum — unless you get the sugar-free kind — means that chewing packets of the stuff can have a negative effect on your dental health.

McGreal, who is a pediatric gastroenterologist, also suggests in a Duke health blog that telling children tall tales about how swallowing gum will mean it will stay in their stomachs for years may be a tactic by parents to keep children from swallowing other non-food items, too, like coins or Polly Pockets. As for the 7-years it allegedly takes to digest gum, McGreals says there’s no science to support that.

“People have a fascination with the number "7" which seems to be entrenched in some degree of mysticism, biblical references, and also luck in gambling,” McGreal tells Inverse. “It may be plausible that it could take 7 days to pass a piece of swallowed gum but certainly not 7 years.”

What happens if you swallow chewing gum?

Gum chewers can rest easy, McGreal says. Even though the globs are technically regulated as non-food items (or “nonnutritive masticatory substance”) by the FDA, our stomachs can’t tell the difference. At least, that is, when it comes to moving the stuff through your system after we swallow it down.

The human stomach generally empties every couple of hours and in that process, it will flush gum along with everything else and send it on its way through your small and large intestines — and eventually out the back door. While gum can generally make this journey without incident, it won’t be digested the same way as other foods because our bodies don’t manufacture the right enzymes to break down this rubbery substance.

“When an individual swallows gum, enzymes in your saliva and intestinal tract digest the sugars that give it the sweet taste,” says McGreal. “[But] our bodies do not possess digestive enzymes to specifically break down gum base and that is why it travels through the intestinal tract intact. A similar phenomenon is sometimes seen with corn kernels and other fibrous vegetables that are excreted in stool whole or intact.”

Ultimately, the whole process from start to finish should only take about 3 days, max. Not quite seven years then.

Is swallowing chewing gum dangerous?

If you swallow the odd piece of chewing gum throughout your life, McGreal says that’s unlikely to cause any damage.

“For most individuals, there is nothing really dangerous about swallowing gum and it will generally pass naturally,” she says. “The natural and artificial sweeteners in sugar-free gum can cause nausea, diarrhea, and headaches if swallowed in large quantities. Otherwise, medical interventions are not necessary.”

In her Duke blog, McGreal adds that “in all the upper endoscopies I have done in both children and adults, I have yet to see a wad of gum lying around in the stomach.”

There are, of course, exceptions to the rule. In a 2007 Scientific American article, pediatric gastroenterologist David Milov attests that he’s encountered several people with gastrointestinal blockages caused by chronic gum-swallowing. In one person, Milov says a piece of gum attached itself to a pile of sunflower seed shells in this person’s digestive tract and took on the appearance of a porcupine.

Yet despite these mishaps, gum swallowing is not a life-threatening condition and something that can be generally be solved over the course of a trip to the doctor, should you be so unfortunate to have gummed up your system as a result.

Do any foods take 7 years to digest?

Even if the folklore surrounding gum isn’t true, does any other food have such sticking power in the gut? Another no, McGreal says.

The longest an edible food may take to break down and be digested in your gastrointestinal tract is about two days. This is particularly true of complex proteins and fats, such as those found in meat products. All said and done, the stomach and intestines are pretty good at their job and efficiently process the nutrients from food, and rather excellent at discarding waste from the body.

If something you swallow can’t be digested (like gum or a penny) it will more likely than not still make an appearance downstream in just a few days...

Is it safe to chew gum?

Long story short, your gum-chewing habit isn’t likely to put you in serious trouble anytime soon, aside from perhaps potential cavities if you don’t switch to the sugar-free stuff. In fact, chewing gum has been linked to several benefits, including increased productivity and focus in some scientific studies.

One 2013 study published in the British Journal of Psychology involving 38 participants found that chewing gum may boost your ability to focus on cognitive tasks. A more recent review, published in 2019 in the journal Physiology & Behavior, found that chewing improves your attention span, particularly to “cognitively demanding tasks,” like memory tasks. Chewing may also keep you more alert for longer as you engage in these brain-taxing tasks, the review found.

In other words, chewing on a wad of gum may be an easy hack to better brain performance. Just remember to spit it out after you’re done cramming for that test.

CHECK, PLEASE is an Inverse series that uses biology, chemistry, and physics to debunk the biggest food myths and assumptions.

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