With chewing gum, they reconstruct genome of young Neolithic 7:23

(CNN) -- If you're one of the many people who have swallowed a whole piece of gum by accident, chances are a question came to mind right after that unpleasant feeling.

How long will the gum stay there? There is a widespread idea that it will remain in the stomach for seven years after swallowing it, but this is not true.

"It's an elderly myth," says Simon Travis, Professor of Clinical Gastroenterology at the University of Oxford, UK. "I have no idea where the myth came from; I imagine it was raised because someone wanted to stop their children from chewing gum."

Swallowing gum is only harmful to the body if done in excess, Travis said by email, which is very rare. He explained that swallowing three or more pieces of gum a day would be considered excessive.

"If you swallow gum, it will go through your stomach, into your intestine and out unchanged at the other end," Travis said. "There are cases of chewing gum that lodges in the intestine of babies and even children if they have swallowed a lot, and then cause an obstruction. But in more than 30 years of gastrospecialty practice, I've never seen a case."

Dr. Aaron Carroll, distinguished professor of pediatrics and chief of health at Indiana University, has written several books in which he debunks myths about the body.

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Carroll agrees that swallowing gum doesn't hurt, but he wouldn't actively encourage it.

"It has no nutritional value," he says. "Chewing gum is made from sweeteners, flavorings and aromas. Base rubber is a mixture of elastomers, resins, greases, emulsifiers and waxes. So I wouldn't say it's healthy."

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Since when do you chew gum?

Before chewing gum was marketed and sold in today's packages, ancient people used it to quench thirst and hunger, according to Jennifer Mathews, a professor of anthropology at Trinity University in San Antonio, Texas, and author of "Chewing Gum of the Americas, From the Ancient Maya to William Wrigley."

The Maya chewed a substance called chicle, which comes from the sapodilla tree, common in southern Mexico and Central America, Mathews explains.

"Chewing gum is a natural latex that comes from a tree called a sapote boy or sapote," Mathews explained. "If you cut down a sapote boy tree, the latex starts oozing as a form of protection. It forms a barrier to protect the tree. You can tear it off the tree and start chewing it."

Similarly, the Pima Indians of what is now the United States chewed spruce sap for thousands of years before European settlers took up the habit and it was traded, Mathews explains.

When to worry about swallowing gum

Unless you have pain or swallowed a lot of gum, Travis and Carroll say you don't need to go to the doctor if you accidentally swallow a whole chunk.

"It's a theoretical problem," Carroll said. "In theory, you could get something big enough in a small child to cause an obstruction, but this is not something ordinary people need to worry about."

However, for people with problems in the gastrointestinal tract, or GI tract, which is a series of organs joined together in a long, twisted tube from the mouth to the anus, swallowed gum could cause problems.

"If things are open and there are no obstructions or narrowings, things will go smoothly," says Dr. Leila Kia, an academic gastroenterologist and associate professor of medicine at Northwestern University Feinberg School of Medicine in Chicago.

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"If there's very severe narrowing or inflammation for whatever reason, or if there's a motility problem where the stomach or colon isn't emptying as it should, then eating something like gum or something that can't be broken down can stay there and cause problems," Kia explains.

According to Kia, Crohn's disease is a common cause of inflammation of the gastrointestinal tract and can lead to its narrowing. He said doctors typically recommend a low-residue diet for Crohn's patients, which avoids certain foods such as raw fruits and vegetables, nuts and seeds, popcorn and chewing gum.

Some cancers and surgeries can cause this narrowing. "Certainly, if you swallowed a lot of gum, that could become a problem if you only have a small stomach or if you've rearranged the anatomy, which is essentially what happens when you have gastric surgery," Kia said.

Still, Kia has never removed gum from anyone's body, though it has removed dentures it believes were inadvertently swallowed.

Chewing gum