Our parents have told us plenty of stories about what will happen if we eat certain things.

There's the watermelon that will grow inside us if we swallow the seeds, or the blockage we'll get if we swallow our chewing gum.

To our knowledge, no-one yet has sprouted a watermelon, but what about a gut blockage from too much gum?

Chewing gum, which has been around since the Stone Age, is made up of a gum base and modern ingredients including fats, emulsifiers, waxes, antioxidants, fillers, colourings, flavourings, preservatives and sweeteners.

Early chewing gums were made from a base of tree resin, but nowadays the gum base is most often synthetic, and the gum tastes a whole lot better.

Triggering peristalsis and enzyme activity

When you first start chewing, your body is tricked into thinking it's expecting food and prepares for digestion.

Your salivary glands are stimulated, releasing saliva into your mouth.

Enzymes then start to digest the gum's more soluble ingredients, like the sugars, but the gum base remains largely undigested.

Once the flavour is gone, you're ready to get rid of it and rather than spit the gum out, you may decide to gulp it down.

Peristalsis — the wave of coordinated muscle contractions that sweeps our food from one end of the gut to the other — then takes over.

Basically, your body will treat the lump of gooey gum the same way it treats anything it can't digest.

It carries the undigested mass of gum down through the oesophagus into your stomach where it churns for a few hours before travelling along your intestines to your rectum and then down the toilet.

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Spit, don't swallow chewing gum

Paediatric gastroenterologist at Sydney Children's Hospital Nitin Gupta says for most people, swallowing gum is not a problem — unless you do it repeatedly over a long period of time.

He says the intestines are really not that sticky because the gum travels easily along with bile, pancreatic enzymes and other fluids.

"Lots of people swallow gum but complications are pretty rare," Dr Gupta says.

"[But] if it starts off as a small lump and you keep on swallowing, the gum can stick and it can grow like a snowball."

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Lots of chewing gum in your stomach could result in a non-digestible lump called a bezoar.

One of these was an 18-year-old Israeli woman whose case was reported in a 2004 medical journal.

She presented with stomach pain and after telling doctors she'd been regularly chewing and swallowing five pieces of gum a day for several years, they found her stomach jam packed with a large blob of undigested chewing gum.

Her doctors had to first break up the mass, then use a tiny net to remove it, bit by bit.

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Discourage the kids from swallowing

Dr Gupta advises parents to ensure their children know not to swallow gum. ( ABC Life: Daniel Mee )

Young children, with their small gastrointestinal tracts, are more likely to swallow chewing gum — and other small objects, which combine with the gum to form an even bigger bezoar.

Because children's intestines are narrower than adults', a bezoar is more likely to get stuck.

A handful of cases involving young children under the age of five was published in the American journal Pediatrics with several common themes.

Most had been given multiple pieces of chewing gum a day as a reward for good behaviour, which they'd subsequently swallowed.

Two of the children had to have resulting blockages — which were still stretchy — manually removed from their rectums.

If your child has swallowed gum, Dr Gupta has the following advice:

If your child is constipated and you know they've swallowed gum, mention it to your GP at your next visit

If your child is constipated and you know they've swallowed gum, mention it to your GP at your next visit If swallowing gum is accompanied by lots of drooling, or severe discomfort or uncontrolled vomiting (yellow or green), take your child to the emergency department ASAP as this may indicate a blockage.

Better still, Dr Gupta advises, is preventing these rare situations in the first place and ensuring your children know not to swallow their chewing gum.

This is general information only. For detailed personal advice, you should see a qualified medical practitioner who knows your medical history.

This story, which was originally written by Anna Evangeli and published by ABC Health and Wellbeing, was updated in 2019.