Swallowing chewing gum could leave you with a bizarre and distressing medical condition, experts warn.

It can accumulate in the digestive system and harden, forming a 'stony mass' called a bezoar, they say — and chewing other indigestible substances, such as hair, can also increase the risk. 

In a case report published by Ecuadorian medics this month, a 24-year-old woman underwent a procedure to have a colossal 16in mass of hair, roughly the size of beach ball, removed from her stomach.

In the UK, there was a similar case of a seven-year-old girl from Newcastle who had a cricket-ball sized mass of hair removed from her stomach, according to Dr Dan Baumgardt an expert pharmacology and neuroscience at the University of Bristol.

And while eating vegetables and fruit is typically good for you, occasionally bezoars can form out of the indigestible parts of these foods like cellulose. 

Writing for the website, The Conversation, Dr Baumgardt said persimmons, particularly unripe ones, had a tendency to form bezoars due to their high tannin, a chemical naturally found in plants, content. 

But Dr Baumgardt added other foods and even non-foods also cause their formation — although, overall, cases were rare.

'Fruit and vegetable fibres, milk, medicines and gums (such as swallowed chewing gum) can form an indigestible mass in the stomach, while the ingestion of inorganic materials such as paper, polystyrene and plastics can also cause bezoars,' he said.

The compulsive consumption of non-edible items such as hair, paper, sand is medically called pica.

Young children, as well as adults with learning disabilities, are among the most frequent people to have pica but adults under mental strain or duress or with a deficiency of iron or zinc in their diet can sometimes also develop it. 

Pregnant women can also develop pica in what is believed to be a reaction to their body seeking certain types of nutrients. 

Dr Baumgardt said while many bezoars take on a stony appearance some, particularly those made from hair, can look more like a 'plait', giving rise to the term 'Rapunzel syndrome' named after the fairy-tale princess with long hair. 

Bezoars can lie silently in the digestive system for years as, providing they do not block or obstruct the normal function of the organs, they cause no symptoms that could alert medics or family members to their existence. 

But they can cause a host of problems if they do so, including nausea, abdominal pain, vomiting, ulcers and even internal bleeding. 

Dr Baumgardt said options for removal in these circumstances include an endoscope — a tiny tool attached to a flexible camera — if it is small enough.

Larger bezoars may require swallowing a solution to dissolve the material it is made from, or surgery. Options for this larger depend on the material ingested and where exactly the bezoar is located in the patient.

One substance often used to soften bezoars for further intervention are dark sodas like Coca-Cola or Pepsi.

According to an article published in Practical Gastroenterology in 2021 the slight acidity from the sodas and the carbon dioxide aids breaking up some types of bezoars.

This typically done by giving a patient three litres to consume in 24 hours.

While systematic medical reviews of the technique have found using sodas likes this is only successful 23 to 60.6 per cent of time, depending on the type of bezoar, the low cost and low risk nature of the intervention means it is often attempted. 

Dr Baumgardt advised people worried about or prone to bezoars to avoid the following foods and behaviours. 

'Avoid higher-risk foods such as persimmons, celery, pumpkin, prunes, and sunflower seed shells – and chew your food thoroughly before swallowing. Avoid swallowing indigestible nonfood items including hair, and seek medical advice if you’re concerned about the condition pica,' he said. 

Estimates of bezoars in the population vary but they are considered very rare.

Some studies put the rate in the population at between 0.07 to 0.4 per cent of the population, roughly between one in 250 people or less than one in a 1,000. 

Others state most centres which specialise in gastroenterology, treating disease of the digestive system, will only see on average 2.5 cases per year, those this can rise to 16.5 per year in nations with high consumption of foods like persimmons.