FYI: chewing gum is so hard to clean up, Singapore banned the sale of it in 1992. How did our love-hate relationship with gum develop and what really happens if you swallow it?

Chewing gum originated with the ancient Greeks, who masticated the sticky stuff obtained from the bark of the mastic tree, a shrub-like plant found in Greece and Turkey. Grecian women chewed it to keep their teeth clean and to sweeten their breath.

Chewing gum is made from a gum base mixed with flavouring and sugar. While traditional gum was based on latexes - vegetable products such as chicle, spruce and mastic - modern bases are waxes such as paraffin wax and beeswax. These days, chewing-gum manufacturers use petroleum-based polymers instead of chicle.

In large amounts, sugar-free gum, whether swallowed or chewed, can cause digestive problems. The sugar substitutes (hexitol, sorbitol and mannitol, to name a few) found in such gum are not absorbed but passed into the small intestine and colon and can have a laxative effect or cause diarrhoea.

Over the years, chewing gum has been credited with various positive effects on health and brain function. While it has never been scientifically proven whether it aids concentration, studies have suggested chewing gum helps improve memory and brain performance. One theory is that the act of chewing raises the heartbeat, pumping more oxygen and nutrients to the brain. Another is that it triggers the production of insulin, which stimulates a part of the brain involved in memory.

Gum is even said to speed recovery after bowel surgery. Researchers believe that chewing may stimulate the same nerves as eating, promoting the release of hormones that activate the gastrointestinal tract.

Chewing gum after meals helps to stimulate the production of saliva and the overall salivary flow. Saliva helps to wash away and neutralise the acid produced by bacteria in plaque. This acid is responsible for dental decay and bad breath.