Asked by Peter Bettings

The origin of stomach rumblings comes from muscle contractions and fluctuation. As food enters the gastrointestinal tract its walls squeeze the contents through the system at regular intervals to clear any potential buildup of food, gases and liquids. This fluctuation is known as the basic electrical rhythm (BER). The speed and force of the muscle fluctuations increases both in the presence of foodstuffs and also without them. In this latter case, the nerve receptors initiate a reflex generation of electrical activity, causing the muscles to contract and vibrate (ie rumble).

This myth stems from an old wives’ tale, stating that because of its sticky, rubberised texture, chewing gum is not digestible by the human stomach. In reality, there is no evidence that this is the case, with no recorded case of gum being permanently lodged within the stomach. In fact, modern scientific trials have shown that in most cases gum actually passes through the digestive system just as quick as any other foodstuff, with only a slight delay (mere hours) registered in a small percentage of cases.

Chewing gum’s sticky, rubber texture comes primarily from its base, which is produced from chicle – a natural latex product – or a synthetic rubber like polyisobutylene. Neither of these products have any proven side effects on the human digestive system.

On Earth, gravity pulls us towards the ground. However, the force you notice isn’t the downward pull of gravity, but the upward force of the ground beneath you. The ground pushes up on your feet, pushing up on your bones and organs. The sinking feeling in your stomach when on a rollercoaster or driving over a hill is caused by a change in force experienced by your organs.

When in freefall, every part of you is accelerating at the same rate, which gives you a similar feeling to weightlessness. There is no upwards force from the ground to cause your organs to be compressed, so they are floating inside of you, even though you are falling. Our bodies aren’t used to this change in force on our organs, which causes messages to be sent in the brain that something is amiss.

Damien Arness-Dalton, Science Museum

The main ingredient for chewing gum is the ‘gum base’ which is essentially a synthetic type of rubber. These gum bases are then mixed with sweeteners and flavourings (either natural or artificial) to make chewing gum. About 60-70 years ago, the gum base was commonly made from chicle, a milky white sap, which can be found on the sapodilla tree native to southern Mexico, Central America and the Caribbean.

Swallowing small pieces of gum is quite harmless as the gum should pass through your system like any other food. The sweeteners and flavourings will be digested but the ‘gum base’ cannot be broken down so all that happens is it will pass through the digestive system intact at about the same rate as the broken-down food.

Rik Sargent, Science Museum