Most of us don’t think twice about it, but chewing — mastication — has implications for our health.
The way we chew, for instance, can alter our digestion, teeth and even our face shape. And new research suggests how often we chew could even affect our brain power.
Here we reveal what scientists and medics now know about this instinctive act …

THE TRUTH ABOUT CHEWING
We've all heard the dictum about chewing each mouthful 20 times before swallowing, but actually how many times we should chew depends on what we’re eating, says gastroenterologist Dr Nick Read, chief medical adviser for charity The IBS Network.
‘The Victorians thought you needed to chew food 14 times but we generally wait until it feels right and then swallow — it’s intuitive.’
He says that because our diet has become softer, thanks to all that processed food, we now don’t need to chew for so long.
However, raw fruit and vegetables, and meat, demand more chewing. ‘If you don’t, lumps of food will pass through your digestive system and not be completely absorbed,’ says Dr Read.
On average, we chew 800 to 1,400 times a day.

GUM CAN CHANGE YOUR FACE
When we chew, we use the masseter muscles in either side of the jaw. People who chew gum throughout the day can find the over-activity makes their masseter muscles ‘grow’.
‘This can make the patient’s face look very square,’ says Luke Cascarini, consultant oral and maxillofacial surgeon from North West London Hospitals and West Middlesex University Hospital.

OR AFFECT YOUR MEMORY
While the evidence is mixed, it’s thought chewing gum may stop you forming some kinds of memory, says Professor Andrew Smith from Cardiff University, a specialist in health-related behaviour.
‘Many aspects of memory rely on using sub-vocal rehearsal (when you repeat words to yourself in your head) and it’s difficult to do that while chewing because it’s a competing activity — but this area needs more research.’

OR WAKE UP YOUR BRAIN
That’s the suggestion from a study by the National Institute of Radiological Sciences in Japan, just published in the journal Brain and Cognition.
When participants were put through a number of tests, those who were chewing gum had 10 per cent faster reaction times compared to those who weren’t.
Using functional MRI scans, the researchers found that chewing affected eight parts of the brain — most of which are involved in executive function (actions) or motor-related functions, explains Dr Duncan Banks, a director of the British Neuroscience Association. ‘Those areas seem to light up more when people chew gum.’
There is robust evidence that chewing gum increases alertness, helps us to sustain attention and improves reaction times, says Professor Smith.
‘Chewing stimulates the trigeminal nerve, which stimulates part of the brain responsible for alertness. And we know that chewing increases heart rate, which in turn increases blood flow to the brain.
‘People who chew gum report increased productivity at work, which fits in with what studies show in the lab,’ adds Professor Smith, whose work in the past has been partly funded by chewing gum manufacturers.
In a study at Cardiff University, chewing gum was found to improve performance when people were struggling to pay attention while completing monotonous tasks. But it made no difference when they were operating at normal levels.

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