An important first step
At the most basic level, chewing breaks food down into small particles and moistens them with saliva so that they can be easily swallowed. “It’s the first phase of digestion,” says Andries van der Bilt, a pioneer in the field of oral physiology and chewing, who worked as a researcher at the University Medical Center Utrecht in the Netherlands for over three decades.
Not only does chewing increase saliva production and the amount of digestive enzymes like amylase that help break down food, it also triggers the gut and pancreas to secrete juices that will help process food further, too. “If you don’t chew, the gut is not prepared to handle food,” says Trulsson.
The act of breaking food particles into smaller pieces also increases their surface area, which means digestive juices can act on them more efficiently, says orofacial neuroscientist Abhishek Kumar, who works with Trulsson at the Karolinska Institutet. This is important for gut health. Bigger particles tend to linger in the gut longer, giving microorganisms more time to ferment them. This causes “feelings of bloatedness, fullness, constipation, and other symptoms”, Kumar says.
Improving absorption and feelings of fullness
The act of chewing helps release nutrients in food, allowing our bodies to absorb them more effectively. In a 2009 study, for instance, 13 healthy adults were asked to chew a small handful of almonds 10, 25, or 40 times. When researchers collected samples of participants’ poo, they discovered that the more people chewed, the less fat they excreted, suggesting that the absorption of energy from the nuts was up to a third higher. (In the early 1900s, in fact, Fletcher believed chewing more helps produce poo of superior quality – “quite dry” and smelling of a “hot biscuit”.)
What’s more, chewing 40 times left participants feeling fuller for longer. A separate 2013 study echoed this satiety link: when 21 participants chewed a chicken-nugget sized slice of pizza either 15 or 40 times before swallowing, those in the latter group experienced a significant reduction in hunger. They also had higher levels of CCK and GIP, two hormones that coordinate digestion in the gut, alongside suppressed levels of the “hunger hormone” ghrelin.
Fletcherism
So-called “Fletcherism” became a curious diet fad that swept through parts of Europe and the US in the 1900s and was practiced by many notable figures. Some Asian cultures also espouse good chewing, including traditional Chinese medicine. Japan’s health authorities once even introduced a Kamingu 30 campaign, encouraging citizens to chew every bite 30 times before swallowing.
Chewing more means you’re also likely to consume less food, according to two separate meta-analyses that reviewed nearly 50 studies.
That’s because it takes around 20 minutes for the body to adjust its production of hunger-related hormones and send signals to the brain that you’re full – and chewing buys you more time. It’s one reason why so many dieticians and doctors advocate slow and mindful eating over wolfing down a meal, especially if you’re trying to shed some pounds. A survey of 92 children in Brazil found that those who were obese “performed fewer mastication sequences and ate faster” compared to children of normal weight.
In a survey of 28,500 people aged 50 and over, people with good chewing ability performed better on a battery of cognitive tests
