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The science behind chewing and brain health
New research suggests that thorough chewing does more than aid digestion-it may enhance memory, sharpen focus, and even lower the risk of Alzheimer's disease. While the concept dates back to early 20th-century nutritionist Horace Fletcher, modern science is uncovering surprising links between mastication and cognitive function.
From fad to fact: The legacy of 'The Great Masticator'
Horace Fletcher, known as 'The Great Masticator,' advocated chewing food until it liquefied-sometimes up to 722 times per bite. His extreme approach, dubbed 'Fletcherism,' promised economic savings (he claimed it could save the U.S. $19.5 million annually in today's money) and superior digestion. While his methods were excessive, experts now acknowledge some benefits.
"In some aspects, Fletcher was actually right," says Mats Trulsson, a professor of dental health at Sweden's Karolinska Institutet. Chewing thoroughly improves nutrient absorption, reduces calorie intake, and may even alleviate stress.
How chewing affects digestion and metabolism
Chewing initiates digestion by breaking food into smaller particles and mixing it with saliva, which contains enzymes like amylase. This process signals the gut and pancreas to prepare for food, explains Andries van der Bilt, a pioneer in oral physiology. Poor chewing can lead to bloating and inefficient nutrient absorption.
A 2009 study found that chewing almonds 40 times instead of 10 increased energy absorption by up to a third. Participants also felt fuller longer, with higher levels of satiety hormones like CCK and GIP. Similarly, a 2013 study showed that chewing pizza 40 times reduced hunger more effectively than chewing it 15 times.
The 'bite-brain axis': Chewing and cognitive function
Emerging research highlights a connection between chewing and brain health, dubbed the 'bite-brain axis.' Tooth loss and poor chewing ability have been linked to higher risks of Alzheimer's and dementia. A study of over 28,500 Europeans aged 50+ found that those with good chewing ability performed better on memory and cognitive tests.
"Chewing may act like a pump, increasing blood flow to the brain," says Trulsson. The hippocampus, critical for memory and often damaged in Alzheimer's, is connected to neural circuits involved in mastication. Studies also show that chewing gum can improve attention and alertness, though the effects last only 15-20 minutes.
Stress relief and mental well-being
Chewing may help reduce stress and anxiety. A study of nursing students found that gum-chewing for 30 minutes daily lowered stress levels before exams. Similarly, gum-chewing alleviated pre-operative anxiety in women undergoing surgery and children receiving IVs.
However, the evidence is mixed. Some studies found no effect on anxiety in pregnant women or those facing unsolvable tasks. Jianshe Chen, an oral processing researcher, notes that while chewing is a natural stress response, the scientific link remains "scattered."
Practical tips for better chewing
Experts recommend mindful eating-chewing slowly and thoroughly-to improve digestion and satiety. Textured foods like nuts, oatmeal, and whole fruits require more chewing than liquids or soft foods, which can aid weight management.
Trulsson's team is studying whether dental implants can reverse cognitive decline in patients with missing teeth. MRI scans will track changes in brain function over a year. "Wouldn't it be cool if rehabilitating dentition could rehabilitate the brain?" he asks.
Most researchers agree there's no magic number for chewing. "Chew normally until it feels right to swallow," advises van der Bilt. "Just enjoy your food."
