While it’s widely known that chewing more improves digestion, research suggests it can also boost our brains and even help fend off Alzheimer’s.
For once chewing a shallot 722 times before swallowing it, Horace Fletcher was dubbed “The Great Masticator”. The American self-taught nutritionist believed food should be chewed “until it is completely liquefied” and it “practically swallows itself”. Fletcher even estimated that vigorous chewing could have saved the US economy of the early 20th Century more than half a million dollars a day (roughly $19.5m in today’s money), because the average person would have ingested half a pound (227g) less food daily.
Fletcher’s doctrine may have been a little extreme, “but in some aspects, he was actually right”, says Mats Trulsson, professor in the department of dental health at the Karolinska Institutet in Sweden.
Chewing more can provide a wide range of health benefits, from improving digestion and helping people consume fewer calories to alleviating stress and anxiety and improving cognition by solidifying memory skills and boosting attention span. As there is a correlation between tooth health and Alzheimer’s disease and dementia, some experts argue that improving patients’ dental health could even help reverse mental ageing.
The prehistory of chewing
Like most animals, humans have “had teeth and jaws for millions of years,” says evolutionary and ecological biochemist Adam van Casteren at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. But they’ve gone through many changes throughout prehistory.
The earliest hominins, who lived roughly six to seven million years ago, had teeth similar to those of apes today; especially helpful for eating “lots of large, fleshy fruit” abundant in the forest habitats that our early ancestors lived in, says Van Casteren. But as rainforests gave way to more woodlands, open habitats and even savannah-like ecologies, hominins had to contend with “more mechanically challenging foods”, says Van Casteren, such as seeds, nuts, and tubers. So they evolved to favour an increase in molar size, with bigger jaws and faces to house all those teeth, alongside the larger muscles needed to power them.
The theory is that chewing works like a pump, pumping blood to the brain – Mats Trulsson
With the development of tools, food processing, and agriculture, as well as fire to cook food, we also stopped needing such lengthy bouts of mastication, explains Van Casteren. Today, humans spend roughly 35 minutes chewing every day, compared to 4.5 hours for our closest ape relatives, chimpanzees and bonobos and 6.6 hours for gorillas and orangutans.
Despite these evolutionary changes, the purpose of chewing remains the same. “We mammals are such complicated chewers because we want to get as much energy out of our food to power our warm-blooded metabolisms,” says Van Casteren.
Breaking food particles into smaller pieces increases their surface area, which means digestive juices can act on them more efficiently
