Chewing problems open the door to… dementia

If you want to have and maintain a healthy mind, it is important to take care of your teeth.

Increasing research in humans and animals shows that good chewing may stimulate the key brain structures responsible for memory and learning, and that dental problems may be related to the development of dementia later in life.

In the most recent of these studies, published last month in the scientific journal “Journal of Dental Research“, Japanese scientists fed young mice in development with powdered food and compared them with their peers that were fed with normal, hard foods.

As they found, the animals that did not need to chew their food had reduced development in the jaw and facial bones, as well as in the corresponding muscles. They also had impaired memory and learning abilities, because the activity of nerve cells in their hippocampus was reduced, as well as the creation of new connections (synapses) between them and the activity of a substance called BDNF, which plays a key role in memory. The hippocampus is the center of the brain that regulates memory and learning.

These findings suggest that “changes in chewing stimuli may affect neurogenesis and neural activity in the hippocampus, having negative impacts on cognitive functions,” the researchers note in their article. They add that “maintaining or enhancing chewing ability may be effective in preventing dementia and memory/learning dysfunction.”

“Chewing is an essential oral function related to physical, mental, and social health throughout life,” said the lead researcher Dr. Takashi Ono, professor at the Department of Orthodontic Science at the Tokyo Medical & Dental University (TMDU). “Older adults often suffer from chewing dysfunction due to tooth loss and weakening of the chewing muscles, while in children, chewing stimulation affects the development of the central nervous system and maxillofacial tissues.”

“Chewing plays many roles in health, according to current scientific data, as the way we chew can affect digestion, teeth, or even the shape of the face,” says Dr. Katerina Douma-Michelaki, DDS, PhD, specialist in Pediatric & Adult Orthodontics.

On average, we chew 800 to 1,400 times a day, while modern humans who eat more soft, processed foods require less chewing than those who eat many raw and hard foods.

Coordination of multiple centers

But how can chewing affect brain health? As Dr. Hideo Kawahara, former president of the Japanese Academy of Clinical Dentistry (ACD) explained at the international symposium on dentistry and orthodontics MegaGen to be held in Tokyo, the process of chewing food stimulates the brain’s vascular system, increasing blood flow, which can affect the entire body’s condition, including the brain.

Additionally, chewing is not just a mechanical movement, but involves all the senses, as when we eat, we see, smell, taste, hear, and touch the food with our mouth. This results in stimulation of the sensory centers in the brain, the centers that create our memories and preferences, as well as the feelings of reward or discomfort.

Moreover, because chewing requires the coordination of all the muscles in the mouth, as well as those in the upper digestive and respiratory systems (to swallow, we need to momentarily stop breathing), it activates an additional, complex sequence of mechanisms all regulated by the brain.

“Although chewing and swallowing are automatic processes that we don’t pay much attention to, they may affect us much more than we think,” said Dr. Kawahara.

What studies have shown

Specifically regarding the brain, clinical studies so far have shown that proper chewing may improve concentration and reduce the risk of dementia.

In one of these studies, scientists from the Department of Dentistry and the Aging Research Center at the Karolinska Institute in Stockholm examined tooth loss, chewing ability, and mental functions of more than 550 volunteers aged 77 and older.

As they reported in 2012 in the scientific journal Journal of the American Geriatrics Society, those volunteers who could chew hard foods comfortably were at a significantly reduced risk of dementia.

In a combined analysis, published this May in the scientific journal Archives of Gerontology and Geriatrics, Japanese scientists reviewed 33 clinical studies on chewing and mental functions, concluding that poor chewing may be an important risk factor for dementia or mild cognitive impairment, which often precedes dementia.

What you should do

Of course, “all these are correlations and do not prove causality,” clarifies Dr. Douma-Michelaki. “Until the matter is definitively clarified, though, make sure to do some things that are definitely safe for you: eat as many raw and hard foods as possible (e.g., raw vegetables and fruits), chew your food well, avoid too many pureed and watery foods, and, of course, strictly follow oral hygiene rules (including preventive visits to the dentist at least once a year).”

Finally, if you have damaged or crooked teeth, “don’t hesitate to see a specialist for immediate treatment,” she concludes.