Health Information and Nature Interface
Mastication and Health Care
Shigeru SAITO D.D.S., Ph.D.
Director, Japanese Society for Mastication Science and Health Promotion
*We are in the age of choosing the path of our death.
Diseases resulting from lifestyle choices and dementia have become the main causes of death in Japan, while the incidence of infectious diseases has drastically decreased. The reason for disease today is mainly due to changes in our lifestyle i.e., eating, sleeping, exercising and resting. It is quite difficult to correct. Furthermore, the change in the family environment may have adverse effects on the future health of our children.
*We need to start monitoring ourselves.
In the 21st century, medicine needs to change its paradigms from cure to care and from reaction to prevention. This will not diminish the importance of modern medical treatment, but it does mean we need to develop multi-purpose and function analyzing wearable computers which can accurately detect various physical abnormalities before we become ill. To achieve this, we need to correct our bad living habits throughout our lives.
First of all, I would like to introduce to you the importance of mastication. Mastication is not only the chewing and grinding of food, it is also related to the prevention of diseases that result from adverse lifestyles and dementia, and to the activation of many bodily functions.
*Mastication signals the satiety center.
The human metabolic rate increases one to two hours after a meal ends. This energy production is divided into two phases. Phase 1 occurs 40 minutes after a meal and phase 2 occurs 40 to 120 minutes after a meal.
This increased metabolism, especially in phase 1, signals the brain to activate the satiety center. From this we can infer that less chewing decreases the intensity of this signal and leads to obesity because of overeating. Chewing food completely can therefore be an effective method of controlling one's weight.
*Chewing well enhances digestion.
When food is completely chewed into small pieces, the total surface area of the food increases and digestive enzymes can more effectively decompose it.
The human body is powered by eating non-human organisms. Digesting food also means breaking down the allergens that foods contain. Therefore, enhancing digestion by completely chewing may prevent food allergies and atopic dermatitis, which is caused by antigen-antibody reactions.
*Mastication enhances brain activity.
Photo 1 shows a mouse brain before and after eating. Not only eating activates the cerebral cortex (the outer part of the brain) and the brain stem (the inner part of the brain), it also activates areas throughout the brain (the change of colors from green to yellow to red indicates more activity). This figure shows that the hippocampus, which directs the satiety center and memory, is also activated.
Chewing well activates the hippocampus and enhances memory, i.e., enhances brain activity.
*Mastication prevents dementia.
The function of the oral cavity declines as dementia worsens. When the human brain was investigated during mastication in someone who chews well, the motor area in the cerebral cortex became highly activated. This indicates a correlation between oral cavity function and dementia.
There is also a report that incipient memory defects worsened when the teeth of a mouse whose aging was accelerated were removed.
Therefore, it may be possible to arrest the effects of dementia due to aging by chewing well.
*Mastication strengthens the jawbone.
Bone tissue consists of mineralized salts and organic stroma. Mineralized salts are comprised mainly of calcium and phosphorus, while stroma consists of protein.
Stromata are made by osteoblasts. Osteoblasts are activated by exercise and produce more stromata.
The arm and leg bones are strengthened by exercising, likewise the jawbone is strengthened by chewing. Strengthening the jawbone prevents Periodontist and temporomandibular joint arthritis, and is also related to correct vocalization. Photo 2 shows X-ray photographs of the jaw of a person of the Jomon period (2,400-12,000 years ago) and that of a person of today. These photos indicate that people of the Jomon period even used their 3rd molar teeth, while people today have weaker jaws, and 3rd molars are often impacted.
*Mastication strengthens the facial muscles and bones and prevents wrinkles.
Weakening of the facial muscles and bones is one reason why wrinkles form on the face and around the mouth. Those who chew well may look younger because chewing keeps facial muscles and bones stronger.
*Mastication prevents bad teeth.
Salivary flow helps prevent the accumulation of bacteria in the mouth. Since saliva is secreted by mastication, chewing well effectively prevents tooth decay.
*Mastication enhances taste.
It is commonly known that saliva includes gastin, an enzyme that enhances tastebud sensitivity. Gastin enhances tastebud sensitivity by bonding with the zinc inside the food. An example of using this sensitivity is the Sommelier, who eats a piece of hard bread before tasting food in order to sharpen his or her sense of taste.
*Mastication prevents cancer.
Lactoperoxidase in the saliva reduces superoxide production from carcinogens.
*People today don't or can't chew correctly.
In my research I measured the number of times people chewed their food and the time required to eat a meal. I compared these findings for various eras. Figure 1 below shows that people today chew their food far less than in the past.
Meals are not just for enjoying good food and taking in nutrients. In traditional Japanese culture, good mastication has provided good health for each member of the family. Today many people eat their meals alone. This is an example of how the role of the Japanese family has begun to lose its importance in bringing up healthy minds. For the 21st century of health care, let's start with our mouths.