Study Shows Chewing Slowly Not Only Aids Digestion but Also Helps Delay Cognitive Decline
The BBC (British Broadcasting Corporation) reported that a large survey covering 14 European countries and more than 28,500 people aged 50 and over found that people with better chewing ability and more retained natural teeth generally performed better on cognitive tests such as vocabulary memory, verbal fluency, and calculation.
The scientists involved believe this may be related to neural connections between the masticatory system and the brain's hippocampus. The hippocampus is responsible for learning and memory and is also one of the first brain regions affected in Alzheimer's disease. Some studies have found that blood flow in the brain increases somewhat when chewing harder foods.
These scientists have proposed the “bite-brain axis” theory, and some scholars have accordingly proposed a “blood pump” theory, holding that chewing may promote cerebral blood supply and thereby help maintain cognitive function. Other studies have shown that chewing may briefly increase alertness and concentration and may reduce anxiety and stress-related markers.
These latest studies are very interesting. Chewing slowly has long been a lifestyle habit people recommend; for a long time we have only noticed the help it brings to digestion, and have not noticed its role in protecting brain function and delaying cognitive decline. This study may be called a refreshing new approach.
But on reflection, these studies are not without reason. Chewing slowly is also “using the brain,” except that this kind of “brain use” differs somewhat from what we usually mean by it.
Human chewing relies mainly on four pairs of masticatory muscles working together: the masseter, temporalis, medial pterygoid, and lateral pterygoid. These muscles attach between the mandible and the skull, are innervated by the trigeminal nerve, and are responsible for the biting and grinding of food and for the various movements of the mandible. Their coordinated movement does indeed help improve cerebral blood circulation. Elderly people who chew slowly have a lower risk of cerebral infarction, which in turn lowers the risk of dementia.
So to what extent should we chew slowly? It is generally thought that spending about twenty minutes on a main meal is most appropriate; this brings the total daily chewing time to about an hour across the three meals. This amount of movement time is suitable for the brain.