Chewing of food. When you put food in the mouth cavity tongue receptors (taste buds) send a signal to the brain to secrete certain enzyme consistency by the three pairs of salivary glands which every person is equipped with. Primary decomposition of sugars in the composition of ingested food is done right here in the mouth. Saliva must be in sufficient quantity because it is the first protective barrier against disease-causing (pathogenic) microbes that come from food into our body.
How to produce more and better saliva? This is achieved by prolonged chewing and grinding of the food between the teeth. In this process the muscles of the upper and lower jaw massage salivary glands and these secrete a sufficient amount of its contents into the mouth. The importance of continuous and adequate chewing of the food is expressed in two other particularly significant facts. People who do not chew enough are likely to develop benign cancer of the parotid salivary glands. Again here is in force a general physiological principle that when certain organ is rarely used it becomes undeveloped and with degraded performance. Without a joke I must say that for most people this organ is the brain. Reduced functionality of the parotid glands as well as of all endocrine glands leads to hypoxia and apoptosis. Well known mechanism.
Another aspect of the chewing is related to the further process of digestion which takes place in the stomach. If we hastily swallowed the food crushing it just as much as to ease its passage through the oesophageal tube then it falls into the stomach to pieces that have very small total surface. Gastric juice (hydrochloric acid and pepsin) and the enzymes cannot tear the food more but only to carry out biochemical catabolic (degradation) reactions on its surface. They do not act in depth. It is the crushed to a slurry state food in the mouth the one that provides gastric juices the greatest possible surface on which these can act to be reached the best degradation in the stomach. If the food is not well ground extraction of nutrients is weak and rotting begins in the stomach which causes ulcerative processes which in turn are again a basis for the development of hypoxia.