Functions of our digestive tract in producing digestive juices and enzymes can be measured with an impressive numbers. For example, an average daily production of saliva containing alpha-amylase is 1 to 1.2 lit. That amount of saliva is needed day-in-day-out just to initiate the digestive process. Equally impressive are the calculated amounts of the gastrointestinal digestive juices and fluids, produced in the body to sustain the digestive process. This silent work of our digestive tract is not appreciated by us other than by feeling well and fit. However, this indispensable function of the digestive tract ages like rest of the body does, and production of the digestive juices and enzymes declines with age.
In addition, there are numerous nutritional and dietary factors, as well as disease conditions that deprive the digestive process of enzymes and their digestive capacity. It is estimated, for example, that exposure of the food to prolonged cooking in 47.8° C destroys entire content of enzymes that may be otherwise present in raw food.