It's believed that there are ±45 essential nutrients that the body needs to perform normal bodily functions. The word 'essential' means that the body cannot manufacture them, so therefore they must come from outside sources. In addition to carbohydrates, fats and water that are required for proper metabolic function, there are at least 13 kinds of vitamins and 20 kinds of minerals. When food is consumed, it gets broken down for absorption and transported by the blood stream.
The human body cannot absorb any nutrients in our food unless there are digestive enzymes to break them down. That is why it is so important to have digestive enzymes. As we begin to age, in roughly ten-year cycles, our body progressively loses its ability to produce enzymes. At first, it may not be that noticeable, but later you will discover that you cannot tolerate, or even enjoy certain foods like you did before. In addition, a feeling of reduced stamina may accompany this. That is a clear indication that you could be low on enzymes.