The word "Enzyme", in Greek, means exist in "zyme". Enzyme exists in all the bodies of living animals and plants, is a kind of substance with special biological activity consisting of amino acids. It has strong catalytic effect for many organic chemical reactions and complex reactions in organisms.
It is an essential material to maintain the normal function of organism, digest, absorb nutrients, repair tissues and other life activities. Not only for human beings, but for other organisms, the existence of life depends on the role of enzymes. If there is no enzyme, biochemical reaction will not be carried out, nutrients can't be digested and absorbed. Without enzyme, five major nutrients (carbohydrate, lipid, protein, vitamins and minerals) will become useless to the body and life will be stop. This is why enzymes are crucial in the sustenance of life on earth.