Enzymes are a group of proteins created by the body that act as catalysts in the digestive tract to break down foods or throughout the rest of the body to assist in either the creation of useful materials (such as hemoglobin), the destruction of harmful ones (such as alcohol) or even turning body tissues into energy (such as those that help convert protein to urea when required to produce energy). Although the enzyme isn't chemically changed by the processes it assists, they are constantly created and destroyed by the body.It can cause ADHD.