The digestive process is complicated, with some of the enzymes requiring an acidic environment and others requiring a more basic environment to function. Your body creates the enzymes it needs, so you don't need to worry about eating foods that contain natural versions of these enzymes.
Beginning the Digestive Process
Food first encounters digestive enzymes in your mouth. Your saliva contains amylase, which is an enzyme that helps break down starches and sugars. Once your teeth and saliva partially break down your food, you swallow it and it travels down the esophagus to the stomach for further digestion.
You need an enzyme called pepsin to digest protein. This enzyme is formed when a substance called pepsinogen is mixed with stomach acid because it requires an acidic environment to work. Without stomach acid, you can't digest protein. Once the protein is partially digested, food is released from the stomach into the small intestine, where the majority of digestion and absorption takes place.
Enzymes in the Small Intestine
The small intestine contains other digestive enzymes produced in the liver, pancreas and small intestine. These enzymes are necessary for turning the food you eat into energy and releasing the nutrients it contains so they can be absorbed into your bloodstream. Once the food leaves the stomach, the stomach acid that travels with the food is neutralized because the enzymes in the small intestine require a more basic, less acid environment to function.
Enzymes in Food and Supplements
Cooking destroys enzymes found naturally in foods. However, eating foods raw or taking digestive enzyme supplements won't necessarily increase the amount of digestive enzymes available in your body. These enzymes are proteins, so they will be broken down by your stomach acid before they reach the small intestine, which is where these enzymes would be used.