Papain

The four enzymes below are found in nature where they naturally break down proteins and starches. They perform the same function in the human body, where they complement the acids naturally found in the stomach to more rapidly break food down into its components for digestion.
Papain is a digestive enzyme found in papayas, as well as digestive tracts. Historically, it has been used for thousands of years to tenderize meat in South America. The reason for this, and its use as a digestive enzyme is because of its function breaking down tough protein fibers.