Many types of enzymes are available as supplements. Enzymes, including the types in supplements and foods, are the normal and necessary basis for human metabolism.
There are thousands of different enzymes at work in the human body and in all living things. More information: What are enzymes?
In the human body, there are 3,000 known enzymes but there are certainly many more, perhaps tens of thousands more, still unidentified. Most of our genes exist to code for the production of enzymes; most of the protein we eat goes toward building our enzymes.
An enzyme is a biocatalyst; that is, it triggers and speeds up chemical reactions within an organic substance. That substance might be something in an animal or a plant, alive or dead, in a food or in a consumer.
Usually a specific enzyme facilitates only one biochemical reaction, that takes place in only one kind of substance. Thus many, many different kinds of enzymes are needed to carry out human metabolism.
To achieve complex activities, different enzymes operate in sequence. Enzymes work at great speeds and are in great numbers in the body.
There are six general types of enzymes—covering all enzymes in all organic material--classified by the way the chemical reaction works. These are: oxidoreductases; transferases; hydrolases; lysases; isomerases; and ligases.
Two of these types are important in enzyme supplements:
Hydrolases include digestive and immune-supporting enzymes, such as proteases, amylases, and lipases.
More information: What are digestive enzymes?
Oxidoreductases include antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase. Antioxidant enzymes prevent damage from free radicals and enable the body to repair itself. (Free radicals are byproducts of inflammation, infection, toxins, and normal metabolism.)
Notice that many names of enzymes end in "ase." Most enzymes break apart, or digest, the substance they affect. (Other enzymes build up substances.) Many enzymes are named for the substance that they break apart, adapted with the ending "ase" to indicate the action. "Proteases" break apart or digest proteins; "lactase" breaks apart or digests the milk sugar lactose.
The following are the names of enzymes commonly found in oral enzyme supplements or foods.
Some high-quality brands of enzymes supplements are discussed in Best Digestive Enzymes.
Lysozyme (also antibiotic and antiviral)
Here are articles identifying the enzymes that digest various types of foods and meals:
Enzymestuff.com: Enzymes That Work On Specific Food Types Or Compounds
Houston Enzymes: Tips For Matching Enzymes and Foods