If you are a bodybuilder, one of your nutritional goals is undoubtedly to take in protein, break it down efficiently and absorb it into the bloodstream so that you can use the building blocks to make muscle. While you may have heard that papaya enzyme will help you do this, it's not only unnecessary, it's ineffective.
The process of building muscle depends upon repeated stress, which triggers an increase in muscle fiber size and number. The stress, which comes from lifting weights, signals processes in the muscle cells that cause them to increase protein synthesis, or building of proteins necessary for formation of muscle fibers. To build proteins, you need protein building blocks, called amino acids, which you obtain from protein in the diet, according to a report from the University of Arizona Biology Project.
When you consume protein, your digestive enzymes break it down into its constituent amino acids. Your small intestine then absorbs these into the bloodstream. The cells take up the amino acids from there, and depending upon cellular needs, use them in one of several ways. You can burn amino acids for energy or convert certain of them into sugar or fat. Alternately, you can use them to make molecules like hormones, or you can make cellular proteins with them.
Papaya enzyme is a proteolytic, meaning that it digests protein as explained by New York University Langone Medical Center. At first glance, it seems that taking papaya enzyme would help you break down the protein in your food so you could take it up more efficiently. There are a few problems with this theory, however. First, you don't actually need help breaking down protein -- digestive enzymes are very efficient, and deficiencies are exceedingly rare. Additionally, papaya enzyme can digest protein but can't affect absorption at all; that's up to the cells of the small intestine.
Another problem with the idea of taking papaya enzyme to help you absorb protein is that when you take the enzyme you subject it to the very acidic interior of the stomach. Strong acid denatures papaya enzyme, meaning it renders the enzyme completely inactive. After you inactivate the enzyme, your stomach digests it, meaning you break it down in into its component amino acids and absorb it for nutrition like any other protein -- you can't actually benefit from it as a proteolytic. Consuming proteolytic enzymes, such as papaya, may cause stomach upset and allergic reactions, according to NYU Langone Medical Center.