The papaya (also called papaw, pawpaw, mamao, or tree melon) is believed to have originated in southern Mexico, Central America, or the West Indies, but is now grown in tropical and subtropical areas around the world. It is a pear-shaped fruit with skin that turns from green to a bright orange-yellow as it ripens. It is also the source of 1 of nature’s own digestive aids: papain.
What is Papain?
Papain is a milky latex that is collected by making incisions in unripe papayas. It is one of a group of proteolytic enzymes found in papayas, pineapples, and certain other plants. Proteolytic enzymes help you digest the proteins in food.
Where Does Papain Come From?
Papain comes from the papaya, a tropical fruit that is about 6 inches long and can range from 1-20 pounds in weight, depending on the variety. Inside, the papaya has silky smooth, orange-yellow flesh and a large center cavity full of shiny grayish-black seeds. The flesh is juicy and has a subtle, sweet-tart or musky taste, somewhat like a cantaloupe.
Papaya is now widely cultivated in tropical and subtropical countries. There are about 45 species of papaya. The most common variety in the United States is the Solo papaya, which is grown in Hawaii and Florida. Mexican papayas are much larger than the Hawaiian types and may be more than 15 inches long.
To extract papain latex from a papaya, the skin of an unripe papaya is cut. After the latex is collected, it is dried either by the sun or in ovens and sold in powdered form.
Pineapple stems are also a rich plant source of proteolytic enzymes.
What is Papain Used for?
The primary use of papain is as a meat tenderizer. It has also been used as a digestive aid for people who have trouble digesting proteins. However, a small double-blind, placebo-controlled trial found no benefit from proteolytic enzymes as a treatment for dyspepsia (indigestion).
There is weak evidence to suggests that papain, taken in combination with other enzymes, might improve the rate of recovery from various types of injuries and reduce the chronic pain and discomfort of conditions, such as neck pain and osteoarthritis. However, the studies that found these benefits all had significant problems, so the results aren't reliable. Proteolytic enzymes have also received mixed results as an aid to recover from surgery and as a treatment for shingles.
Many practitioners of alternative medicine believe that papain may be helpful for food allergies and autoimmune diseases. However, there is little to no meaningful evidence as yet supporting that papain actually works for these conditions.
Some Precautions to Consider
In clinical studies, papain and other proteolytic enzymes are believed to be quite safe, though they may occasionally cause digestive upset and allergic reactions.
If you are taking warfarin, aspirin, or other drugs that thin the blood, you should not take proteolytic enzymes without first discussing it with your doctor.
Family Doctor—American Academy of Family Physicians
National Center for Complementary and Alternative Medicine
Canadian Interdisciplinary Network for Complementary and Alternative Medicine Research
Homeopathic Medical Council of Canada
Papaya. University of Florida Extension website. Available at: http://sarasota.ifas.ufl.edu/FCS/FlaFoodFare/Papaya.pdf. Accessed March 29, 2016.
Papaya: general crop information. Knowledge master. University of Hawaii website. Available at: http://www.extento.hawaii.edu/kbase/crop/crops/I_papa.htm. Accessed March 29, 2016.
Proteolytic enzymes. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/biomedical-libraries/natural-alternative-treatments. Updated August 2013. Accessed March 29, 2016.
Last reviewed March 2016 by Michael Woods, MD Last Updated: 5/8/2014