Papain is a protein digesting enzyme taken from unripe papaya fruit. Take it with meals to help break dietary protein down into peptides and amino acids.
Some people take papain between meals hoping to ease joint stiffness and speed recovery after exercise. Real proof that it works this way is thin.
You can buy papain standardized to FCC papain units. It comes as tablets, capsules, powders, or as a meat tenderizer. Papain can raise bleeding risk, especially if you take blood thinners or aspirin. Stop taking it before surgery. Anyone with a latex allergy should avoid it.