Papaya Leaf (Carica papaya). On one of his many journeys to the West, Columbus, while observing the eating habits of the natives of the Caribbean, noticed that when they ate heavy meals of fish and meat, the meal was followed by papaya, and there was no apparent indigestion. In modern times, we have discovered that the unripe papaya contains, in its milky juice, a protein-digesting enzyme known as papain, which resembles the animal enzyme pepsin, in its digestive action. The unusual quality of papain, unlike other enzymes that can only digest protein in an acid or an alkaline medium, is that it acts in all three, neutral, alkaline or acid. Native Central American Indians also used the juice of the plant to remove warts, tumors and corns. Papaya is also known to have another important quality in that it helps to prevent ulcers and helps to heal them after they have developed. It has shown the ability to increase the blood’s coagulation properties and at the same time, reduce acid secretions, which could account for the beneficial action it has on stomach ulcers.