Papaya Leaf (Carica papaya)
The primary use of papaya leaf in herbal medicine today is as a vermifuge, that is, to remove intestinal worms. Papaya leaf has less of the protein-dissolving papain than the fruit, so it is less likely to "dissolve" the worms, but it contains tannins that the fruit does not. These tannins protect the intestine from reinfection by "tanning" proteins in the lining of the intestinal wall so that worms cannot attach themselves.
The leaf contains beta-carotene, calcium, carpaine, fats, flavonols, niacin, papain, tannins, and vitamin C (in higher concentration in the leaf than in the fruit). The leaf, unlike the fruit, is not a source of the protein-dissolving enzyme papain, but the latex (sap) in the leaf stem is. Papain remains in leaf preparations that have been dried over low heat, but it may be destroyed in products that are dried at high heat.
Infusions or teas, taken in small doses.
Physicians of nineteenth century America used papaya leaf to treat "fermentative indigestion," a condition of bloating, nausea, and flatulence frequently following excessive consumption of fermented foods.