An enzyme-and-carotenoid double act, with ripe and green versions that are nutritionally quite different.
Papaya shares pineapple's enzyme-driven research angle — its own protein-digesting enzyme, papain, alongside a genuinely high vitamin C content and carotenoids that give ripe papaya its orange-pink colour.
Papain has a long history of use as a natural meat tenderiser and is studied for digestive and anti-inflammatory applications, similar in principle to bromelain. Ripe papaya is also a strong source of lycopene (the same carotenoid covered in our tomatoes profile) and beta-carotene, both studied for antioxidant activity.
Unripe green papaya, used in some Southeast Asian cuisines, contains higher concentrations of active papain than ripe papaya, but far less lycopene and beta-carotene, which develop as the fruit ripens — the two forms are genuinely different foods nutritionally, not just a ripeness preference.
Ripe papaya needs no preparation beyond removing the seeds and skin — eaten plain, blended into a smoothie, or added to a fruit salad.
One of the more vitamin C-dense common fruits available — a single papaya can provide well over a day's typical intake.