Papaya is a natural remedy for many ailments, including atherosclerosis, heart disease, and rheumatoid arthritis, and helps keep your digestive and immune systems healthy. Papaya also contains the flavonoid beta carotene, which studies have proven to help protect against lung and mouth cancers. Other flavonoids, namely lutein, zeaxanthin, and cryptoxanthins, have potent antioxidant properties against free radicals that can wear down your body and cause premature aging and degenerative diseases.