Olive leaf has been used for centuries as a health-promoting herb. Research has demonstrated Olive Leaf to possess antioxidant and pathogen-inhibiting properties. Natural Factors Olive Leaf is standardized to contain eleuropein, the powerful phytochemical responsible for reinforcing the bodys natural resistance to pathogens. All Natural Factors products are manufactured according to Canadian Health Protection Branch Good Manufacturing Practices (GMP), among the highest standards in the world.