According to James Privitera, M.D., the olive leaf was mentioned in the Bible. Throughout history, its medicinal properties have been recognized and used, especially in Europe. The olive leaf has an antibacterial compound, which fights many illnesses caused by bacteria. According to True Parenting, the main ingredient in olive leaf is the phytochemical oleuropein. This element breaks down into elenolic acid, which is antibacterial and thus fights bacterial infection.