Rich in hydroxytyrosol, oleuropein and other polyphenols with potent therapeutic properties such as: antioxidant (prevents oxidation or cell damage), gastroprotective (protects digestive system), neuroprotective (protects central nervous system), antimicrobial (inhibits microorganism growth), anticancer (reduces risk of cancer), anti-inflammatory (reduces risk of inflammation), antinociceptive (reduces pain stimuli). It also helps reducing high blood pressure and high blood sugar, bad cholesterol in arrhythmia and heart disease.

Check the following references for info:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4227229/

https://academicjournals.org/journal/AJMR/article-full-text-pdf/E09C2B158944

https://onlinelibrary.wiley.com/doi/abs/10.1002/ptr.5445

https://link.springer.com/article/10.1007/s00394-016-1188-y

https://www.ffhdj.com/index.php/ffhd/article/view/114/237

https://www.hindawi.com/journals/ecam/2014/971890/

https://www.sciencedirect.com/science/article/abs/pii/S0009279716300977

https://www.researchgate.net/profile/Zeynep_Tirmikcioglu/publication/281430178_Olive_Leaf_Extract_Improves_the_Atherogenic_Lipid_Profile_in_Rats_Fed_a_High_Cholesterol_Diet/links/5a5f0395458515c03ee17a8c/Olive-Leaf-Extract-Improves-the-Atherogenic-Lipid-Profile-in-Rats-Fed-a-High-Cholesterol-Diet.pdf

https://www.academia.edu/19297544/Food_supplementation_with_an_olive_Olea_europaea_L_leaf_extract_reduces_blood_pressure_in_borderline_hypertensive_monozygotic_twins

https://www.academia.edu/4070163/Olive_Olea_europaea_leaf_extract_effective_in_patients_with_stage_1_hypertension_Comparison_with_Captopril

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0057622