In a randomized, double-blind study published in Phytomedicine (2011 Feb 15; 18(4): 251-8) involved patients with stage 1 hypertension and tested the efficacy of treatment with olive leaf extract. Two groups of patients were treated with either Captopril or olive leaf extract. Captopril is in a group of drugs called ACE inhibitors. ACE stands for angiotensin converting enzyme. At the start of the study, the mean systolic (top number) blood pressure was 148.4 in the group receiving the drug and 149.3 in the group receiving the olive leaf extract. After eight weeks of treatment, the olive leaf extract performed comparably to the drug. The olive leaf extract decreased the systolic blood pressure by 11.5, the Captopril reduced the systolic blood pressure by 13.7. The diastolic (bottom number) blood pressure was reduced 4.8 by the olive leaf extract and 6.4 by the Captopril. The group receiving the olive leaf extract enjoyed an additional benefit, a significant reduction in triglyceride levels. According to the authors of the study, “Olive (Olea europaea) leaf extract, at the dosage regimen of 500mg twice daily, was similarly effective in lowering systolic and diastolic blood pressures in subjects with stage-1 hypertension as Captopril, given at its effective dose of 12.5-25mg twice daily.”