Benefits
Cardiovascular support
In a controlled trial a related olive leaf extract did not significantly change blood pressure or blood lipids. The clearest human evidence for olive polyphenols is that olive oil polyphenols raise HDL cholesterol and lower oxidized LDL. No trial of SelectSIEVE Olive itself has been published.
Antioxidant defense
Hydroxytyrosol and oleuropein are powerful antioxidants that protect cells and LDL cholesterol from oxidation.
Blood sugar and lipids: no measured benefit
In the cited human trial olive polyphenols did not significantly change blood sugar, insulin or blood lipids. Any metabolic benefit is unproven.
Mechanism of action
Olive polyphenol action
Oleuropein and hydroxytyrosol support nitric-oxide-mediated blood-vessel relaxation and antioxidant defense.
Anti-inflammatory action
Olive polyphenols calm oxidative and inflammatory stress in blood vessels and tissues.
Clinical trials
Randomized, double-blind, placebo-controlled trial of a different branded olive LEAF extract (500 mg/day for 8 weeks) in 77 overweight adults with mildly elevated cholesterol. It found no significant effect on any cardiovascular marker. This is not a trial of SelectSIEVE Olive. (Stevens et al. 2021, European Journal of Nutrition)
Adults.
In this trial the olive leaf extract did not significantly change blood lipids, oxidized LDL, blood pressure, glucose, insulin or liver markers compared with placebo over 8 weeks.