Guaranteed Potency. 17% Oleuropein. Green Screened. Easy-to-Swallow Capsules. Solaray® Guaranteed Potency Herbs deliver confidence by providing exacting and consistent dosing of thoroughly tested herbs of the highest quality available. For the last 4000 years people in Mediterranean countries have used olive leaves as a supplement to their diets. Solaray® Olive Leaf extract is guaranteed to contain a minimum of 17% of the active compound oleuropein.