Olive leaf … not all extracts are created equal

Olive leaf extract is widely used by the public in the prevention and treatment of infections, and whilst there is some evidence in support of this usage, an unanswered question is how do different extracts compare in their phytochemical profile.

Five practitioner-only and four over-the-counter (OTC) Australian, and three OTC North American olive leaf extracts, were analysed in a specialist olive chemistry laboratory using high performance liquid chromatography and gas chromatography. Key compounds quantified included oleuropein, hydroxytyrosol, oleacein, luteolin, maslinic acid, oleanolic acid, erythrodiol and uvaol.

Practitioner and over-the-counter olive leaf extracts on the Australian and North American marketplace demonstrated considerable variation in phytochemical profiles, with a more than four-fold difference in oleuropein concentration between practitioner extracts being observed. In contrast, oleuropein concentrations in sampled OTC products were generally more consistent, and correlated well with label claims. Significant quantitative differences in other constituents were also observed.

This research demonstrates considerable variability between olive leaf extracts, raising the question as to whether clinical results from different olive leaf extracts will be consistent, comparable, or reliable.