Notes from Dr. Terry
Hydroxytyrosol is the major polyphenol component of olive leaf and its extracts, and is further hydrolyzed to form oleuropein, which is the common benchmark compound used for the standardization of olive leaf extracts in the market. The content of hydroxytyrosol in the St. Francis Herb Farm product is not assayed, though each capsule contains 18 mg of oleuropein, so the results of this study are relevant to our capsule product. (Note that our tincture is not assayed for either component, but both tincture and capsule are full-spectrum extracts that contain both constituents).
The study https://pure.roehampton.ac.uk/portal/files/245279/2015._Olive_leaf.pdf was a randomized placebo-controlled, clinical trial used to assess the effects of olive leaf extract on blood flow in 18 healthy individuals. Olive leaf extract (OLE) standardized to 51 mg of oleuropein (roughly 2.5 caps of St. Francis Herb Farm product) and 10 mg of hydroxytyrosol was used. (Hydroxytyrosol occurs naturally at a rate of from 0.82-4.12%, so we can assume a content of from 4-20mg per capsule for the St. Francis Herb Farm capsule product, and half as much per ml of tincture, i.e. from 2-10mg (each ml of tincture contains 250 mg of olive leaf).
The authors used an assessment of vascular function called “digital volume pulse” (DVP) to assess arterial stiffness, as well as inflammatory status by measuring an inflammatory marker in the blood known as Interleukin 8. Both measures can be used to predict future cardiovascular disease risk. Both indices were significantly improved in those individuals who took the OLE, as compared to placebo.
Olive leaf is best known for helping to maintain healthy blood pressure levels. This research confirms that there are indeed measurable benefits being derived from olive leaf use.
Read a summary of the research: Secoiridoids delivered as olive leaf extract induce acute improvements in human vascular function and reduction of an inflammatory cytokine
Dr. Terry Vandeheyden is a naturopathic doctor, registered herbalist and St. Francis Herb Farm medical advisor.