General Description
The olive tree is an evergreen native to the Mediterranean region
and naturalized in many warm or tropical climates throughout the
world. Growing to heights of 25 feet or more, the tree has a gnarled
trunk with hard, yellow wood covered by greenish-gray bark. The
leaves have a leathery texture and are elliptical, oblong, or spear-shaped.
The top side of the leaf is dark green, while the underside is covered
with silvery scales. The round, oblong fruit and the oil pressed
from it are used as food. Extracts from the leaves are used for
medicinal purposes.
Health applications
History and traditional use
The olive tree has been cultivated for over 6,000 years, predating
the written history of Western civilization. In ancient Greek mythology,
the olive tree was said to be the creation of Athena, the goddess
of wisdom. In the Old Testament of the Bible, the olive tree is
called "the tree of life," and an olive leaf delivered to Noah by
a dove is the first sign of dry land after the great flood. Olive
oil was used in foods, ointments, and as a mechanical lubricant.
The leaves were chewed or brewed in teas for various medical applications.
In an 1828 medical journal, French physician Etiene Pallas reports
the use of a drink made from ground olive leaves as an effective
fever reducer.1 Chemical
composition
The primary active component in olive leaves is a bitter compound
called oleuropein, which the body converts into various active
constituents including elenolic acid, alglycone, and calcium elenolate.
Olive leaves also contain a variety of other flavonoids and phenolic
compounds that may exert biological activity.
Antimicrobial
properties
Olive leaf extract is most commonly used to aid the immune system
in fighting off infection. Studies indicate that compounds in
olive leaves exert antiviral, antibacterial, and antifungal activity,
2-6 and may enhance the activity of white
blood cells in vitro.7 The antimicrobial activity
of olive leaf extract in vivo has not been documented. Further
research is needed to determine the efficacy of olive leaf extract
for fighting infections in human subjects.
Cardiovascular
health
Preliminary research suggests that olive leaf extract may be useful
for promoting cardiovascular health. Laboratory studies indicate
olive leaf extract has antioxidant, antihypertensive, and vasodilator
effects.8-11 One small clinical study on 18
patients with high blood pressure found that three months of treatment
with olive leaf extract resulted in significant reduction of blood
pressure for all test subjects.12 Larger,
placebo-controlled trials are needed before the efficacy of olive
leaf extract for the treatment of hypertension in human patients
can be determined.
Diabetes
In folk medicine, olive leaves have often been used for treatment
of diabetes.13
Studies on laboratory animals indicate that a compound found in
olive leaves exhibits significant hypoglycemic activity.14
However, it has not been proven whether olive leaf extract has
the same effect on human subjects.
Dosage/toxicity
Olive leaf extract has no known toxicity, and doses of 1,600 mg
per day (divided into four 400 mg doses) have been administered
with no significant side effects.12 |
