لخّصلي

Complementary and alternative therapies (CATs) are becoming increasingly popular globally, especially in the West where conventional medicine may not be effective for chronic conditions. Olive tree leaves, traditionally used in Europe and the Mediterranean, are rich in potentially bioactive compounds with antioxidant, antihypertensive, and other beneficial properties. While research on CATs is increasing, there is limited evidence on the effectiveness of olive tree leaves specifically for metabolic disorders, despite their use as folk remedies for diabetes.

Olive leaf extract, rich in oleuropein and other phenolic compounds, has shown promising results in animal studies. Oleuropein has been associated with improved glucose metabolism and antihyperglycemic effects in diabetic rodents. Studies have shown that olive leaf extract can reduce glucose, lipids, and other metabolic markers in diabetic rats, potentially making it a viable antidiabetic agent. Further research suggests that olive leaf extract may also positively impact cardiovascular and hepatic health in animals with a high-carbohydrate, high-fat diet.

Despite promising results, the mechanism by which olive leaf extract improves glucose metabolism remains unclear. This study aims to investigate the effect of olive leaf extract on glucose metabolism in human subjects with diabetes and explore the underlying mechanism in animal models.

long used in Eastern cultures, complementary
and alternative therapies are increasingly employed
throughout the world.1
In the west, individuals may seek out
‘‘unconventional’’ therapies such as herbal medicine when
conventional medicine fails to cure chronic diseases and
conditions.2–4 Olive tree (Olea europaea L.) leaves have
been widely used in traditional remedies in European and
Mediterranean countries. They have been used in the human
diet as extracts, herbal teas, and powder and contain several
potentially bioactive compounds that may have antioxidant,
antihypertensive, antiatherogenic, anti-inflammatory, hypoglycemic, and hypocholesterolemic properties.

The number of randomized trials on complementary
therapies has doubled every five years, and the Cochrane
library includes 100 systematic reviews of unconventional
interventions2–4; however, none of these studies specifically
addresses the efficacy of olive tree leaves and its extract
materials in metabolic disorders.1,6 Olive leaf tea and
chewing olive leaves are folk remedies for the treatment of
diabetes. The bioactivity of olive tree byproduct extracts
appears to be attributable to antioxidant and phenolic
components such as oleuropein, hydroxytyrosol, oleuropein
aglycone, and tyrosol.7
Studies indicate that biologically active compounds in
olive leaf products are effective in treating disorders.8,9
Several studies have shown that oleuropein (up to 6%–9% of
dry matter in the leaves), for example, possesses a wide
range of pharmacologic and health-promoting properties.10
Specifically, oleuropein has been associated with improved
glucose metabolism. Oleuropein has been reported to have an antihyperglycemic effect in diabetic rats.11,12 The hypoglycemic and antioxidant effects of oleuropein have been
reported in alloxan-diabetic rabbits.13 In streptozotocin
(STZ)-induced diabetic rats, olive leaf extract decreases
serum concentrations of glucose, lipids, uric acid, creatinine, and liver enzymes,14 implying that olive leaf extract is
more effective than glibenclamide and may be of use as an
antidiabetic agent. Rats fed a high-carbohydrate, high-fat
diet with olive leaf extract for 16 weeks expressed improved
or normalized cardiovascular, hepatic, and metabolic signs
than rats fed an identical diet without olive leaf extract. A
treatment benefit on blood pressure was not observed.15
The mechanism through which olive leaf extract attenuates
hyperglycemia is still not well recognized.13 In the present
study, we tested the effect of olive leaf extract on glucose
metabolism in human subjects with diabetes. Additionally,
we explore the mechanism in a series of animal models.