A recent study of olive leaves from Spain and Greece found differences in phytochemical makeup.
Olive oil is known to have health benefits, but what about the olive leaf?
Greece vs. Spain
Researchers from Romania conducted a study, published in Antioxidants on June 27, to investigate olive leaves’ phytochemical composition and potential.
The researchers harvested olive leaves from Seville, Spain, and Lefkada, Greece, dried and ground them, and then mixed them with a solvent to prepare them for analysis.
The extracts were tested for toxicity to human melanoma cells and evaluated for their effect on blood vessel growth. When a tumor develops, more blood vessels typically begin to grow to supply the tumor with nutrients.
The olive leaf extracts from Greece contained more polyphenols, such as lutein, which improves eye health, and oleuropein, which has antioxidant, lipid-lowering, anti-atherosclerosis, and anti-inflammatory properties.
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Additionally, Spanish olive leaf extracts contained nearly double the metal content of extracts from Greece. Spanish olive leaf extracts had higher levels of nickel, zinc, copper, chromium, and iron—all necessary nutrients. However, they also contained higher levels of cadmium and aluminum, which can be toxic in high doses. The researchers did not determine the levels to be toxic.
Olive leaf extracts from Greece had greater antioxidant activity, making them more effective at combatting free radicals. They were also more effective at killing melanoma cells and better at preventing the formation of blood vessels, another anti-cancer property.
However, olive leaf extracts from Spain were more effective against a broader range of bacteria, indicating they contain more antimicrobial properties. Spanish extracts did not affect blood vessel formation.
“Our findings contribute to a wider characterization of olive leaves originating from Spain and Greece … with phytochemical and biological data indicating possible use as high antioxidant extracts with a potential impact on the healthcare system,” the research team wrote.
Why the Difference?
The researchers believe the difference in chemical makeup is likely due to the differences in climate and cultivation regions between Greece and Spain. As such, the research team said it is essential to consider the type of olive leaf when producing therapeutics.
“In plant determination, elemental content has been considered individually, thinking only of the contribution of the respective element to the plant and the human organism and compared to recommended daily intakes and daily permissible limits,” the researchers wrote.
Since olives are also grown in other parts of the world, including Portugal and Italy, it is important to test the efficacy of the compounds in olive leaves harvested from these countries as well, the team noted.
