Olive leaf extract is sourced from olive plants and is believed to benefit glucose metabolism, prevent LDL oxidation, lower cholesterol and treat certain skin conditions.
The main bioactive present in olive leaf extract is oleuropein. This phenolic compound is thought to contribute to the anti-inflammatory and antioxidant properties of olive leaf extract.
Other components include tyrosol, hydroxytyrosol and dihydroxytyrosol. Together, they provide this extract with a growing list of health benefits.
Several in vitro studies have found that the extract can kill a number of microorganisms including yeasts, bacteria and fungi.
Preliminary research also shows its potential anticancer effects (1).
Olive leaf extract is rich in antioxidants. The phenolic compounds derived from olive leaves and oil (namely oleuropein), are known to possess several biological properties, many of which may be attributed to their antioxidant and free radical-scavenging activities.
Olive leaf extract benefits cardiovascular health. The phenolic content of olive oil has been shown to reduce lipid levels and reverse lipid oxidative damage — two factors that reduce one’s risk for developing coronary artery disease.
In a crossover study, participants were randomly assigned to receive three olive oils with low, medium and high levels of phenolic content. In addition to improving lipid levels and oxidative damage, all three olive oils increased high-density lipoprotein (HDL) cholesterol (a.k.a. “good cholesterol) and decreased triglyceride levels (2).
In another study, it was noted that the degree of LDL oxidation was lower as the phenolic content of the olive oil administered increased (3).
The oxidation of LDL is a complex process during which both the protein and the lipids undergo oxidative changes; Oxidized LDL cholesterol is considered to be a key factor in initiating and accelerating atherosclerosis (4).
The results of these two studies are promising considering that lipid peroxidation and oxidized LDL are hallmarks in the development of not only cardiovascular and metabolic diseases, but Alzheimer’s, rheumatoid arthritis and other diseases (5).
Olive leaf extract reduces high blood pressure. In a 2011 study, 500 mg of olive leaf extract was given twice a day for eight weeks. At the end of the study, a significant reduction of systolic blood pressure as well as diastolic blood pressure from baseline was noted.
There was also a significant reduction of triglyceride levels. This comparison study showed that olive leaf extract was similarly effective in lowering blood pressure as Captopril, a common drug prescribed to treat high blood pressure (6).
Olive leaf extract may reduce blood glucose. In a recent New Zealand study, 46 overweight, middle-aged participants were randomized to receive capsules with olive leaf extract or placebo for 12 weeks.
The results show that supplementation was associated with a 15 percent improvement in insulin sensitivity compared to placebo. There was also a 28 percent improvement in pancreatic β-cell responsiveness. The main role of pancreatic β-cells is to control glucose homeostasis (the balance of insulin and glucagon to maintain blood glucose). 7,8
Olive leaf extract has antimicrobial activity. The results of an in vitro study published in Mycoses, showed the antimicrobial potential of olive leaves against bacteria and fungi. The microorganisms tested were inoculated in various concentrations of olive leaf water extract.
Olive leaf water extract killed almost all bacteria tested, within 3 hours (9).
Some of the strains included in the study were dermatophytes (fungal infections of the skin), Candida albicans (fungal infection caused by yeasts) and Escherichia coli (E.coli) 10.
Another study identified seven phenolic compounds in olive leaves that showed potential in fighting human intestinal and respiratory tract infections (11).
Olive leaf extract may help treat a range of skin conditions. Skincare products containing olive oil have long been marketed for their hydrating properties. Research shows that olive leaves and oils go beyond alleviating dry skin.
Aqueous extracts of dried olive leaves were recently evaluated for their wound healing activity by using in vivo wound models.
The group of animals treated with the aqueous extract demonstrated increased contraction and a significant increase in wound tensile strength compared to the other groups (12).
According to the results of a study published in the International Journal of Cosmetic Science, oleuropein derived from olive leaves and oil helps improve UV-damaged skin. Results clearly showed that oleuropein formulations reduced redness, transepidermal water loss and blood flow of about 22 percent, 35 percent and 30 percent respectively (13).
Olive leaf extract may help fight cancer. A human leukemia cell line was recently used to assess the cytotoxic effects of olive leaf extract. Oleuropein and luteolin (another compound present in olive leaf extract) showed a dose-dependent cytotoxic (ability to destroy cancer cells) effect.
While more research is needed to prove this benefit, these very early results show the possibility of olive leaf extract being a nutraceutical used in the prevention of human cancer (14).
In another in vitro study, olive leaf crude extracts were found to inhibit cell multiplication of human breast adenocarcinoma, human urinary bladder carcinoma and bovine brain capillary endothelial (15).
Studies performed so far have not resulted in significant side effects, with doses up to 1000 mg daily for 8 weeks.
There is the possibility of a severe respiratory allergy in those who are allergic to the pollen from olive trees.
Interactions may occur when taking blood pressure medicine; olive leaf extract may increase the blood pressure lowering effect.
Olive leaf extract may also cause blood sugar levels to drop too low.
The typical daily supplemental range is 500-1000 mg. Consuming olive oil through diet, rather than supplementation, may be efficacious in preventing LDL oxidation.
Olive leaf extract has been shown to treat a range of medical conditions due to its antioxidant and anti-inflammatory properties. One of its most potent phenolic compounds is oleuropein.
Mounting evidence shows its efficacy in lowering lipid levels and reversing lipid oxidative damage — two contributors of cardiovascular disease.
It may also reduce high blood pressure, blood glucose levels, promote wound healing and improve UV-damaged skin.
Its antimicrobial activity may be a future, natural way to treat several types of infections.
Early in vitro studies also show its ability to destroy certain cancer cells.
Studies so far have resulted in few side effects. Pollen from olive trees may cause a severe respiratory allergy.