Olive Oil and Olive Leaf — A Mediterranean Secret to a Healthy Heart?

Aim of the study: The Mediterranean diet is often associated with longevity and a lower incidence of adverse cardiovascular events because of the biological activity and health effects of olives, its key component. Olive oil, olive leaf extract, fruits, and various by-products contain many bioactive components with antioxidant, anti-inflammatory, and anti-apoptotic effects.

Results: Olive oil, olive leaf extract, fruits, and various by-products contain many bioactive components with antioxidant, anti-inflammatory, and anti-apoptotic effects. This review focuses on recent studies examining the molecular mechanisms behind the heart-protective properties of different olive oils, olive leaf extracts, and specific minor components (such as oleuropein, tyrosol, hydroxytyrosol, and others) in laboratory studies, rodent models, and clinical trials involving people. In particular, hydroxytyrosol and oleuropein were identified as the main bioactive compounds responsible for the antioxidant, anti-inflammatory, anti-platelet aggregation, and anti-atherogenic effects of olive oil. Overall, the results discussed showed a positive association between olive oil consumption and improved outcomes in atherosclerosis, diabetes, myocardial infarction, heart failure, hypertension, and obesity.

Aim of the study: Alzheimer's disease (AD) is the most common form of dementia among several neurodegenerative disorders affecting older people. AD is characterized by the buildup of extracellular amyloid-β (Aβ) plaques, a disrupted blood-brain barrier (BBB), and neuroinflammation.

Results: Mice were fed an OLE-enriched diet (695 μg/kg body weight/day) for 3 months, starting at 3 months of age. Overall, the findings showed that OLE reduced neuroinflammation by inhibiting the NF-κB pathway and suppressing the activation of NLRP3 inflammasomes and the RAGE/HMGB1 pathways. In addition, OLE reduced total Aβ levels in the brain by increasing its clearance and reducing its production. It also improved the integrity and function of the BBB. Together, these effects improved memory. Thus, taking OLE as a dietary supplement is expected to stop and/or slow the progression of AD.

Aim of the study: Natural products have recently received considerable attention as complementary or alternative agents for treating anemia. In this regard, olive leaf extract, which is rich in bioactive phenolic compounds, has been reported to induce red blood cell development in human hematopoietic stem cells.

Results: After 8 weeks of taking WOL, red blood cell counts and hemoglobin levels increased significantly. Notably, there were no significant changes in safety measures related to liver and kidney function. We also identified oleuropein and oleuroside as the active components in WOL that induce red blood cell development in the K562 cell line. Overall, our study provides evidence of WOL's potential to support blood formation in living organisms, opening up promising possibilities for future use in preventing or treating anemia.

Aim of the study: Olive oil and olive leaf extract have several health benefits; however, their protective effects against fluoxetine-induced liver injury have not been investigated. This study aimed to examine the impact of fluoxetine on rat livers and evaluate the protective effects of olive oil and olive leaf extract.

Results: Taking olive oil and olive leaf extract together significantly reduced circulating liver-function marker enzymes and pro-inflammatory cytokines, and prevented fluoxetine-induced changes in tissue structure. Both olive oil and leaf extract significantly reduced lipid peroxidation and nitric oxide in the liver, and improved levels of glutathione, superoxide dismutase, catalase, and glutathione peroxidase. In addition, olive oil and leaf extract prevented fluoxetine-induced apoptosis in rat livers, as shown by reduced expression of Bax and caspase-3 and increased expression of Bcl-2. In conclusion, olive oil and leaf extract protect against fluoxetine-induced liver injury in rats by reducing oxidative stress, inflammation, and apoptosis.

Aim of the study: Olive oil, commonly used in the Mediterranean diet, is known for health benefits related to a reduced risk of cancer, coronary heart disease, hypertension, and neurodegenerative disease. These unique properties are attributed to the phytochemicals in olive oil, which have strong antioxidant effects.

Results: Despite the positive results, the beneficial health effects of olive derivatives have not been confirmed in people. In conclusion, olive derivatives, especially olive oil and leaf extract, may stimulate thyroid function. Olive pomace residue is not suitable for pharmaceutical or dietary supplement use. The therapeutic use of olive oil and leaf extract, especially in people with hypothyroidism, requires further confirmation through studies in humans.

Aim of the study: Neurological diseases such as stroke and multiple sclerosis are associated with high rates of illness and death, long-term disability, and social and economic costs. They therefore pose a major challenge for medical treatment.

Results: Polyphenols from olive oil, especially extra virgin olive oil, olive leaves, olive leaf extract, and other olive tree derivatives, reduce inflammation and oxidative stress, two major factors in demyelination. They also reduce the risk of stroke through several effects, including anti-atherosclerotic, blood-pressure-lowering, antioxidant, anti-inflammatory, cholesterol-lowering, blood-glucose-lowering, and anti-thrombotic effects. Olive polyphenols also benefit blood lipid profiles and insulin sensitivity in people with obesity. This review provides an updated account of the beneficial properties and mechanisms of action of olive polyphenols against demyelination, in the prevention or mitigation of multiple sclerosis—the most common non-traumatic neurological cause of disability in younger adults—and against brain injury, which is becoming more common and has already reached epidemic proportions.

Aim of the study: Although synthetic preservatives and antioxidants may have strong antimicrobial and antioxidant effects, they are usually associated with adverse effects on human health. There is currently growing interest in natural antimicrobial and antioxidant agents. This study aimed to evaluate the antimicrobial activity of two medicinal plant extracts and one active compound.

Results: Oleuropein showed complete antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. In this context, a 7-log reduction was achieved during the storage period (4 weeks). Oleuropein showed no antifungal activity at low concentrations (0.2%), but reduced Aspergillus niger by 2.35 logs at higher concentrations (0.6% w/v). Similar antibacterial and antifungal properties were observed for olive leaf extracts. Oleuropein at a concentration of 0.4 w/v and a mixture of oleuropein and thyme at concentrations of 0.4 and 0.1 (v/v) showed strong antimicrobial activity against the microorganisms studied. Olive leaf extract, thyme oil, and oleuropein have strong antibacterial and weak antifungal properties. Oleuropein and thymol also showed good synergistic effects.

Aim of the study: (1) Background: The health-promoting properties of extra virgin olive oil (EVOO), including its antioxidant and anti-inflammatory effects, are now well recognized and are mainly attributed to its various polyphenols, such as oleocanthal and oleacein. In EVOO production, olive leaves are a valuable by-product. They show a broad range of beneficial effects because they contain polyphenols, especially oleuropein.

Results: For further biological testing, an EVOO extract enriched with 8% OLE was selected. Its antioxidant effects were evaluated using three different methods (DPPH, ABTS, and FRAP), and its anti-inflammatory properties were assessed by measuring the inhibition of cyclooxygenase activity. (3) Results: The antioxidant and anti-inflammatory profiles of the new EVOO/OLE extract were significantly improved compared with those of the EVOO extract. (4) Conclusions: Combining OLE and EVOO extract can produce an extract enriched in bioactive polyphenols with better biological properties than EVOO extract alone. It may therefore be a new supplement in the nutraceutical field.

Aim of the study: The traditional Mediterranean diet (MD) is associated with a long life and a lower prevalence of cardiovascular disease and cancer. Its main components include a high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO), and fish, and a low intake of dairy products and red meat.

Results: The pathways and signaling cascades affected include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as phytoestrogens. Because olive polyphenols have a structure similar to that of estrogens, researchers have suggested that they may interact with estrogen receptors, thereby reducing the prevalence and progression of hormone-related cancers. Evidence for the protective effects of olive polyphenols against cancer in humans remains anecdotal, and clinical trials are needed to support these claims. This review aims to bring together the current literature on the bioavailability and mechanisms involved in the potential anticancer effects of olive leaf polyphenols.