Evidence Level
Olive Leaf Extract is a natural supplement derived from the leaves of the olive tree (*Olea europaea*), rich in polyphenols such as oleuropein. Research on its effects spans in vitro, animal, and human studies, with a growing body of clinical trial data. Early findings by Micol et al. (2005) demonstrated the antiviral activity of olive leaf polyphenols, while Barbaro et al. (2014) reviewed its antimicrobial, antiviral, and anti-inflammatory mechanisms, confirming its efficacy against bacteria, viruses, fungi, and parasites.
In humans, studies have focused on cardiovascular outcomes, including blood pressure reduction and lipid profile improvement. A systematic review by Razmpoosh et al. (2022) found that olive leaf extract significantly reduced triglycerides, systolic blood pressure, and improved lipid profiles in adults, particularly those with hypertension. Álvares et al. (2024) conducted a meta-analysis of 12 RCTs involving 703 adults, suggesting potential benefits for glucose metabolism, though effects on other cardiometabolic factors were inconsistent.
Recent trials have explored additional applications. Fladerer-Grollitsch et al. (2026) reported that an olive leaf extract-potassium supplement reduced morning systolic BP by 5.4 mmHg in a randomized trial of 70 participants over 12 weeks. However, Câmara Rocha Menezes et al. (2026) found no significant metabolic or inflammatory effects of olive leaf extract/oleuropein in adults after reviewing 11 RCTs.
Overall, while olive leaf extract shows promise for cardiovascular and metabolic health, further research is needed to confirm its broader therapeutic applications.