Olive Leaf Extract

What is olive leaf extract?

Olive leaf extract is made from the leaves of the olive tree, Olea europaea. Its best-known compound is oleuropein, a bitter polyphenol, along with smaller amounts of hydroxytyrosol. Supplements are usually standardized to a percentage of oleuropein. Labels may list the ingredient as “olive leaf,” “olive leaf extract” or simply “oleuropein.”

What the research says

Blood pressure and cholesterol

In a randomized crossover trial of 60 men with mildly raised blood pressure, an extract providing 136 mg of oleuropein a day for six weeks lowered 24-hour systolic and diastolic pressure by about 3 mmHg and slightly reduced LDL cholesterol and triglycerides compared with a control drink (Lockyer et al., 2017). The study was half-funded by the extract’s manufacturer.

Blood sugar and insulin

In 46 middle-aged men with overweight, an extract supplying about 51 mg of oleuropein a day for 12 weeks improved insulin sensitivity by 15% compared with placebo, without changing blood pressure, cholesterol or body composition (de Bock et al., 2013). The manufacturer supplied the product. When researchers pooled 12 randomized trials in 2024, results across glucose, blood pressure and lipids were inconsistent, and one analysis of low-dose studies actually favored the control groups for fasting glucose (Álvares et al., 2024). The authors called for more consistent studies.

Brain and focus

Olive leaf extract is sometimes placed in brain formulas because of its antioxidant content or its possible effects on blood sugar. We found no controlled human trials testing it on memory, attention or mental clarity, so any cognitive benefit is speculative. Better blood pressure and blood sugar control are good for long-term brain health in general, but that is a reason to manage those numbers with your doctor, not evidence that olive leaf itself sharpens memory.

How it’s used in supplements

Olive leaf extract is sold alone for heart and immune support and appears in blood sugar, blood pressure and general wellness blends. The amounts used in trials were tied to a specific oleuropein content. Without a disclosed dose and standardization, there is no way to know whether a blend matches the research.

Olive leaf extract was well tolerated in the trials above. Because it may modestly lower blood pressure and affect insulin sensitivity, people taking blood pressure or diabetes medicines should check with their doctor so their numbers can be monitored. Safety in pregnancy and breastfeeding has not been established, so it is best avoided then.