Olive leaf extract is derived from the leaves of olive trees. It is distinct from olive oil, which is harvested directly from the olive fruit. While olive oil is used primarily for cooking and as a food ingredient, olive leaf extract is processed into a concentrated form as a supplement.

Olive leaf extract’s main purported benefit is its effect on cardiovascular health and metabolic health. Some research has found that olive leaf extract reduced blood pressure in people with prehypertension and hypertension^[1] and in the general adult population.^[3] However, the quality of the research was quite low. More recent research found no effect on blood pressure or other markers of cardiometabolic health.^[2] Given the low quality and limited amount of research, olive leaf extract might be beneficial for cardiovascular health, but these findings should be interpreted with caution.

Clinical trials in humans have found olive leaf extract to be generally well tolerated.^[3] There are some reports of stomachache, headache, and acne after supplementation.^[4] However, more research is needed to fully understand any potential drawbacks of olive leaf extract supplementation.

Olive leaf extract works primarily through its polyphenols, such as oleuropein. These substances are believed to have numerous benefits, such as antioxidant, antihypertensive, antidiabetic, and anti-inflammatory effects.^[5][6] However, a majority of these benefits come from in vitro and animal studies.