Olea europaea · herb
Evidence tier: limited
A broad spectrum antimicrobial and cardiovascular tonic. Particularly useful for recurrent infections and blood pressure support.
Oleuropein, the bitter phenolic that defines the leaf, and its breakdown product hydroxytyrosol are potent antioxidants in the test tube and appear to relax blood vessels and improve endothelial function, which is the leading explanation for the small drop in systolic pressure. ACE inhibition is proposed in laboratory work but has not been demonstrated to be the operating mechanism in people at the doses used. The antimicrobial and antiviral activity is real in a dish and unproven in a person.
Olive leaf has a real but small blood pressure signal and almost nothing else. The pooled evidence is a 2022 systematic review and meta analysis of 12 randomised controlled trials in 819 adults, using 500 mg to 5 g of olive leaf extract daily for six to 48 weeks. It found systolic blood pressure fell by 3.86 mmHg overall and by 4.81 mmHg in people who already had hypertension, while diastolic pressure did NOT move significantly overall (1.18 mmHg) and only reached significance in the hypertensive subgroup. Triglycerides fell by about 9.5 mg/dl. Fasting glucose, HbA1c, insulin resistance and inflammatory markers did not improve, and the authors rate the quality of evidence for those outcomes low to very low (PMC9585795). A larger and more recent multicentre randomised double blind trial in 621 people found a 24 hour systolic reduction of only about 1.5 mmHg against placebo, which is smaller still and points the same way the literature usually points once trials get bigger: the effect shrinks. Put plainly, this is a couple of millimetres of mercury, comparable to what magnesium does, meaningful across a population and barely perceptible to a person. The immune and antiviral claim is much weaker than the marketing suggests. The only relevant randomised trial is 32 high school athletes taking olive leaf extract for nine weeks, which found NO significant difference in how many got ill and a 28 percent reduction in days sick. Olive leaf is not included in evidence based respiratory guidance. The antiviral, antibacterial and antifungal properties that appear on every label are laboratory findings about oleuropein, not human outcomes. Everything else, including blood sugar, weight and general wellness, is insufficient.
500 mg to 5 g of olive leaf extract daily is the range actually tested across the trials, most commonly a standardised extract taken once or twice daily, with benefit measured over six weeks or more rather than days. Products usually standardise to oleuropein content, and the trials that reported a respiratory outcome used about 100 mg of oleuropein daily.
500 to 1000 mg standardised extract (15 to 20% oleuropein) daily.
Lowers blood pressure, caution with antihypertensives. May lower blood sugar.
Pregnancy: caution
Breastfeeding: caution
Active compounds: oleuropein, hydroxytyrosol, oleacein, verbascoside
Remedies using Olive Leaf · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.