Extract standardized to oleuropein.
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Olive leaf is one of the oldest medicinal resources of the Mediterranean: the Egyptians used it in mummification, the Greeks and Romans as an antiseptic and fever reducer, and traditional Mediterranean medicine has maintained its use for millennia for fever, blood pressure, and the "heat" of the blood; modern research has confirmed that behind this long tradition are potent polyphenolic compounds (especially oleuropein and hydroxytyrosol) with cardiovascular and antioxidant effects documented in serious clinical trials.
Unlike extra virgin olive oil (whose cardiovascular benefits are widely recognized and come mostly from its monounsaturated fatty acid profile), leaf extract contains much higher concentrations of active polyphenols without the calories of the oil, which makes it a concentrated way to obtain some of the cardiovascular benefits of the "polyphenolic Mediterranean diet" in supplement form.
Several randomized trials have shown that doses of 500-1,000 milligrams per day of extract standardized to 16-20 percent oleuropein for 6-8 weeks reduce systolic blood pressure by 5 to 11 mmHg and diastolic by 3 to 5 mmHg in people with mild hypertension, an effect comparable to that of some mild pharmacological antihypertensives as monotherapy and to that of the hibiscus we mentioned in another article.
A comparative randomized trial published in Phytomedicine in 2011 pitted olive leaf extract (500 mg twice a day) against captopril (12.5-25 mg twice a day) for 8 weeks in people with mild to moderate hypertension: both treatments showed similar efficacy in lowering blood pressure, an equivalence with a standard ACE inhibitor drug that is notable and suggests real pharmacological effects not attributable to placebo alone.
On the lipid profile, several studies have shown modest reductions in total cholesterol and LDL with prolonged use, especially in people with mild dyslipidemia; on blood glucose, data in people with type 2 diabetes suggest small improvements in HbA1c and insulin resistance; on immune function, the extract has modest antiviral and antibacterial activity documented in vitro, with preliminary clinical data in viral respiratory infections that are not yet consolidated.
As a concentrate of polyphenols, olive leaf has a very high antioxidant capacity as measured by standardized assays, with systemic anti-inflammatory effects documented in prolonged use; hydroxytyrosol, one of the most potent polyphenols in the extract, is approved by the EFSA with a specific cardiovascular health claim (5 mg per day protects blood lipids from oxidative stress).
The doses studied range from 500 to 1,000 milligrams per day of extract standardized to 16-20 percent oleuropein, divided into one or two doses with or without food; the effects on blood pressure appear between 4 and 8 weeks and are maintained for as long as treatment lasts; infusions of dried whole leaf have much lower polyphenol concentrations and a less predictable clinical efficacy.
Generally well tolerated; adverse effects are rare and mild (digestive discomfort, occasionally headache); people taking antihypertensives should monitor their response to avoid hypotension from an additive effect, and those taking antidiabetic drugs may need a dose adjustment if the effect on blood glucose is notable; people with a known allergy to olive or its pollens should avoid it, and caution is advisable in pregnancy and breastfeeding because of limited data on reproductive safety.
Information, not medical advice. Scientific evidence reflects the quality of the studies.