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Olive Leaf Extract (Oleuropein)
Oleuropein-rich extract with blood pressure-lowering effects and narrow-spectrum antimicrobial activity — part of the Mediterranean diet's polyphenol profile.
What the evidence says
Olive Leaf Extract doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 1991–2026 with a typical study size of 62 participants.
Based on 76 studies · 4 meta-analyses · 44 RCTs · 3,918 total participants
Confidence
High confidenceBy outcome
Earns a Strong 7 from multiple RCTs and meta-analyses showing modest but reproducible blood-pressure lowering plus cardiometabolic and insulin-sensitivity benefits, tempered by mixed lipid results and some null trials.
12 trials ongoing or recruiting · 25 completed on ClinicalTrials.gov
Registered trials show research momentum for Olive Leaf Extract, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
Under EU law (Reg. 1924/2006), EFSA reviews whether a specific health claim for Olive Leaf Extract meets the evidence standard. These are independent regulatory decisions on claims — not studies, and never counted toward the evidence score above.
“Not authorised” means the specific claim wording did not meet the EU’s evidence standard — often a matter of dossier or phrasing, not proof of no effect. EFSA judges marketing claims and is kept separate from our study-based evidence score.
Source: EU Register of nutrition and health claims (European Commission / EFSA) · register snapshot Feb 2013
Olive Leaf Extract contains oleuropein and other polyphenols studied mainly for cardiovascular and antioxidant effects. Randomized trials show modest blood pressure reduction in hypertensive populations, though results are mixed.
Its antimicrobial activity is narrow rather than broad-spectrum (notably against H. pylori, C. jejuni, and S. aureus/MRSA in vitro). Used traditionally for infections and immune support, it reflects part of the Mediterranean diet's polyphenol intake.
Narrow-spectrum activity against select bacteria (e.g. H. pylori, S. aureus/MRSA) in vitro
Helps relax blood vessels
How Olive Leaf Extract works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Insufficient data; consult doctor
Olive leaf extract has blood-pressure-lowering (ACE-inhibiting) activity; additive effect with antihypertensives can cause hypotension. Monitor BP.
May affect blood sugar A grade for this interaction is held for clinical review and has not been validated, so no severity is given. The precaution still applies: ask a pharmacist about the exact supplement and medicine. Do not stop or change prescribed medicines based on this notice.
Tip: Take with food
Tip: Start with lower dose
Olive Leaf Extract has an evidence score of 7/10 — strong evidence based on 76 indexed studies, including 3 meta-analyses. Oleuropein-rich extract with blood pressure-lowering effects and narrow-spectrum antimicrobial activity — part of the Mediterranean diet's polyphenol profile. Representative study: PMID 39828996.
The commonly studied dose of Olive Leaf Extract is 500-1000mg (standardized to 15-20% oleuropein). Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Olive Leaf Extract is with meals. Taking it with food is preferred. Olive leaf extract contains oleuropein and hydroxytyrosol, polyphenols with cardiovascular and antimicrobial properties.
Olive Leaf Extract is generally well-tolerated and considered safe for most healthy adults at recommended doses. Reported side effects are uncommon and include GI upset, herxheimer reaction (die-off). Use caution if any of these apply to you: Known allergy or hypersensitivity to Olive Leaf Extract or related compounds; Pregnancy and breastfeeding; Low blood pressure (may lower BP further).
Aged Garlic Extract
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Andrographis
Likely helpsStudied for comfort and symptom duration during upper-respiratory infections when taken at onset — also supports liver health.
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Mixed evidenceWell-researched extract that prevents UTI-causing bacteria from adhering to the urinary tract — best for prevention, not treatment.
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Reviewed by Dr. Baher Al Hakim · Last reviewed May 2026 · evidence from 76 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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