Metabolic and inflammatory effects of oleuropein and olive leaf extract: a systematic review and meta-analysis
Clinical Snapshot
PICO Framework
| P — Population | Adults participating in randomized controlled trials |
| I — Intervention | Olive leaf extract (OLE) or oleuropein supplementation |
| C — Comparator | Placebo or control |
| O — Outcomes | Glucose metabolism, lipid profile, and inflammatory markers |
Bottom Line
This well-conducted systematic review and meta-analysis of 11 RCTs found no convincing evidence that olive leaf extract or oleuropein supplementation provides clinically meaningful benefits for glucose metabolism, lipid profiles, or inflammation in adults. While the review followed rigorous methodology including PROSPERO registration and GRADE assessment, the heterogeneity of included studies and limited evidence base, particularly for inflammatory outcomes, undermines confidence in potential benefits. The authors appropriately conclude that current evidence does not support clinical recommendations for OLE supplementation. Clinicians should be aware that despite marketing claims, high-quality evidence does not support routine recommendation of olive leaf extract for metabolic health benefits. Patients interested in such supplements should be counselled about the lack of proven efficacy while considering potential opportunity costs of unproven interventions.
Key Findings
P Value: Not statistically significant
Effect Size: Not specified in abstract
Primary Outcome: No statistically or clinically significant effects on glycemic or lipid outcomes
Nnt Or Sensitivity: Not applicable - no significant benefit demonstrated
Confidence Interval: Not provided in abstract
Clinical Application
OLE supplements are readily available but evidence does not support routine clinical use Not listed on PBS; TGA regulates as complementary medicine; RACGP guidelines would not support routine recommendation based on this evidence General adult population considering olive leaf extract supplementation
Abstract
Background: Olive leaves, a by-product of olive oil production, are rich in oleuropein, a phenolic compound with antioxidant and anti-inflammatory properties. This systematic review and meta-analysis evaluated the effects of olive leaf extract (OLE) and oleuropein on glucose metabolism, lipid profile, and inflammatory markers in randomized clinical trials (RCTs). Methods: The review was registered in PROSPERO (CRD42022375615) and followed PRISMA guidelines. PubMed, Scopus, and Web of Science were searched up to January 2026 without restrictions. Eligible studies were RCTs in adults comparing OLE or oleuropein with placebo or control. Study selection, data extraction, and risk of bias (RoB 2) assessment were performed independently by two reviewers; certainty of evidence was assessed with GRADE. Meta-analyses were conducted when at least two trials reported suitable data. Results: Eleven RCTs were included (4 short-term and 7 continuous-intake trials). Short-term crossover studies showed heterogeneous effects on postprandial glycemia and insulin responses, precluding meta-analysis. In continuous-intake, parallel-design RCTs, pooled analyses demonstrated no statistically or clinically significant effects on glycemic or lipid outcomes. Evidence regarding inflammatory markers was scarce and of low certainty. Conclusion: The current evidence does not support clinical recommendations for OLE supplementation aimed at health benefits. Data from methodologically consistent and robust trials indicate no statistically significant metabolic or inflammatory effects under usual human consumption patterns, whereas evidence from other study designs remains inconclusive. Further high-quality RCTs are required to clarify potential metabolic benefits.
References
- 1.Menezes, R. C., Peres, K. K., da Mata, I. R., Dal Bosco, S. M., Garavaglia, J., & Dallegrave, E. (2026). Metabolic and inflammatory effects of oleuropein and olive leaf extract: a systematic review and meta-analysis. Food & Function. https://doi.org/10.1039/d5fo04235f
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