Olive LeafOlea europaea
What is Olive Leaf Extract Used for Today?
Olive leaf contains a substance called oleuropein, which breaks down in the body to another substance called enolinate. On websites that promote olive leaf extracts, it is stated that enolinate kills harmful bacteria, viruses, and fungi in the body, but at the same time nurtures microbes that are good for health. This remarkable claim, however, has no meaningful scientific justification.
However, it is a long way from test-tube studies to evidence of efficacy in humans. Only double-blind , placebo-controlled studies can prove a treatment effective, and the only study of this type reported for olive leaf was too flawed to prove anything. This small, poorly designed trial supposedly found that olive leaf extract reduces blood pressure . 12 However, the study was too small and too poorly designed to produce meaningful results. The only other support for the widespread claim that olive leaf reduces blood pressure comes from test-tube and animal studies that are too preliminary to rely upon at all. 13-16
Olive leaf has not undergone comprehensive safety testing. However, based on the limited evidence available, it does not appear to commonly cause much more in the way of immediate side effects than occasional digestive distress. Safety in young children, pregnant or nursing women, or people with severe liver or kidney disease has not been established.
8. Lee-Huang S, Zhang L, Huang PL, Chang YT, Huang PL. Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment. Biochem Biophys Res Commun . 2003;307:1029–37.
13. Fehri B, Aiache JM, Memmi A, Korbi S, Yacoubi MT, Mrad S, Lamaison JL. Hypotension, hypoglycemia and hypouricemia recorded after repeated administration of aqueous leaf extract of Olea europaea L. J Pharm Belg . 1994;49:101–8.
14. Khayyal MT, el-Ghazaly MA, Abdallah DM, Nassar NN, Okpanyi SN, Kreuter MH. Blood pressure lowering effect of an olive leaf extract ( Olea europaea ) in L-NAME induced hypertension in rats. Arzneimittelforschung . 2002;52:797–802.
15. Ribeiro Rde A, Fiuza de Melo MM, De Barros F, Gomes C, Trolin G. Acute antihypertensive effect in conscious rats produced by some medicinal plants used in the state of Sao Paulo. J Ethnopharmacol . 1986;15:261–9.
17. Fehri B, Aiache JM, Memmi A, et al. Hypotension, hypoglycemia and hypouricemia recorded after repeated administration of aqueous leaf extract of Olea europaea L [in French]. J Pharm Belg . 199449:101–8.
19. Onderoglu S, Sozer S, Erbil KM, Ortac R, Lermioglu F. The evaluation of long-term effects of cinnamon bark and olive leaf on toxicity induced by streptozotocin administration to rats. J Pharm Pharmacol . 1999;51:1305–12.
Last reviewed October 2007 by EBSCO CAM Review Board
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