Zero effect of multiple dosage of olive leaf supplements on urinary biomarkers of oxidative stress in healthy humans

ObjectiveWe determined the effect of dietary supplementation with an olive leaf capsule or liquid extract on oxidative status of young and healthy male and female subjects.MethodsThis was a single-center, randomized, single-blinded, prospective pilot comparison of the effect of dietary supplementation with olive leaf extracts. Healthy young adult male and female subjects (n = 45) were randomized into three groups and received daily doses of control, capsule, or liquid extract of olive leaf. Urinary F_2α-isoprostane, 8-hydroxy-2′-deoxyguanosine, and Folin-Ciocalteu total reducing power were measured to assess the impact of supplementation.ResultsBaseline values (mean ± standard deviation) of the biomarkers were 0.24 ± 0.13 μg, 9.16 ± 2.94 μg, and 424.9 ± 121.4 mg of gallic acid equivalents per gram of creatinine, respectively, for the control group. Using these markers, supplementation with liquid or capsule did not alter oxidative status compared with the control group. Possible reasons for the lack of an observed correlation are presented.ConclusionDietary supplementation with olive leaf extract did not alter the oxidative status of healthy young adults.