Benefits
Blood pressure in adults with mildly raised readings: preliminary, no placebo
In an 8-week open study in 40 twins with borderline high blood pressure, average readings fell from 137/80 to 126/76 mmHg on 1,000 mg per day but did not change on 500 mg or with lifestyle advice. In a second 8-week trial, systolic pressure fell about 11.5 mmHg from baseline on 500 mg twice daily, but there was no placebo group. These are preliminary, maker-linked results.
Blood pressure with a placebo control: unchanged in a three-extract blend
The only placebo-controlled trial containing Benolea was null. It gave 1,000 mg per day together with green coffee bean extract and beetroot powder for 6 weeks, in a crossover design, to 37 overweight adults with high-normal or mildly raised blood pressure. 24-hour and clinic blood pressure, arterial compliance, lipids, glucose and insulin did not differ from placebo.
Cholesterol and triglycerides: secondary findings, not placebo-confirmed
In the open twin study, cholesterol fell in all groups, with dose-dependent differences in LDL cholesterol within twin pairs. In the active-controlled trial, triglycerides fell on the extract but not in the comparison group. These are preliminary findings. In the main analysis of the placebo-controlled blend trial, and in a placebo trial of a different olive leaf extract, lipids did not differ from placebo.
Mechanism of action
Oleuropein activity
Oleuropein, the main polyphenol in olive leaf, and its breakdown product hydroxytyrosol are studied for effects on blood vessel tone and antioxidant defense, mostly in laboratory and animal work. These are proposed mechanisms; the Benolea human trials measured blood pressure and blood lipids, not these pathways.
Blood pressure in a nitric oxide blocking rat model
In rats given L-NAME, a compound that blocks nitric oxide production and raises blood pressure, oral EFLA 943 for 8 weeks limited the rise in blood pressure in a dose-dependent way, with the best effect at 100 mg/kg. This is animal evidence only and does not show the same effect in people.
Clinical trials
Open (unblinded) 8-week study of the olive leaf extract EFLA 943 (Benolea). The twins of each pair were placed in different groups: 500 mg per day, 1,000 mg per day, or advice on a favourable lifestyle. Weight, heart rate, blood pressure, glucose and lipids were measured every two weeks. The first author worked for Frutarom Switzerland, the maker. (Perrinjaquet-Moccetti et al. 2008, Phytotherapy Research)
40 identical (monozygotic) twins with borderline high blood pressure.
After 8 weeks, average blood pressure fell significantly on 1,000 mg per day (137/80 to 126/76 mmHg) but did not change on 500 mg (136/77 to 133/76 mmHg) or with lifestyle advice (133/77 to 135/80 mmHg). Within twin pairs, systolic differences were up to 6 mmHg for 500 mg versus control and up to 13 mmHg for 1,000 versus 500 mg. Cholesterol fell in all groups, with dose-dependent within-pair differences in LDL cholesterol; other measures showed no consistent change. There was no placebo and no blinding.
Double-blind, randomized, parallel trial with a 4-week run-in. Participants took EFLA 943 (Benolea) 500 mg twice daily or a prescription blood pressure medicine as the active comparator for 8 weeks; there was no placebo group. Primary endpoint: change in systolic blood pressure from baseline. Trade press reported support from PT Dexa Medica and Frutarom Switzerland, the maker, and a Frutarom scientist co-authored. (Susalit et al. 2011, Phytomedicine)
Adults aged 20 to 65 with stage-1 hypertension (systolic 140 to 159 mmHg), mean age about 50, mostly women. A later meta-analysis lists 179 included and 148 completers (72 on the extract); trade reports cite 232 participants.
On the extract, systolic pressure fell 11.5 mmHg and diastolic 4.8 mmHg from a baseline of about 149/94 mmHg. Readings also fell in the comparison group, which took an active medicine. Triglycerides fell significantly on the extract but not in the comparison group. Without a placebo group, the trial cannot show how much of the drop came from the extract rather than time or repeated measurement.
Double-blind, randomized, placebo-controlled crossover trial: 6 weeks each on active and placebo tablets, taken twice daily. Each active tablet held 500 mg Benolea olive leaf extract (named in the methods), 100 mg green coffee bean extract and 150 mg beetroot powder, so the olive leaf effect cannot be separated. Primary outcome: 24-hour ambulatory blood pressure. HealthWorld Ltd funded the study and supplied the products. (Wong et al. 2014, Nutrients)
Overweight middle-aged adults with untreated high-normal or mildly raised blood pressure; 39 enrolled, 37 completed (baseline clinic blood pressure averaged 145/84 mmHg).
The trial was null: the blend had no significant effect on 24-hour blood pressure or on any other outcome, including clinic blood pressure, arterial compliance, blood lipids, glucose and insulin. A retrospective analysis by sex found lower total and HDL cholesterol in men on the blend, which was not a planned outcome. During the active phase, one person each reported vivid dreams, stomach discomfort, and more frequent headaches with existing migraine.