Effects of a combination of olive leaf extract and potassium on blood pressure in participants with mild to moderate hypertension: A double blind, randomized, placebo-controlled trial.

2026-06
Phytomedicine : international journal of phytotherapy and phytopharmacology 155
- Johannes-Paul Fladerer-Grollitsch
- Franz Bucar
- Thomas Klein
- Albert Kompek
- Daniel Menzel
- Christiane Schön

PubMed: 41935461
DOI: 10.1016/j.phymed.2026.158138

Study Design

Type: Randomized Controlled Trial (RCT)
Sample size: n = 70
Population: 70 adults with untreated mildly to moderately elevated BP
Methods: randomized, double-blind, placebo-controlled study, received an OLE - potassium supplement (1000 mg OLE, ≥160 mg oleuropein, 300 mg potassium/day) or placebo for 12 weeks
Blinding: Double-blind
Duration: 12 weeks
Funding: Unclear

Background

Hypertension is a key modifiable driver of cardiovascular risk and often clusters with dyslipidemia and insulin resistance within the metabolic syndrome. Olive leaf extract (OLE) and potassium have traditionally been used to support blood pressure (BP) management and cardiometabolic health.

Purpose

To investigate the effect of this OLE - potassium combination on BP and key cardiometabolic markers.

Study design

In this randomized, double-blind, placebo-controlled study, 70 adults with untreated mildly to moderately elevated BP received an OLE - potassium supplement (1000 mg OLE, ≥160 mg oleuropein, 300 mg potassium/day) or placebo for 12 weeks.

Results

While office BP fell significantly over time in both groups, 7-day home-based BP monitoring showed a significant greater response, with morning systolic BP decreasing by 5.4 mmHg, in the verum group. Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6, while HDL-cholesterol remained stable. Fasting glucose and HbA1c were unchanged, but fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity. Additionally, oxidized LDL decreased by ∼23 %, without changes in hs-CRP. Quality-of-life scores remained stable, although global self-ratings favoured the combination. The intervention was well tolerated, with no product-related serious adverse events.

Conclusion

The combination of OLE and potassium is a safe adjunctive strategy for individuals with mildly to moderately elevated BP, with favourable effects on lipid profile, oxidative status, and insulin sensitivity that may help reduce cardiometabolic risk in the context of metabolic syndrome.

Research Insights

Olive→Improved Global Self-Rating
global self-ratings favoured the combination
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Improved Quality of Life
Quality-of-life scores remained stable
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Increased High-Density Lipoprotein Cholesterol
HDL-cholesterol remained stable
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Reduced Blood Cholesterol
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Olive→Reduced C-Reactive Protein Levels
without changes in hs-CRP
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Reduced Diastolic Blood Pressure
7-day home-based BP monitoring showed a significant greater response, with morning systolic BP decreasing by 5.4 mmHg, in the verum group.
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Olive→Reduced Fasting Blood Glucose Levels
Fasting glucose and HbA1c were unchanged
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Reduced HOMA-IR
fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Olive→Reduced Hemoglobin A1c
Fasting glucose and HbA1c were unchanged
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Reduced Insulin Levels
fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Olive→Reduced LDL Cholesterol
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Olive→Reduced Office Blood Pressure
While office BP fell significantly over time in both groups
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Olive→Reduced Oxidized Low-Density Lipoprotein Level
oxidized LDL decreased by ∼23 %
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Olive→Reduced Triglyceride Levels
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Potassium→Improved Global Self-Rating
global self-ratings favoured the combination
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Improved Insulin Sensitivity
fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Potassium→Improved Quality of Life
Quality-of-life scores remained stable
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Increased HDL Cholesterol
HDL-cholesterol remained stable
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Increased High-Density Lipoprotein Cholesterol
HDL-cholesterol remained stable
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Blood Cholesterol
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Potassium→Reduced C-Reactive Protein Levels
without changes in hs-CRP
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Diastolic Blood Pressure
7-day home-based BP monitoring showed a significant greater response, with morning systolic BP decreasing by 5.4 mmHg, in the verum group.
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Potassium→Reduced Fasting Blood Glucose Levels
Fasting glucose and HbA1c were unchanged
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Reduced HOMA-IR
fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Hemoglobin A1c
Fasting glucose and HbA1c were unchanged
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Insulin Levels
fasting insulin and HOMA-Index declined in the verum group, indicating a modest improvement in insulin sensitivity
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Potassium→Reduced LDL Cholesterol
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Office Blood Pressure
While office BP fell significantly over time in both groups
Effect
Neutral
Effect size
Small
Dose
300 mg/day
Potassium→Reduced Oxidized Low-Density Lipoprotein Level
oxidized LDL decreased by ∼23 %
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Potassium→Reduced Systolic Blood Pressure
morning systolic BP decreasing by 5.4 mmHg, in the verum group
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day
Potassium→Reduced Triglyceride Levels
Supplementation also reduced total cholesterol by 11.1 mg/dL, LDL-cholesterol by 6.9 mg/dL, and triglycerides by approximately 22 mg/dL at Week 6
Effect
Beneficial
Effect size
Moderate
Dose
300 mg/day

Adverse Events Reported

Potassium→Overall tolerability
The intervention was well tolerated, with no product-related serious adverse events.
Finding
Reported
Olive→Overall tolerability
The intervention was well tolerated, with no product-related serious adverse events.
Finding
Reported