Effectiveness of a Grape Seed Extract on Circulatory Measures in Healthy Adults

The Effectiveness of a Grape Seed Extract on Circulatory Measures in Healthy Adults: a Randomised, Double-blind, Placebo-controlled Crossover Study

This is a randomized, double-blind, placebo-controlled, 2 arm crossover study conducted over 11 weeks, with participants randomised to a product for 4 weeks, followed by a 3-week washout period before completing the second product for 4 weeks, to study the effectiveness of a grape seed extract on circulatory measures in healthy adults.

Study Overview

• Status: Completed
• Conditions: Circulatory; Change
• Intervention / Treatment: Drug: Grape Seed Extract; Drug: Maltodextrin

• Study Type: Interventional
• Enrollment (Actual): 35
• Phase: Phase 3

Contacts and Locations

Study Locations

• Australia
  • Queensland
    • Brisbane, Queensland, Australia, 4006
      • RDC Clinical Pty Ltd

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults 25 years or older
• Generally healthy
• BMI 18 - 35kg/m2
• Able to provide informed consent
• Have prehypertensive blood pressure (systolic 120-139 mmHg and/or diastolic 80-89 mmHg)
• Agree to not change current diet and/or exercise frequency or intensity during entire study period
• Agree to not participate in another clinical trial while enrolled in this trial

Exclusion Criteria:

• Those with a history of myocardial infarction, angina or bleeding disorders
• Those who have uncontrolled thyroid diseases
• Currently taking dietary supplements for circulation (e.g. fatty acids, CoQ10, L-arginine, red ginseng, ginseng, natto, ginkgo) or use of these in the last 1 month
• Currently taking inflammation or circulatory associated medications (e.g. Pentoxifylline and vasodilators like nitroglycerin) or use of these in the last 1 month
• Currently taking statins medication including atorvastatin (e.g. Lipitor, Lorstat), fluvastatin (e.g. Lescol or Vastin), pravastatin (e.g. Pravachol, Cholstat), rosuvastatin (e.g. Cavstat, Crestor) or simvastatin (e,g, Lipex, Zocor, Zimstat).
• Currently taking Coumadin, Marevan (Warfarin), Heparin, Dalteparin, Enoxaparin or other anticoagulation therapy, or substrates of P-glycoprotein including (but not limited to) calcium channel blockers, cyclosporin, digoxin, erythromycin and protease inhibitors(1).
• Have a serious illness(2) e.g. mood disorders such as bipolar disorder, neurological disorders such as MS, kidney disease, liver disease or heart conditions
• Have an unstable illness(3) (i.e., changing medication/treatment)
• Malignancy or treatment for malignancy within the previous 2 years (this excludes non-melanoma (e.g. BCC and SCC) skin cancers not requiring radiation or chemotherapy)
• Active smokers, nicotine use or drug (prescription or illegal substances) abuse
• Chronic past and/or current alcohol use (>14 alcoholic drinks week)
• Allergic to any of the ingredients in active or placebo formula
• Pregnant or lactating woman or women trying to conceive
• Any condition which in the opinion of the investigator makes the participant unsuitable for inclusion

• Participated in another trial in the past 1 month

  1. Any participant that begins taking antiplatelet medication during the trial will be excluded from the study
  2. A serious illness is a condition that carries a risk of mortality, negatively impacts quality of life and daily function and/or is burdensome in symptoms and/or treatments.
  3. An unstable illness is any illness that is currently not being treated with a stable dose of medication or is fluctuating in severity.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Grape Seed Extract; Grape seed extract 600mg per day - 1 capsule per day	Drug: Grape Seed Extract; One daily dose of 1 capsule containing 600mg grape seed extract
Placebo Comparator: Maltodextrin; Maltodextrin - 1 capsule per day	Drug: Maltodextrin; One daily dose of 1 capsule

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Diastolic blood pressure (arm)	Change in Diastolic blood pressure (arm) as measured by blood pressure machine	Baseline, week 4, week 8, week 11

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Systolic blood pressure (arm)	Change in Systolic blood pressure (arm) as measured by blood pressure machine	Baseline, week 4, week 8, week 11
Change in Peripheral systolic and diastolic blood pressure (leg)	Change in Peripheral systolic and diastolic blood pressure (leg) as measured by blood pressure machine	Baseline, week 4, week 8, week 11
Change in HGB	Change in HGB as measured by FBC via blood test	Baseline, week 4, week 8, week 11
Change in WBC	Change in WBC as measured by FBC via blood test	Baseline, week 4, week 8, week 11
Change in RBC	Change in RBC as measured by FBC via blood test	Baseline, week 4, week 8, week 11
Change in Platelet Aggregation	Change in Platelet Aggregation as measured by FBC via blood test	Baseline, week 4, week 8, week 11
Change in (endothelial nitric oxide synthase) eNOS	Change in eNOS as measured via blood test	Baseline, week 4, week 8, week 11
Change in endogenous nitric oxide (NO)	Change in NO as measured via blood test	Baseline, week 4, week 8, week 11
Change in Tibial artery structure	Change in Tibial artery structure via Laser Doppler Flowmetry	Baseline, week 4, week 8, week 11
Change in blood flow of the right leg	Change in blood flow of the right leg via Laser Doppler Flowmetry	Baseline, week 4, week 8, week 11
Change in oxygen saturation	Change in oxygen saturation as measured by pulse oximeter	Baseline, week 4, week 8, week 11
Change in resting pulse rate	Change in resting pulse rate as digital blood pressure and resting pulse rate machine	Baseline, week 4, week 8, week 11
Change in weight	Change in weight as measure by digital scales	Baseline, week 4, week 8, week 11
Change in Body Mass Index (BMI)	Change in BMI as measured by weight and height calculation	Baseline, week 4, week 8, week 11
Change in waist and hip circumference	Change in waist and hip circumference as measured by tape measure	Baseline, week 4, week 8, week 11
Change in 36-Item Short Form Health Survey (SF-36)	Change in 36-Item Short Form Health Survey (SF-36) as self-reported	Baseline, week 4, week 8, week 11
Change in E/LFT	Change in E/LFT as measured via blood test	Baseline, week 4, week 8, week 11
Change in triglycerides	Change in triglycerides as measured via blood test	Baseline, week 4, week 8, week 11
Change in cholesterol	Change in cholesterol as measured via blood test	Baseline, week 4, week 8, week 11
Change in blood glucose	Change in blood glucose as measured via blood test	Baseline, week 4, week 8, week 11
Change in adverse events	Change in adverse events as reported by participant	Baseline, week 4, week 8, week 11

Collaborators and Investigators

• Sponsor: RDC Clinical Pty Ltd
• Investigators: Principal Investigator: Amanda Rao, PhD, RDC Clinical Pty Ltd

Study record dates

Study Major Dates

• Study Start (Actual): October 31, 2024
• Primary Completion (Actual): December 31, 2025
• Study Completion (Actual): December 31, 2025

Study Registration Dates

• First Submitted: May 17, 2024
• First Submitted That Met QC Criteria: May 28, 2024
• First Posted (Actual): June 3, 2024

Study Record Updates

• Last Update Posted (Actual): March 6, 2026
• Last Update Submitted That Met QC Criteria: March 4, 2026
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pharmaceutical Preparations; Plant Extracts; Plant Preparations; Biological Products; Complex Mixtures; Grape Seed Extract; maltodextrin
• Other Study ID Numbers: ALVCIR

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No