Grape seed extract's effects on circulation in healthy adults

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

Phase 3 Interventional RDC Clinical Pty Ltd · NCT06440252

This study is testing if grape seed extract can improve circulation in healthy adults who have slightly high blood pressure.

Quick facts

PhasePhase 3
Study typeInterventional
Enrollment150 (estimated)
Ages25 Years and up
SexAll
SponsorRDC Clinical Pty Ltd Industry-sponsored
Drugs / interventionschemotherapy, radiation
Locations1 site (Brisbane, Queensland)
Trial IDNCT06440252 on ClinicalTrials.gov

What this trial studies

This interventional study is a randomized, double-blind, placebo-controlled, 2-arm crossover trial that lasts for 11 weeks. Participants, aged 25 and older, will be assigned to receive either grape seed extract or a placebo for 4 weeks, followed by a 3-week washout period, and then switch to the other product for another 4 weeks. The study aims to evaluate the effectiveness of grape seed extract on various circulatory measures in generally healthy adults with prehypertensive blood pressure.

Who should consider this trial

Good fit: Ideal candidates are generally healthy adults aged 25 years or older with prehypertensive blood pressure.

Not a fit: Patients with a history of cardiovascular issues or those currently taking specific circulatory-related medications may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into natural supplements for improving circulatory health in adults.

How similar studies have performed: While there is limited information on similar studies, the use of natural supplements for circulatory health has shown promise in some previous research.

Eligibility criteria

Show full inclusion / exclusion criteria
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.

Where this trial is running

Brisbane, Queensland

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions CirculatoryChange
Last reviewed 2026-06-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.