Grape Seed Extract

foundation

Abstract

Grape Seed Extract contains high concentrations of proanthocyanidins — potent antioxidant compounds that support cardiovascular health. These polyphenols work through multiple mechanisms: neutralizing free radicals, reducing inflammation, and may improve blood vessel function through enhanced nitric oxide production. Better blood flow supports energy and physical performance.

We standardize our extract to 95% polyphenols, ensuring consistent potency of the active compounds in every dose. That standardization matters — raw grape seed extract varies widely in composition, so locking in the polyphenol content is what separates a reliable ingredient from a label claim.

The statements on this page have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Grape Seed Benefits — What Studies Found

No ingredient works if blood can’t carry it where it’s needed. Grape seed extract supports circulation and nitric oxide production from the ground up.

-38%

Anti-Inflammatory

hsCRP (at 600mg, Diabetics)

Anti-Inflammatory

Study in type 2 diabetics at 600mg/day — RBRN uses 150mg (1/4 the study dose). See full context below.

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+52%

Antioxidant Defense

Glutathione (at 600mg, Diabetics)

Antioxidant Defense

Same 600mg study in diabetics (RBRN uses 150mg). See the full findings and dose context below.

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↑ Aromatase

Aromatase Inhibition

Lab Research

Aromatase Inhibition

Laboratory research only — not confirmed in human studies. See what the in vitro data shows below.

View study →

Why a 150mg dose of Grape Seed Extract

Clinical studies showing cardiovascular benefits use doses ranging from 100-300mg of standardized grape seed extract. Our 150mg sits in the middle of this effective range.

  • Mid-Range Dose 150mg sits within the 100-300mg range used in clinical trials on blood pressure and endothelial function.
  • 95% Polyphenol Standardization Ensures a consistent, concentrated dose of proanthocyanidins rather than variable raw seed material.
  • Dual-Purpose Ingredient Supports cardiovascular health and blood flow while also contributing aromatase-inhibiting properties relevant to hormone balance.
  • Consistent Study Outcomes Blood pressure reduction and antioxidant effects are among the more reliably demonstrated findings in grape seed research.

Clinical Dose Range

0mg
100mg 150mg 300mg
500mg

Clinical studies use 100–300mg of standardized extract. Our 150mg at 95% polyphenols delivers potent antioxidant support within the effective range.

Grape Seed Extract in its natural environment
Grape Seed ExtractCardiovascular & Antioxidant Defense

Proanthocyanidins support nitric oxide and vascular function — the circulation that carries every other ingredient to where it needs to go.

What the Research Shows

Grape seed extract has about 20 clinical studies examining cardiovascular and metabolic effects. The evidence for blood pressure and antioxidant support is promising. The aromatase-inhibiting properties add an interesting dimension for men’s health, though more human studies specifically examining hormone effects would strengthen this area.

5 peer-reviewed studies cited· See all 29 published studies →

02

Endothelial Function

Clifton PM. (2004). Journal of Biomedicine & Biotechnology. Source

Research shows grape seed extract improves flow-mediated dilation—a measure of how well blood vessels relax and expand. This indicates better endothelial function and nitric oxide availability.

03

Inflammation and Metabolic Markers

Kar P, et al. (2009). Diabetic Medicine. Source

In type 2 diabetics at high cardiovascular risk, grape seed extract (at 600mg/day — four times our 150mg dose) significantly improved markers of inflammation (hsCRP decreased ~38%), blood glucose (fructosamine), and glutathione levels (increased ~52%). Effects at lower doses have not been separately studied.

04

Aromatase Inhibition

Kijima I, et al. (2006). Cancer Research. Source

Laboratory studies demonstrate that grape seed extract inhibits aromatase activity and suppresses aromatase expression. This may help maintain testosterone-to-estrogen balance by reducing testosterone conversion.

05

Antioxidant Capacity

Nuttall SL, et al. (1998). Journal of Clinical Pharmacy and Therapeutics. Source

In a small 5-day trial (n=20), grape seed extract increased serum total antioxidant capacity, suggesting potential systemic antioxidant benefits.

Published Research

29 studies

Every claim we make is grounded in peer-reviewed research. Tap any study to read the abstract.

Year Title Journal
  1. 2024The effects of grape seed extract supplementation on cardiovascular risk factors, liver enzymes and hepatic steatosis in patients with non-alcoholic fatty liver disease: a randomised, double-blind, placebo-controlled study.BMC complementary medicine and therapies
  2. 2023Comparative effects of nutraceuticals on body weight in adults with overweight or obesity: A systematic review and network meta-analysis of 111 randomized clinical trials.Pharmacological research
  3. 2023Iron Deficiency Anemia in Infancy, Childhood, and Adolescence.Turkish archives of pediatrics
  4. 2023The effect of grape seed procyanidins extract on cognitive function in elderly people with mild cognitive impairment: A randomized, double-blind, placebo-controlled clinical trial.Heliyon
  5. 2023Effects of a polyphenol-rich grape and blueberry extract (Memophenol™) on cognitive function in older adults with mild cognitive impairment: A randomized, double-blind, placebo-controlled study.Frontiers in psychology
  6. 2023A grape seed and bilberry extract reduces blood pressure in individuals at risk of developing type 2 diabetes: the PRECISE study, a double-blind placebo-controlled cross-over intervention study.Frontiers in nutrition
  7. 2022The effect of grape products on liver enzymes: A systematic review and meta-analysis of randomized controlled trials.Phytotherapy research : PTR
  8. 2020Effects of grape seed extract on dyslipidaemia: a systematic review and dose-response meta-analysis of randomised controlled trials.The British journal of nutrition
  9. 2020Grape seed extract: having a potential health benefits.Journal of food science and technology
  10. 2020The effects of grape seed extract on glycemic control, serum lipoproteins, inflammation, and body weight: A systematic review and meta-analysis of randomized controlled trials.Phytotherapy research : PTR
  11. 2019Effect of grape seed proanthocyanidin extract on hard exudates in patients with non-proliferative diabetic retinopathy.Medicine
  12. 2019Dual Anticoagulant/Antiplatelet Activity of Polyphenolic Grape Seeds Extract.Nutrients
  13. 2017Safety assessment of 4-week oral intake of proanthocyanidin-rich grape seed extract in healthy subjects.Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association
  14. 2017Masquelier's grape seed extract: from basic flavonoid research to a well-characterized food supplement with health benefits.Nutrition journal
  15. 2016The impact of grape seed extract treatment on blood pressure changes: A meta-analysis of 16 randomized controlled trials.Medicine
  16. 2015Chemical investigation of commercial grape seed derived products to assess quality and detect adulteration.Food chemistry
  17. 2013Proanthocyanidin-rich grape seed extract reduces leg swelling in healthy women during prolonged sitting.Journal of the science of food and agriculture
  18. 2012Variable inhibitory effect of herbal supplements of different brands on human P450 CYP1A2.EXCLI journal
  19. 2011The effect of grape seed extract on cardiovascular risk markers: a meta-analysis of randomized controlled trials.Journal of the American Dietetic Association
  20. 2009Effect of grape seed extract on blood pressure in subjects with the metabolic syndrome.Metabolism: clinical and experimental
  21. 2009Effects of grape seed extract in Type 2 diabetic subjects at high cardiovascular risk: a double blind randomized placebo controlled trial examining metabolic markers, vascular tone, inflammation, oxidative stress and insulin sensitivity.Diabetic medicine : a journal of the British Diabetic Association
  22. 2007An in vitro evaluation of cytochrome P450 inhibition and P-glycoprotein interaction with goldenseal, Ginkgo biloba, grape seed, milk thistle, and ginseng extracts and their constituents.Planta medica
  23. 2007Effects of grape seed extract consumption on platelet function in postmenopausal women.Thrombosis research
  24. 2006Grape seed extract is an aromatase inhibitor and a suppressor of aromatase expression.Cancer research
  25. 2004Oral intake of proanthocyanidin-rich extract from grape seeds improves chloasma.Phytotherapy research : PTR
  26. 2004The effect of grape-seed extract on 24 h energy intake in humans.European journal of clinical nutrition
  27. 2004Effect of Grape Seed Extract and Quercetin on Cardiovascular and Endothelial Parameters in High-Risk Subjects.Journal of biomedicine & biotechnology
  28. 2003Effect of a standardized grape seed extract on low-density lipoprotein susceptibility to oxidation in heavy smokers.Metabolism: clinical and experimental
  29. 1998An evaluation of the antioxidant activity of a standardized grape seed extract, Leucoselect.Journal of clinical pharmacy and therapeutics

Our Assessment: Grape Seed Extract

Growing Evidence
Evidence Rating

Good clinical evidence for blood pressure and antioxidant support. The aromatase-inhibiting properties are shown in lab research but haven't been confirmed in human hormone studies yet.

What’s Solid
  • Blood pressure reduction is demonstrated in clinical trials
  • Antioxidant activity is well-documented
  • Endothelial function improvements are measurable
  • Aromatase inhibition is shown in laboratory research
What Needs More Research
  • Long-term cardiovascular outcome studies
  • Translation of aromatase inhibition findings to meaningful hormone effects in humans
  • Optimal dosing for different goals
  • Direct comparisons with other cardiovascular compounds

How Grape Seed Fits the Formula

No ingredient works alone. Grape Seed was chosen because it amplifies — and is amplified by — specific formula partners.

Grape Seed

Safety and Precautions

Considerations
Grape seed extract is generally well tolerated with minimal side effects in clinical trials.
Blood thinning
May have mild effects on platelet aggregation. Those on anticoagulant medications (warfarin, aspirin, etc.) should consult their healthcare provider.
Surgery
As with many supplements affecting blood clotting, consider discontinuing before scheduled surgery.
Pregnancy and lactation
Limited safety data; caution is advised.

Always consult with a healthcare professional before starting any new dietary supplement, especially if you have an existing medical condition or take prescription medications.

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