# GLPH-1 (Grapeseed Polyphenol)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/glph-1
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-02
**Evidence Score:** 2 / 10
**Category:** Other
**Also Known As:** Vitis vinifera seed extract, Standardized grape seed polyphenol extract, Grape seed proanthocyanidin extract, GSE polyphenol standardized, Grapeseed oligomeric proanthocyanidins, Wine grape seed extract

## Overview

GLPH-1 is a standardized grapeseed polyphenol extract characterized by a proanthocyanidin content exceeding 95%, where these oligomeric proanthocyanidins act as potent free-radical scavengers and may modulate endothelial nitric oxide synthase (eNOS) activity to support [vascular tone](/ingredients/condition/heart-health). Its cognitive health classification stems from proposed [neuroprotective effect](/ingredients/condition/cognitive)s linked to reduced [oxidative stress](/ingredients/condition/antioxidant) in neuronal tissue, though direct human clinical trials specific to the GLPH-1 designation remain limited.

## Health Benefits

• May support [cardiovascular health](/ingredients/condition/heart-health) (evidence from similar grape seed extracts suggests pre-hypertension benefits, though specific GLPH-1 trials are lacking)
• Potential [antioxidant activity](/ingredients/condition/antioxidant) from proanthocyanidin content (>95% polyphenol standardization achieved, but direct clinical evidence not available)
• Possible post-meal glycemic response support (general grape seed extract data from UC Davis, not GLPH-1 specific)
• May help maintain healthy LDL cholesterol levels (suggested by related grape seed research, no direct GLPH-1 studies)
• [Cognitive](/ingredients/condition/cognitive) health support (categorized under this group, though specific clinical evidence for GLPH-1 is absent)

## Mechanism of Action

GLPH-1's oligomeric proanthocyanidins (OPCs) scavenge [reactive oxygen species](/ingredients/condition/antioxidant) (ROS) by donating hydrogen atoms to neutralize superoxide and hydroxyl radicals, inhibiting lipid peroxidation cascades. These OPCs also upregulate endothelial nitric oxide synthase (eNOS) expression, increasing nitric oxide (NO) bioavailability to promote vasodilation and reduce vascular resistance. Additionally, proanthocyanidins may inhibit NADPH oxidase activity and downregulate NF-κB [inflammatory](/ingredients/condition/inflammation) signaling, which is theorized to contribute to [neuroprotective effect](/ingredients/condition/cognitive)s relevant to its cognitive health category.

## Clinical Summary

Direct randomized controlled trials using the specific GLPH-1 designation are not currently available in peer-reviewed literature, limiting definitive efficacy claims. However, closely related standardized grapeseed extracts (GSE) with comparable OPC profiles have been studied in small human trials; a meta-analysis of 16 randomized trials (n=810) found GSE supplementation significantly reduced systolic [blood pressure](/ingredients/condition/heart-health) by approximately 6.08 mmHg and diastolic blood pressure by 2.8 mmHg in pre-hypertensive individuals. [Antioxidant](/ingredients/condition/antioxidant) outcomes in these trials, measured via plasma ORAC values and F2-isoprostane reduction, showed statistically significant improvements at doses ranging from 150–300 mg/day over 4–12 weeks. Evidence quality is moderate, and extrapolation from generic GSE data to GLPH-1 specifically must be done cautiously until proprietary trials are published.

## Nutritional Profile

GLPH-1 is a highly concentrated grapeseed polyphenol extract standardized to >95% total polyphenol content, meaning it is not a whole-food ingredient and contains negligible macronutrients (protein, fat, carbohydrates) or conventional micronutrients in functional doses. Bioactive composition is dominated by oligomeric proanthocyanidins (OPCs), primarily procyanidin B1, procyanidin B2, procyanidin C1, and procyanidin B2-3-O-gallate, which are the characteristic dimeric and trimeric flavan-3-ol units of grape seed extracts. Monomeric flavan-3-ols including (+)-catechin and (-)-epicatechin are present as minor constituents, typically comprising 2–5% of the polyphenol fraction in high-OPC standardized extracts. Gallic acid and its derivatives contribute to the gallate-esterified procyanidin pool. The >95% standardization level distinguishes GLPH-1 from standard grape seed extracts (commonly 85–90% polyphenols), suggesting a more refined, higher-purity extract with reduced non-polyphenol plant matrix content (waxes, lipids, sugars). Bioavailability of grape seed OPCs is molecular-weight dependent: monomers (catechin, epicatechin) are well-absorbed in the small intestine with bioavailability estimates of 20–50%; dimers show moderate absorption; higher-order oligomers and polymers (>4 units) are poorly absorbed intact and undergo colonic microbial biotransformation into smaller phenolic acids (e.g., 3-O-methyl gallic acid, hydroxyphenylpropionic acid derivatives) that are systemically absorbed. Caloric contribution is negligible at typical supplemental doses (100–300 mg). No significant fiber, vitamin, or mineral content is expected at these concentrations.

## Dosage & Preparation

No clinically studied dosage ranges for GLPH-1 are available. Extraction processes yield >95% polyphenol content with oligomeric procyanidins comprising >98% of procyanidins, but human dosing recommendations have not been established. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Standardized grapeseed polyphenol extracts are generally well tolerated at doses up to 300 mg/day, with the most commonly reported adverse effects being mild gastrointestinal discomfort, headache, and dizziness observed in a minority of participants in clinical trials. GLPH-1's OPCs may potentiate the anticoagulant effect of warfarin and other blood thinners by inhibiting platelet aggregation and modulating thromboxane A2 synthesis, requiring caution and possible INR monitoring in patients on anticoagulant therapy. Co-administration with chemotherapy agents metabolized via CYP2C9 and CYP3A4 pathways warrants caution, as proanthocyanidins may inhibit these enzymes. Safety data in pregnant or breastfeeding individuals is insufficient, and use during pregnancy is not recommended without physician guidance.

## Scientific Research

No specific human clinical trials, RCTs, or meta-analyses directly on GLPH-1 were found in the provided research. General grape seed extract studies from UC Davis indicate potential benefits for pre-hypertension, glycemic response, and [LDL cholesterol](/ingredients/condition/heart-health), but these lack specific study designs, sample sizes, or PMIDs and cannot be directly attributed to GLPH-1.

## Historical & Cultural Context

No historical or traditional medicine context was found for GLPH-1 or grape seed polyphenols in the provided research. The ingredient appears to be a modern branded extract without documented traditional use in systems like Ayurveda or TCM.

## Synergistic Combinations

Resveratrol, Quercetin, Vitamin C, CoQ10, Maritime Pine Bark Extract

## Frequently Asked Questions

### What is GLPH-1 grapeseed polyphenol and how is it different from regular grape seed extract?

GLPH-1 is a proprietary grapeseed polyphenol fraction standardized to contain greater than 95% total polyphenols, with oligomeric proanthocyanidins (OPCs) as the primary bioactives, which is a higher standardization threshold than many commercial grape seed extracts that range from 40–85% OPC content. This higher concentration is intended to deliver more consistent antioxidant and vascular-modulating activity per dose. However, because it is a branded designation, independent third-party clinical trials specifically validating GLPH-1 over generic GSE are not yet widely published.

### What is the recommended dosage of GLPH-1 grapeseed polyphenol?

No GLPH-1-specific clinical dosing protocol has been established in published human trials as of current literature. Based on comparable standardized grapeseed extract studies, effective doses typically ranged from 150 to 300 mg per day, often split into two administrations with meals to improve tolerability. Consumers should follow manufacturer labeling and consult a healthcare provider, particularly at higher doses, due to potential interactions with anticoagulant medications.

### Can GLPH-1 grapeseed polyphenol improve memory or cognitive function?

GLPH-1 is categorized under cognitive health based on mechanistic evidence showing that proanthocyanidins can cross the blood-brain barrier and reduce neuronal oxidative stress by scavenging ROS and suppressing NF-κB-driven neuroinflammation. Animal studies using comparable OPC-rich extracts have demonstrated improved spatial memory performance in rodent models of oxidative stress-induced cognitive decline. Direct human clinical trials measuring cognitive endpoints for GLPH-1 specifically have not been published, so cognitive benefit claims remain preliminary and mechanism-driven rather than clinically confirmed.

### Is GLPH-1 grapeseed polyphenol safe to take with blood pressure medications?

OPCs in grapeseed extracts like GLPH-1 may produce an additive blood pressure-lowering effect by increasing nitric oxide bioavailability via eNOS upregulation, which could amplify the effect of antihypertensive drugs such as ACE inhibitors, ARBs, or calcium channel blockers. This combination is not strictly contraindicated but warrants monitoring for hypotension, especially in the first weeks of co-use. Patients on antihypertensive therapy should inform their prescribing physician before adding GLPH-1 to their regimen.

### Does GLPH-1 grapeseed polyphenol interact with warfarin or blood thinners?

Yes, proanthocyanidins found in GLPH-1 have demonstrated in vitro and limited in vivo capacity to inhibit platelet aggregation by suppressing thromboxane A2 synthesis and reducing collagen-induced platelet activation, which may potentiate the anticoagulant effect of warfarin, aspirin, clopidogrel, or novel oral anticoagulants (NOACs). Concurrent use could theoretically increase bleeding risk, particularly at doses above 150 mg/day. Patients taking any anticoagulant or antiplatelet therapy should consult their physician and may require INR monitoring if combining these agents.

### What is the difference between GLPH-1 and other standardized grape seed extracts on the market?

GLPH-1 is a branded grape seed polyphenol extract standardized to >95% polyphenol content, which represents a higher concentration than many conventional grape seed extracts that typically range from 40-90% polyphenols. This higher standardization may provide more concentrated proanthocyanidins per serving, though independent clinical trials directly comparing GLPH-1 to other branded extracts are limited. The specific extraction and stabilization process used for GLPH-1 may affect its bioavailability and efficacy compared to non-standardized or differently processed grape seed sources.

### Can I get the same polyphenol content from eating grapes or grape juice instead of taking GLPH-1 supplements?

While whole grapes and grape juice contain polyphenols, you would need to consume large quantities daily to match the concentrated levels found in a single GLPH-1 dose (which is standardized to >95% polyphenols). Fresh grapes typically contain only 50-100 mg of polyphenols per serving, whereas GLPH-1 supplements can deliver 150-300+ mg depending on formulation and dosage. Additionally, the polyphenol profile and bioavailability of concentrated extracts may differ from whole food sources due to processing and standardization.

### Is GLPH-1 grapeseed polyphenol safe for pregnant women or nursing mothers?

There is insufficient safety data on GLPH-1 specifically in pregnant or nursing populations, so it is generally recommended that these groups avoid supplementation unless directed by a healthcare provider. While grape seed extract has been studied in some populations, the high polyphenol concentration in GLPH-1 and potential effects on hormone levels or fetal development have not been adequately researched. Pregnant and nursing women should consult their obstetrician before taking any grape seed polyphenol supplement.

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*Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com*
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