# Fraxinus excelsior

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/fraxinus-excelsior
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-04-02
**Evidence Score:** 2 / 10
**Category:** Other
**Also Known As:** Common ash, European ash, Ash tree, Common European ash, White ash, Weeping ash, Frêne commun, Gemeine Esche, Fresno común

## Overview

Fraxinus excelsior (common ash) contains active secoiridoid glycosides, particularly oleuropein and nuzhenide in its seeds, which modulate glucose metabolism by inhibiting intestinal alpha-glucosidase activity and improving [insulin sensitivity](/ingredients/condition/weight-management). Clinical evidence supports its seed extract for reducing postprandial blood glucose spikes, while leaf preparations show antihypertensive effects likely mediated through ACE inhibition and calcium channel antagonism.

## Health Benefits

• Improved glucose tolerance: Seed extract reduced post-meal glucose AUC by 28.2% in overweight adults (moderate evidence, PMID: 24877717)
• [Blood pressure](/ingredients/condition/heart-health) support: Aqueous leaf extract reduced systolic blood pressure by 13.5% in hypertensive rats at 20 mg/kg (preliminary evidence, animal studies only)
• Enhanced metabolic health: Increased adiponectin:leptin ratio and reduced fat mass in human trial (moderate evidence, PMID: 24877717)
• [Anti-inflammatory](/ingredients/condition/inflammation) activity: Leaf compounds reduced TNF-α and IL-6 comparable to dexamethasone in vitro (preliminary evidence, cell studies only)
• Diuretic effects: Increased urinary electrolyte excretion and glomerular filtration rate in rats (preliminary evidence, animal studies only)

## Mechanism of Action

The secoiridoid glycosides in Fraxinus excelsior seeds, including nuzhenide and GI3, inhibit intestinal alpha-glucosidase enzymes, slowing carbohydrate [digestion](/ingredients/condition/gut-health) and blunting postprandial glucose absorption. Leaf-derived compounds, including fraxin (a coumarin glycoside) and hydroxycinnamic acid derivatives, appear to inhibit angiotensin-converting enzyme (ACE) and antagonize voltage-gated calcium channels in vascular smooth muscle, contributing to vasodilation. Additionally, polyphenolic constituents may enhance GLUT4 translocation and improve peripheral insulin signaling through AMPK pathway activation.

## Clinical Summary

A randomized, double-blind, placebo-controlled crossover trial (PMID: 24877717) in overweight adults demonstrated that Fraxinus excelsior seed extract reduced postprandial glucose area under the curve (AUC) by 28.2%, representing the strongest human clinical evidence for this ingredient. Animal studies in hypertensive rat models showed that aqueous leaf extract at 20 mg/kg reduced systolic [blood pressure](/ingredients/condition/heart-health) by approximately 13.5%, though these findings have not yet been replicated in human trials. The seed extract evidence is classified as moderate quality given its controlled design, but sample sizes remain small and long-term safety data in humans are lacking. Overall, the evidence base is promising but preliminary, particularly for the antihypertensive applications.

## Nutritional Profile

Fraxinus excelsior (European Ash) contains bioactive compounds concentrated across seeds, leaves, and bark. Seeds contain secoiridoid glycosides including nuzhenide (primary bioactive, ~0.5-2% dry weight) and GI3 (nuzhenide-11-methyl oleuropein), which are responsible for glucose-lowering effects. Leaves are rich in hydroxycoumarins, primarily fraxin and esculin (0.1-0.5% dry weight), alongside flavonoids including rutin (~0.3-0.8% dry weight) and quercetin derivatives. Polyphenolic content includes chlorogenic acids and caffeic acid esters (~1-3% dry weight in leaf extracts). Leaves also contain iridoids (oleoside-type), mannitol (~5-10% dry weight, a sugar alcohol with [prebiotic](/ingredients/condition/gut-health) properties), and small amounts of tannins. Bark contains fraxetin (a coumarin), syringin (a phenylpropanoid glycoside), and lignans. Mineral content in leaves includes potassium (~15-20 mg/g dry weight), calcium (~12-18 mg/g dry weight), and magnesium (~3-5 mg/g dry weight). Vitamin C is present in modest amounts (~20-40 mg/100g fresh leaf). Fiber content is notable in seeds (~15-25% dry weight), contributing to the delayed glucose absorption mechanism. Bioavailability of secoiridoids is enhanced by gut microbiota hydrolysis; polyphenol absorption is moderate (~10-30%) and improved with food matrix co-ingestion.

## Dosage & Preparation

Clinically studied doses include 1000 mg/day of FraxiPure™ leaf extract for 90 days (safety) or 1000 mg/day Glucevia® seed extract (3 × 333 mg capsules) for 3 weeks (metabolic effects). Preclinical studies used 20-200 mg/kg in rats. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Fraxinus excelsior is generally considered well-tolerated at studied doses, with no serious adverse events reported in available clinical trials, though comprehensive human safety data remain limited. Due to its alpha-glucosidase inhibitory activity, concurrent use with antidiabetic medications such as metformin, sulfonylureas, or acarbose may potentiate hypoglycemic effects, warranting [blood glucose](/ingredients/condition/weight-management) monitoring. Its potential ACE-inhibitory and vasodilatory properties suggest caution when combined with antihypertensive drugs, as additive [blood pressure](/ingredients/condition/heart-health) lowering could occur. Insufficient data exist to establish safety during pregnancy or lactation, so use should be avoided in these populations until further evidence is available.

## Scientific Research

Human clinical evidence is limited to two RCTs: a 90-day safety study with 100 healthy volunteers showing no adverse effects at 1000 mg/day FraxiPure™ (PMID: 23201448), and a 3-week crossover trial in 22 overweight adults demonstrating significant glucose-lowering effects with Glucevia® seed extract (PMID: 24877717). No meta-analyses or large-scale human trials exist for [cardiovascular](/ingredients/condition/heart-health) or [anti-inflammatory](/ingredients/condition/inflammation) effects.

## Historical & Cultural Context

Fraxinus excelsior has long-term use in European phytotherapy for conditions including [inflammation](/ingredients/condition/inflammation), hypertension, and metabolic issues. Traditional applications also include bark extracts for antimalarial purposes, with modern studies confirming in vitro activity against Plasmodium falciparum.

## Synergistic Combinations

Chromium picolinate, Gymnema sylvestre, Bitter melon extract, Alpha-lipoic acid, Cinnamon extract

## Frequently Asked Questions

### What is the effective dose of Fraxinus excelsior seed extract for blood sugar control?

The clinical trial demonstrating a 28.2% reduction in postprandial glucose AUC (PMID: 24877717) used a standardized seed extract, though exact milligram dosages vary by product formulation and standardization level of secoiridoid glycosides such as nuzhenide. Most commercial extracts are standardized to a defined percentage of these active glycosides, and consumers should verify the standardization certificate before use. Consulting a healthcare provider is recommended to determine an appropriate dose alongside dietary management.

### How does Fraxinus excelsior lower blood sugar after meals?

Fraxinus excelsior seed extract contains secoiridoid glycosides, primarily nuzhenide and GI3, that inhibit intestinal alpha-glucosidase enzymes responsible for breaking down complex carbohydrates into absorbable sugars. By slowing this enzymatic step, glucose enters the bloodstream more gradually, reducing the sharp postprandial glucose spike. This mechanism is similar to the pharmaceutical drug acarbose, though the potency and selectivity differ and direct comparative trials have not been conducted.

### Can Fraxinus excelsior lower blood pressure?

Preliminary animal research found that an aqueous leaf extract of Fraxinus excelsior reduced systolic blood pressure by approximately 13.5% in hypertensive rats at a dose of 20 mg/kg, suggesting antihypertensive potential. The proposed mechanisms involve ACE inhibition and calcium channel antagonism by fraxin and hydroxycinnamic acid derivatives found in the leaves. However, human clinical trials confirming these blood pressure effects are currently lacking, so these findings cannot yet be directly applied to human supplementation recommendations.

### What are the active compounds in Fraxinus excelsior?

The seeds of Fraxinus excelsior are rich in secoiridoid glycosides, particularly nuzhenide and GI3, which are primarily responsible for its glucose-lowering effects through alpha-glucosidase inhibition. The leaves contain fraxin (a coumarin glycoside), esculin, hydroxycinnamic acids, and flavonoids, which contribute to antihypertensive and antioxidant activities. The differing phytochemical profiles of seeds versus leaves mean that the two plant parts have distinct pharmacological targets and evidence bases.

### Does Fraxinus excelsior interact with diabetes or blood pressure medications?

Because Fraxinus excelsior seed extract inhibits alpha-glucosidase similarly to the drug acarbose, combining it with antidiabetic medications such as metformin, sulfonylureas, insulin, or acarbose itself may produce additive hypoglycemic effects and increase the risk of low blood sugar. Its leaf extract's potential ACE-inhibitory and vasodilatory actions could enhance the effects of antihypertensive drugs like lisinopril or amlodipine, raising the risk of excessive blood pressure reduction. Anyone taking medications for diabetes or hypertension should consult a physician before adding Fraxinus excelsior supplements.

### Is Fraxinus excelsior safe during pregnancy and breastfeeding?

There is insufficient clinical data to establish the safety of Fraxinus excelsior supplementation during pregnancy and breastfeeding. Due to lack of adequate human studies, supplementation should be avoided during these periods unless specifically recommended by a healthcare provider. Pregnant and nursing women should consult their physician before using any Fraxinus excelsior products.

### What is the strongest form of Fraxinus excelsior extract for metabolic health?

Seed extract appears to be the most studied and effective form, with clinical evidence showing a 28.2% reduction in post-meal glucose AUC in overweight adults. While aqueous leaf extracts have shown promise in animal models for blood pressure support, human clinical data is limited primarily to seed extract formulations. The standardization and extract method significantly influence bioavailability and efficacy.

### Who is most likely to benefit from Fraxinus excelsior supplementation?

Overweight or prediabetic individuals seeking glucose control support appear to be the primary candidates, based on clinical evidence showing improved post-meal glucose tolerance. Those with metabolic health concerns may also benefit from improved adiponectin:leptin ratios and reduced fat mass, as documented in human trials. Individuals with hypertension should consult a healthcare provider, as current evidence is limited to animal studies.

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