# Quercus ilex (Holm Oak Acorn)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/quercus-ilex
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-31
**Evidence Score:** 2 / 10
**Category:** Herb
**Also Known As:** Holm Oak acorn, Evergreen Oak acorn, Holly Oak acorn, Mediterranean Oak acorn, Spanish Oak acorn, Encina acorn, Quercus ilex acorn, Ilex Oak acorn

## Overview

Quercus ilex (Holm Oak) acorns contain polyphenols including tannins, gallic acid, and flavonoids that drive their biological activity. These compounds exert antioxidant effects by scavenging free radicals and may suppress HPV-driven tumor development through modulation of [oxidative stress](/ingredients/condition/antioxidant) pathways.

## Health Benefits

• May reduce skin lesions: In transgenic mice, oral administration reduced HPV16-induced squamous cell carcinomas at 0.06-0.09 g/mL doses (preliminary evidence, PMID: 39829663)
• Demonstrates [antioxidant activity](/ingredients/condition/antioxidant): Extract shows DPPH, superoxide, and nitric oxide scavenging properties through polyphenolic compounds (in vitro evidence only)
• Exhibits [antimicrobial](/ingredients/condition/immune-support) properties: Methanol leaf extracts inhibited 27% of 132 bacterial strains at MIC 125-500 μL/mL (in vitro evidence, PMID: 15103667)
• Supports adaptive [stress response](/ingredients/condition/stress)s: Increases C-rich metabolites like quinic acid and quercitol in response to biotic challenges (mechanistic studies only)
• May enhance biotic stress resistance: Wound-induced metabolic shifts include elevated glucose, asparagine, and choline (preclinical evidence)

## Mechanism of Action

Holm oak acorn polyphenols — including hydrolyzable tannins, gallic acid, and quercetin derivatives — donate hydrogen atoms to neutralize DPPH, superoxide, and nitric oxide radicals, reducing oxidative damage at the cellular level. In HPV16 transgenic mouse models, oral administration appeared to downregulate keratinocyte hyperproliferation and squamous cell transformation, possibly by inhibiting NF-κB-mediated [inflammatory](/ingredients/condition/inflammation) signaling and reducing [reactive oxygen species](/ingredients/condition/antioxidant) that drive oncogenic progression. Tannins may also chelate metal ions involved in Fenton-type reactions, further limiting oxidative stress.

## Clinical Summary

Current evidence for Quercus ilex acorn extract is limited to preclinical studies with no completed human clinical trials published to date. One study using HPV16 transgenic mice (PMID: 39829663) demonstrated reduced squamous cell carcinoma lesions following oral administration at concentrations of 0.06–0.09 g/mL, representing preliminary but not conclusive evidence. In vitro assays consistently show significant DPPH, superoxide, and nitric oxide scavenging activity from polyphenol-rich extracts, supporting an [antioxidant](/ingredients/condition/antioxidant) mechanism. Until randomized controlled trials in humans are conducted, all benefit claims remain speculative and should be interpreted with caution.

## Nutritional Profile

Holm Oak acorns contain moderate macronutrient content typical of Quercus species: carbohydrates ~50-60% dry weight (primarily starch ~40-50%, with some simple sugars), fats ~5-15% dry weight (oleic acid as dominant fatty acid ~55-65% of lipid fraction, linoleic acid ~15-20%, palmitic acid ~10-15%), and protein ~4-8% dry weight (containing essential amino acids including leucine, valine, and glutamic acid). Crude fiber content ranges ~3-6% dry weight. Key bioactive compounds include hydrolyzable tannins (gallotannins and ellagitannins, particularly vescalagin and castalagin) at ~2-10% dry weight depending on maturity, condensed tannins (proanthocyanidins), phenolic acids (gallic acid, ellagic acid, valoneic acid dilactone), and flavonoids (quercetin, kaempferol glycosides). Total polyphenol content reported at ~15-80 mg GAE/g dry extract depending on extraction method. Mineral content includes potassium (~300-500 mg/100g), calcium (~30-60 mg/100g), magnesium (~50-80 mg/100g), phosphorus (~100-150 mg/100g), and iron (~2-4 mg/100g). Vitamin E (tocopherols) present at low levels (~1-3 mg/100g). Bioavailability note: High tannin content significantly reduces protein digestibility and mineral absorption (particularly iron and zinc) through chelation; traditional processing (leaching, roasting) reduces tannins by 60-80% and improves nutritional bioavailability. Polyphenol bioavailability is moderate, with ellagitannins converted to urolithins by gut microbiota.

## Dosage & Preparation

No clinically studied human dosages exist. Preclinical mouse studies used acorn infusion extract at 0.03-0.09 g/mL in drinking water (approximately 0.6-1.8 g/kg/day), with efficacy observed at 0.06-0.09 g/mL over 28 days. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

No formal human safety trials have been published for Quercus ilex acorn extract, making a comprehensive adverse effect profile impossible to establish at this time. High tannin content, common in oak-derived products, may cause gastrointestinal irritation, constipation, or reduced absorption of dietary iron and certain medications such as tetracyclines and iron supplements if taken concurrently. Due to the absence of reproductive safety data, use during pregnancy or breastfeeding is not recommended. Individuals on anticoagulants or hepatotoxic medications should consult a healthcare provider, as high-dose tannin exposure has been associated with liver stress in animal models.

## Scientific Research

No human clinical trials, RCTs, or meta-analyses have been conducted on Quercus ilex acorn extract. The primary evidence comes from a 2024 mouse study (n=36) showing reduced skin lesions in HPV16-induced carcinomas (PMID: 39829663) and in vitro [antimicrobial](/ingredients/condition/immune-support) testing (PMID: 15103667).

## Historical & Cultural Context

While specific medicinal uses for Quercus ilex acorns are not documented in available sources, holm oak is a dominant species in Mediterranean agrosilvopastoral systems like the Spanish 'dehesa.' Acorns are noted for unexplored pharmacological properties and potential use as [antioxidant](/ingredients/condition/antioxidant) animal feed additives.

## Synergistic Combinations

Quercetin, Green Tea Extract, Vitamin C, Resveratrol, Grape Seed Extract

## Frequently Asked Questions

### What are the active compounds in holm oak acorn extract?

Holm oak acorns are rich in hydrolyzable tannins, gallic acid, ellagic acid, and flavonoids such as quercetin and kaempferol derivatives. These polyphenols are primarily responsible for the extract's documented antioxidant activity, including DPPH and superoxide radical scavenging. The exact concentration of each compound varies by harvest region, processing method, and extraction solvent used.

### Can holm oak acorn extract help prevent skin cancer?

In one published preclinical study (PMID: 39829663), oral administration of Quercus ilex acorn extract at 0.06–0.09 g/mL reduced HPV16-induced squamous cell carcinoma lesions in transgenic mice. This is promising preliminary data, but no human trials have replicated these findings, so it cannot be recommended as a cancer-prevention strategy. The proposed mechanism involves reducing oxidative stress and possibly suppressing keratinocyte transformation pathways.

### How does holm oak acorn extract compare to other oak-derived supplements?

Quercus ilex is a Mediterranean evergreen species distinct from common oak (Quercus robur), and its acorns have a relatively sweet, lower-tannin profile compared to deciduous oaks, making them historically consumed as food. Polyphenol profiles differ across species; Q. ilex extracts appear particularly rich in gallic acid and ellagitannins, whereas Q. robur bark extracts are more studied for anti-inflammatory applications. Direct head-to-head antioxidant comparisons between species remain limited in peer-reviewed literature.

### What is the suggested dose of holm oak acorn extract used in research?

The only published dosing reference comes from the HPV16 mouse study, which used oral concentrations of 0.06–0.09 g/mL of extract administered over a treatment period. Translating this to a human equivalent dose requires allometric scaling and has not been validated in clinical trials. There is currently no established effective or safe human dose, so supplementation guidelines cannot be responsibly provided.

### Does holm oak acorn contain gluten or common allergens?

Holm oak acorns are naturally gluten-free, as they are derived from a tree species unrelated to cereal grains. However, individuals with tree nut or general nut allergies should exercise caution, as cross-reactivity between acorn proteins and other tree nut allergens has been anecdotally reported, though formal allergy classification data for Q. ilex specifically is sparse. Those with oak pollen allergies (oral allergy syndrome) may also experience mild oral mucosal reactions due to protein cross-reactivity.

### What is the current evidence quality for holm oak acorn extract's effects on skin health?

The evidence for holm oak acorn extract is preliminary, based primarily on transgenic mouse studies showing reduced HPV16-induced skin lesions at specific oral doses (0.06-0.09 g/mL). In vitro studies demonstrate antioxidant properties through polyphenolic compounds, but human clinical trials are lacking. More research is needed before making definitive claims about its effectiveness in humans.

### Are there any safety concerns with long-term use of holm oak acorn extract?

Safety data for long-term human use of holm oak acorn extract is limited, with most evidence coming from animal models and laboratory studies. Traditional uses of oak-derived preparations exist in some cultures, but comprehensive toxicity studies in humans have not been published. Consult with a healthcare provider before sustained supplementation, especially if you have underlying health conditions.

### Can holm oak acorn extract be obtained from whole food sources rather than supplements?

Holm oak acorns are traditionally consumed in Mediterranean regions and can theoretically provide the ingredient's polyphenolic compounds through whole food consumption. However, standardized dosages and bioavailability from whole acorns are not well-documented in scientific literature. Supplement forms may offer more consistent polyphenol concentrations compared to variable acorn preparations.

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