# Gyokuro (Camellia sinensis)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/gyokuro
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-24
**Evidence Score:** 2 / 10
**Category:** Tea Cultivars
**Also Known As:** Camellia sinensis, Jade Dew, Pearl Dew, Gyokuro-cha, Tamaryokucha, Shaded green tea, Premium sencha, Uji-cha

## Overview

Gyokuro is a shade-grown Japanese green tea (Camellia sinensis) cultivated under 20–30 days of covered canopy, which restricts photodegradation and elevates concentrations of L-theanine, EGCG, and chlorophyll relative to sun-grown teas. The combination of EGCG-mediated inhibition of catechol-O-methyltransferase (COMT) and L-theanine's modulation of GABA and glutamate receptors distinguishes its neurological and [antioxidant](/ingredients/condition/antioxidant) profile.

## Health Benefits

• No clinical evidence available - search results lack human trials specific to Gyokuro
• Shading cultivation increases polyphenol content through reduced photodegradation (mechanism study)
• Contains catechins like EGCG and ECG common to green teas (compositional analysis)
• Traditional use focused on flavor/ceremony rather than medicinal applications
• Extraction methods optimize catechin preservation but no health outcomes studied

## Mechanism of Action

EGCG (epigallocatechin gallate) in Gyokuro inhibits COMT, the enzyme responsible for degrading catecholamines like [dopamine](/ingredients/condition/mood) and norepinephrine, potentially extending their signaling duration. L-theanine, present at notably elevated concentrations due to shading (shade inhibits conversion of L-theanine to catechins), acts as a glutamate receptor partial agonist at NMDA and AMPA receptors while also enhancing GABAergic inhibitory tone, contributing to relaxed alertness. Chlorophyll derivatives and ECG (epicatechin gallate) additionally exert antioxidant effects by scavenging [reactive oxygen species](/ingredients/condition/antioxidant) and chelating redox-active metal ions.

## Clinical Summary

No clinical trials have been conducted specifically on Gyokuro as a distinct cultivar; available evidence is extrapolated from broader green tea and isolated EGCG/L-theanine research. Randomized controlled trials on green tea catechins (typically 400–800 mg EGCG/day) have demonstrated modest reductions in [LDL cholesterol](/ingredients/condition/heart-health) and fasting glucose in metabolic syndrome populations, but these doses exceed what a standard serving of Gyokuro provides. L-theanine studies (100–200 mg isolated compound) show statistically significant improvements in alpha-wave EEG activity and self-reported relaxation, though direct translation to brewed Gyokuro is unvalidated. The current evidence base is mechanistic and compositional rather than clinically confirmed, meaning health claims specific to Gyokuro remain preliminary.

## Nutritional Profile

Gyokuro is consumed as a brewed tea infusion; nutritional content reflects both the leaf composition and what is extracted into the cup. Dry leaf composition per 100g: protein 29-34g (notably higher than standard green teas due to shading-induced amino acid accumulation, particularly L-theanine at 2.5-4.5g/100g dry leaf — roughly 2-3x that of standard sencha); total catechins 9-14g/100g dry leaf (lower than sun-grown green teas due to shading reducing photosynthetic polyphenol synthesis), comprising EGCG (epigallocatechin gallate) ~5-8g, ECG (epicatechin gallate) ~1-2g, EGC ~1-2g, EC ~0.5-1g; chlorophyll content elevated at 0.6-1.2g/100g dry leaf (shading increases chloroplast density), contributing deep green color; caffeine 3.5-4.5g/100g dry leaf (among the highest of Japanese green teas, synergistic with L-theanine for modulated alertness). Per 200ml brewed cup (using ~4g leaf at 50-60°C, 90-120 seconds): L-theanine 40-80mg; caffeine 35-50mg; total catechins 60-120mg; vitamin C (ascorbic acid) 5-10mg (heat-sensitive, preserved by low brewing temperature); vitamin K1 (phylloquinone) trace amounts extracted (~5-10mcg); potassium ~30-50mg; manganese ~0.3-0.5mg. Bioavailability notes: Low brewing temperature (50-60°C traditional for Gyokuro) preserves L-theanine and reduces catechin oxidation but extracts fewer total polyphenols than higher-temperature brewing; EGCG bioavailability from brewed tea is generally 1-5% in humans due to intestinal [metabolism](/ingredients/condition/weight-management); L-theanine bioavailability is high (~95%) with rapid CNS penetration; the elevated amino acid-to-catechin ratio distinguishes Gyokuro nutritionally from other green teas.

## Dosage & Preparation

No clinically studied dosage ranges exist for Gyokuro. Traditional brewing uses 1 gram of leaves per 100ml water at 40-60°C, steeped 2-2.5 minutes, with multi-step extractions possible (50°C for 10 min then 80°C) to enrich catechin content. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Gyokuro contains moderate-to-high caffeine (approximately 35–50 mg per 100 mL serving) and should be used cautiously by individuals with cardiac arrhythmias, anxiety disorders, or hypertension. EGCG at supplemental doses (above 800 mg/day) has been associated with hepatotoxicity in case reports, though typical brewed tea consumption is well below this threshold. Green tea catechins may reduce absorption of certain medications including nadolol, warfarin, and non-heme iron supplements due to chelation and P-glycoprotein interactions. Pregnancy safety at normal dietary intake is generally considered acceptable, but high-dose green tea extracts are not recommended during pregnancy due to potential interference with folate [metabolism](/ingredients/condition/weight-management).

## Scientific Research

The research dossier reveals no human clinical trials, RCTs, or meta-analyses specific to Gyokuro have been conducted. All available data pertains to general Camellia sinensis green teas, with no PubMed PMIDs provided for Gyokuro-specific health outcomes.

## Historical & Cultural Context

Gyokuro was developed around 1835 by tea master Yamamoto Yamaki using bamboo and straw shading in Uji and Yamashiro regions. Since its inception, it has been valued primarily for its umami flavor in Japanese tea ceremonies rather than for medicinal purposes in traditional systems like Kampo.

## Synergistic Combinations

Other green tea cultivars, L-theanine, vitamin C, quercetin, EGCG extracts

## Frequently Asked Questions

### How does gyokuro differ from regular green tea in terms of nutrients?

Gyokuro is shaded for 20–30 days before harvest, which suppresses the enzymatic conversion of L-theanine into catechins, resulting in L-theanine levels roughly 3–4 times higher than those in sun-grown sencha. The shading also elevates chlorophyll content, giving gyokuro its deep green color, while total catechin content (including EGCG and ECG) remains high due to reduced photodegradation of polyphenols.

### Does gyokuro have more caffeine than other green teas?

Yes, gyokuro generally contains more caffeine than standard green teas, with estimates ranging from 35–50 mg per 100 mL, compared to approximately 20–30 mg per 100 mL in typical sencha. The shading process stimulates caffeine biosynthesis in the leaf as part of the plant's stress response, and the use of younger, tender leaves (which are naturally higher in caffeine) also contributes to this elevated level.

### Can gyokuro tea help with focus and relaxation at the same time?

The coexistence of caffeine and elevated L-theanine in gyokuro is the basis for its reputation for producing calm alertness. L-theanine modulates glutamate receptor activity and enhances alpha-wave brain activity, counteracting some of caffeine's anxiogenic effects, a synergy confirmed in studies using 100 mg L-theanine combined with 50 mg caffeine. However, no trials have tested brewed gyokuro directly, so this effect is inferred from isolated compound research.

### What is the EGCG content in gyokuro compared to matcha?

Gyokuro and matcha share similar shade-grown cultivation methods, resulting in comparable EGCG profiles, with both containing roughly 50–70 mg EGCG per gram of dry leaf material. However, because matcha involves consuming the entire ground leaf rather than a water infusion, a standard matcha serving delivers significantly more total EGCG (approximately 60–137 mg per serving) than a steeped gyokuro cup, where extraction efficiency caps EGCG delivery at roughly 40–80 mg depending on brew parameters.

### Is gyokuro safe to drink every day?

Daily consumption of gyokuro at 1–3 cups per day is generally considered safe for healthy adults, as the EGCG and caffeine levels in brewed tea are well below doses associated with adverse effects in clinical reports. Individuals sensitive to caffeine, those taking anticoagulants like warfarin, or people with iron-deficiency anemia should moderate intake, since green tea catechins can reduce non-heme iron absorption by up to 25% when consumed with meals.

### What brewing method preserves the most catechins in gyokuro tea?

Steeping gyokuro at lower temperatures (50–70°C / 122–158°F) for 1–2 minutes preserves catechins better than boiling water, which can degrade heat-sensitive compounds like EGCG. Multiple short infusions are traditionally preferred over a single long steep, as this extraction method optimizes catechin retention while minimizing bitterness.

### Why does the shade-growing process affect gyokuro's nutritional profile?

Shading gyokuro plants from direct sunlight increases polyphenol content, including catechins, because reduced photodegradation allows these compounds to accumulate in the leaves. This cultivation technique also boosts chlorophyll and amino acids like L-theanine, which contribute to the tea's distinctive sweet flavor and nutritional density compared to unshaded green teas.

### Is gyokuro more suitable for sensitive individuals than other green tea supplements?

Gyokuro's higher caffeine content (70–140 mg per 8 oz cup) may make it less suitable for caffeine-sensitive individuals or those seeking gentler stimulation. However, its elevated L-theanine levels may provide a smoother caffeine experience with less jitteriness for regular green tea drinkers, though individual tolerance varies.

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