# Camellia sinensis 'Asatsuyu'

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/camellia-sinensis-asatsuyu
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-24
**Evidence Score:** 2 / 10
**Category:** Tea Cultivars
**Also Known As:** Camellia sinensis var. sinensis 'Asatsuyu', Asatsuyu tea, Natural gyokuro cultivar, Japanese green tea 'Asatsuyu', Sencha 'Asatsuyu', Uji cultivar tea

## Overview

Camellia sinensis 'Asatsuyu' is a shade-tolerant Japanese green tea cultivar exceptionally rich in L-theanine and chlorophyll, with one of the highest amino acid profiles among registered cultivars. Its elevated L-theanine content modulates alpha brain wave activity and attenuates caffeine-induced adrenergic stimulation, producing calm alertness without sedation.

## Health Benefits

• No clinical evidence available - research typically focuses on green tea from C. sinensis generally rather than this specific cultivar
• General green tea benefits may apply but are not cultivar-differentiated in available research
• High amino acid content, particularly L-theanine, suggests potential relaxation effects (no cultivar-specific studies)
• Contains polyphenols and catechins typical of green tea (no 'Asatsuyu'-specific concentrations documented)
• No RCTs, meta-analyses, or clinical trials specific to this cultivar were identified

## Mechanism of Action

L-theanine, the dominant bioactive in Asatsuyu, crosses the blood-brain barrier and binds to glutamate receptors (AMPA, NMDA, and kainate subtypes), inhibiting excitatory neurotransmission while simultaneously upregulating GABA synthesis. It also increases brain-derived neurotrophic factor ([BDNF](/ingredients/condition/cognitive)) expression and modulates serotonergic and [dopamine](/ingredients/condition/mood)rgic pathways, contributing to mood stabilization. Catechins such as EGCG (epigallocatechin-3-gallate) inhibit catechol-O-methyltransferase (COMT) and reduce [reactive oxygen species](/ingredients/condition/antioxidant) via Nrf2 pathway activation, though catechin concentrations in Asatsuyu are lower relative to amino acids due to its shade-grown characteristics.

## Clinical Summary

No clinical trials have been conducted specifically on the Asatsuyu cultivar, making cultivar-differentiated evidence unavailable. Research on L-theanine broadly — the compound at which Asatsuyu excels — includes randomized controlled trials (n=18–100) demonstrating 40–50mg doses increase alpha wave amplitude on EEG within 45 minutes and reduce perceived stress scores by 10–15% on validated scales. A 2019 meta-analysis of 13 RCTs found L-theanine combined with caffeine, as naturally present in green tea, improved reaction time and attention accuracy versus caffeine alone. Extrapolation from these findings to Asatsuyu specifically requires caution, as processing method, brew parameters, and cultivar interactions remain unvalidated in isolation.

## Nutritional Profile

Asatsuyu is a shade-tolerant Japanese green tea cultivar with a distinctively elevated amino acid profile compared to standard C. sinensis cultivars. L-theanine content is notably high, estimated at 2.5–4.5% of dry leaf weight, substantially above the 1–2% typical of most green tea cultivars, owing to its natural shade-adapted genetics that mimic shaded cultivation conditions. Total free amino acids reach approximately 4–6% of dry weight. Catechin profile per 100ml brewed tea: epigallocatechin gallate (EGCG) approximately 60–100mg, epigallocatechin (EGC) 20–40mg, epicatechin gallate (ECG) 15–30mg, epicatechin (EC) 10–20mg; total catechins estimated 100–200mg per 100ml, comparatively moderate due to the high amino acid-to-catechin ratio characteristic of this cultivar. Caffeine content approximately 25–40mg per 100ml brewed tea. Chlorophyll content is elevated relative to sun-grown cultivars, estimated 0.6–1.2mg/g dry weight, contributing to the characteristic deep green color. Vitamin C (ascorbic acid) approximately 150–250mg per 100g fresh leaf. Vitamin K1 present at approximately 700–1000mcg per 100g dry leaf. Minerals per 100g dry leaf: potassium approximately 2000–2500mg, calcium 300–500mg, magnesium 150–250mg, manganese 30–60mg, fluoride 1–3mg. Theanine bioavailability from brewed tea is high (>80%) due to its water-soluble nature and absence of significant binding compounds. Catechin bioavailability is moderate (20–40%) and enhanced by acidic conditions; the relatively lower catechin concentration in this cultivar compared to astringent varieties may reduce polyphenol-protein binding in the gut, potentially improving net absorption. Protein content of dry leaf is approximately 15–25% by weight but largely unavailable from brewed tea preparation.

## Dosage & Preparation

No clinically studied dosage ranges are available for 'Asatsuyu'. Traditional consumption follows standard Japanese green tea preparation: 2-3g of dried leaves per 150-200mL water, steeped 1-2 minutes. No standardization for catechins or L-theanine content has been specified for this cultivar. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Asatsuyu, consumed as brewed tea, carries a well-established safety profile consistent with other green teas, with adverse effects generally limited to caffeine-related [insomnia](/ingredients/condition/sleep), anxiety, or tachycardia at high intake volumes exceeding 5–6 cups daily. EGCG at supplemental doses above 800mg/day has been associated with hepatotoxicity in case reports, though brewed tea consumption rarely approaches these levels. L-theanine may potentiate antihypertensive medications by enhancing vasodilatory effects, and caffeine present in the cultivar can interact with stimulant drugs, MAO inhibitors, and anticoagulants such as warfarin. Pregnant individuals should limit green tea intake to under 200mg caffeine daily, and those with iron-deficiency anemia should avoid consuming it with meals due to catechin-mediated inhibition of non-heme iron absorption.

## Scientific Research

No clinical trials, RCTs, or meta-analyses specific to Camellia sinensis 'Asatsuyu' were identified in the research. PubMed PMIDs are unavailable for cultivar-specific studies, as research typically focuses on green tea from C. sinensis generally rather than individual cultivars.

## Historical & Cultural Context

'Asatsuyu' has no documented historical use in traditional medicine systems, as it was registered in 1953 from 1920s Kyoto cuttings, postdating classical Japanese Kampo or Chinese traditions. It has been valued in modern Japanese tea culture since the mid-20th century for sencha and 'natural gyokuro' production, prized for its umami, sweetness, and bright green liquor.

## Synergistic Combinations

L-theanine, EGCG, vitamin C, quercetin, piperine

## Frequently Asked Questions

### What makes Asatsuyu different from other green tea cultivars?

Asatsuyu is a registered Japanese cultivar (registered 1953) distinguished by exceptionally high total amino acid content, particularly L-theanine, which can comprise over 50% of total amino acids due to its shade tolerance reducing photosynthetic conversion of theanine to catechins. This gives it a sweeter, more umami-forward flavor profile and a relatively lower catechin-to-amino-acid ratio compared to sun-grown cultivars like Yabukita. It is primarily used in high-grade gyokuro and matcha production.

### How much L-theanine is in Asatsuyu green tea?

Precise L-theanine content varies by harvest, shading duration, and processing method, but shade-grown cultivars like Asatsuyu can yield 20–45mg of L-theanine per 250ml brewed cup, compared to 8–20mg in typical sun-grown green teas. First-flush (ichibancha) leaves harvested in spring after extended shading periods produce the highest concentrations. Matcha preparations using Asatsuyu leaf would deliver higher per-serving amounts since the whole leaf is consumed.

### Does Asatsuyu green tea help with anxiety or stress?

There are no clinical studies on Asatsuyu specifically for anxiety, but its high L-theanine content is relevant to this question. Multiple RCTs on isolated L-theanine (100–200mg doses) show statistically significant reductions in subjective stress and salivary cortisol in acutely stressed healthy adults, with effects measurable within 30–60 minutes. The caffeine naturally present in Asatsuyu also modifies this effect, with the L-theanine:caffeine ratio in shade-grown teas generally favoring a calmer stimulation compared to coffee.

### Is Asatsuyu green tea safe to drink every day?

Daily consumption of Asatsuyu as brewed green tea is considered safe for healthy adults at moderate intake (2–4 cups per day), consistent with general green tea safety data from large-scale epidemiological studies including the Japanese Ohsaki cohort (n=40,530). Regular consumption at these levels is associated with reduced cardiovascular disease risk in observational data, though Asatsuyu-specific long-term data does not exist. Individuals sensitive to caffeine, those on blood-thinning medications, or those with liver conditions should consult a healthcare provider before high-volume consumption.

### What is the best way to brew Asatsuyu to preserve L-theanine?

L-theanine is water-soluble and extracts efficiently at lower temperatures, making brewing at 60–70°C (140–158°F) for 90–120 seconds the optimal approach for maximizing amino acid extraction while minimizing astringent catechin and caffeine release. Higher temperatures (above 80°C) accelerate catechin extraction, altering the amino acid-to-catechin balance and reducing the cultivar's characteristic sweetness. Using a soft or filtered water source with low mineral content also improves extraction efficiency of polar compounds like L-theanine.

### Is Asatsuyu safe for pregnant or breastfeeding women?

While moderate green tea consumption is generally considered safe during pregnancy, Asatsuyu contains caffeine which crosses the placenta; most health authorities recommend limiting caffeine intake to under 200 mg daily during pregnancy. Breastfeeding women should also be cautious as caffeine passes into breast milk and may affect infant sleep. Consulting with a healthcare provider before regular consumption is advisable for both pregnancy and breastfeeding.

### Can Asatsuyu green tea interact with blood pressure or heart medications?

Asatsuyu contains caffeine and bioactive compounds that may interact with cardiovascular medications, including blood pressure regulators and certain heart condition treatments. The caffeine content could potentially amplify effects of stimulant-based medications or interfere with beta-blockers and other cardiac drugs. Anyone taking prescription medications for heart or blood pressure conditions should consult their healthcare provider before regularly consuming Asatsuyu.

### How does Asatsuyu compare to other premium Japanese green tea cultivars in terms of amino acid content?

Asatsuyu is bred specifically for high L-theanine and amino acid content, positioning it among premium cultivars; however, direct comparative studies measuring amino acids across cultivars are limited in published research. Cultivars like Gyokuro and Kabusecha are also known for elevated amino acid profiles due to shade-growing practices, though Asatsuyu's specific breeding emphasizes these compounds. Actual amino acid levels can vary significantly based on harvest timing, processing methods, and growing conditions rather than cultivar alone.

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