Green Tea
Camellia sinensis
Description
overall appearance
An evergreen shrub or small tree reaching 9–15 m in the wild but maintained at 0.6–1.5 m in cultivation through regular pruning. Has a dense, rounded form with alternating, glossy leaves. In plantation cultivation, plants are kept in low flat rows for easy hand-picking.
roots
Deep taproot extending 1–1.5 m, with dense lateral fibrous roots in the top 30 cm of soil; strongly acidophilic root system with mycorrhizal associations
stem
Woody, multi-branching shrub with smooth gray-brown bark on older stems; young shoots are covered with fine white hairs (pekoe) and are the primary harvest material
leaves
Simple, alternate, elliptic to oblong, 5–10 cm long by 2–4 cm wide; dark green, glossy above, paler and slightly hairy below; margins finely serrate; apex acuminate
flowers
White, fragrant, 2.5–4 cm diameter, with 5–9 petals and prominent yellow stamens; solitary or in small axillary clusters; blooms October through February
fruits/seeds
Woody capsule 2–3 cm diameter, brown, containing 1–3 round seeds 1–1.5 cm diameter; seeds have high oil content (tea seed oil)
Active Compounds
Traditional Uses
- Chinese medicine (TCM) used green tea for over 4,000 years to sharpen mental clarity, reduce fatigue, and aid digestion
- Shen Nong's Bencao Jing (c. 2700 BCE legend) records tea as antidote to poisoning from 72 toxic herbs
- Japanese Zen Buddhist tradition uses matcha in chado (tea ceremony) for meditative focus and spiritual clarity
- Traditional use in China to treat dysentery, diarrhea, and digestive disorders as an antimicrobial agent
- Applied topically in Asian folk medicine for wound healing, sunburn treatment, and skin infections
- Used in Ayurvedic tradition as nervine tonic and for reducing excess pitta (heat) constitution
- Traditional use for detoxification, particularly to counteract effects of alcohol and food poisoning
- Vietnamese and Thai traditional medicine uses strong green tea infusions for headaches and mild pain
Modern Applications
- Cancer prevention: EGCG inhibits tumor angiogenesis and induces apoptosis; epidemiological studies link green tea consumption to reduced rates of breast, prostate, and colorectal cancers
- Cardiovascular protection: meta-analyses of 9+ RCTs show significant reductions in LDL cholesterol and blood pressure
- Cognitive enhancement: L-theanine + caffeine synergy improves attention, working memory, and reaction time vs. caffeine alone
- Type 2 diabetes management: catechins improve insulin sensitivity and reduce postprandial glucose (10+ RCTs)
- Weight management: EGCG increases fat oxidation and thermogenesis; meta-analysis shows 1.3 kg mean weight loss vs. placebo
- Neuroprotection: EGCG reduces amyloid-beta aggregation and tau phosphorylation in Alzheimer's models
- Antiviral activity: EGCG inhibits influenza, HIV, and SARS-CoV-2 spike protein binding in vitro
- Oral health: polyphenols inhibit Streptococcus mutans and reduce dental caries in clinical studies
⚠️ Safety Information
Contraindications
- Pregnancy: limit to 2 cups/day; EGCG interferes with folate metabolism at high doses, linked to neural tube defects
- Severe anemia: tannins and EGCG significantly inhibit non-heme iron absorption; take 2 hours apart from iron supplements
- Liver disease: high-dose extracts (>800 mg EGCG/day) associated with hepatotoxicity; contraindicated with existing hepatic impairment
- Anxiety disorders: caffeine content may exacerbate panic and anxiety symptoms
- Glaucoma: caffeine transiently increases intraocular pressure
Side Effects
- Insomnia and sleep disruption with late-day consumption due to caffeine content
- Gastrointestinal irritation: nausea, stomach upset, and constipation especially with high-dose extracts on empty stomach
- Hepatotoxicity: rare but documented with high-dose EGCG extracts (>800 mg/day); liver enzyme elevation reported
- Reduced iron absorption leading to iron deficiency with chronic very high intake
- Caffeine-related effects: headache, jitteriness, tachycardia at high doses
- Teeth staining with heavy consumption
Drug Interactions
- Anticoagulants (warfarin): vitamin K content and antiplatelet catechins may alter INR; monitor closely
- Iron supplements and iron-rich foods: EGCG chelates non-heme iron; separate dosing by 2+ hours
- Stimulant medications and MAO inhibitors: additive effects; risk of cardiovascular overstimulation
- Bortezomib (cancer chemotherapy): EGCG has been shown to inhibit bortezomib's proteasome-inhibiting activity
- Beta-blockers (atenolol, nadolol): EGCG reduces plasma concentrations of some beta-blockers via P-glycoprotein inhibition
Parts Used
- Young leaves and leaf buds (unoxidized)
- Matcha (whole leaf powder)
- Standardized extract (EGCG)
- Shoot tips (first flush)
Preparation Methods
Brewed green tea: 2–3 g loose leaf in 150 ml water at 70–80°C for 2–3 minutes; 3–5 cups/day (300–400 mg catechins)
Matcha powder: 1–2 g whisked in 70°C water or milk; provides 137 mg EGCG per 1 g serving
Standardized EGCG extract capsules: 400–800 mg/day (standardized to 50% EGCG); higher doses require food co-administration
Green tea tincture (1:5 in 30% ethanol): 3–5 ml three times daily
Topical EGCG cream (0.1–5%): applied twice daily for skin conditions and photoprotection
Green tea mouthwash: 1–2% catechin solution, rinse 30 seconds twice daily for oral health
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