Tea (green / black)
Camellia sinensis
Other names: green tea, black tea, chá (Chinese 茶), chai (Geo.)
Edible plantPhoto credit: AxelBoldt / Wikimedia Commons
Safety information
Safety information
Toxicity: beverage tea generally safe. High-dose green tea catechin EXTRACTS are a well-established cause of clinically apparent liver injury (LiverTox); EFSA: EGCG >=800 mg/day as supplement raises liver-injury risk. Excess caffeine: insomnia, palpitations, anxiety.
Contraindications: pre-existing liver disease (extracts), pregnancy/breastfeeding (limit caffeine), iron-deficiency anemia (tannins reduce non-heme iron absorption), sensitive cardiac/anxiety conditions.
Interactions: reduces non-heme iron absorption; additive with other caffeine/stimulants; may affect anticoagulants (vitamin K content / antiplatelet effects), and several drug metabolism pathways; catechin extracts add hepatotoxic burden with other hepatotoxins.
Pregnancy & breastfeeding: limit caffeine in pregnancy/breastfeeding
Evidence level
Supported by clinical trials in humans.
Preparations
infusion · leaf
Part used: leaf
Traditional use: fatigue, sensation of weakness, alertness
Proposed mechanism: caffeine stimulant; EGCG catechin antioxidant
dry extract · leaf
Part used: leaf
Traditional use: weight control, metabolic supplement claims
Proposed mechanism: high-dose catechins
Associated conditions
Edibility
Edible parts: leaf is brewed as beverage (food use); not eaten raw in quantity
Nutritional notes
polyphenols/catechins (EGCG), caffeine, theanine, fluoride, small minerals
Healing traditions
Sources (3)
- EFSA scientific opinion on green tea catechins (EFSA, 2018)
- EMA: Camelliae sinensis non fermentatum folium (EMA/HMPC)
- Green Tea - LiverTox (NIH NIDDK)