Camellia sinensis · Leaf
Green Tea
Studied in peopleTea leaves picked and quickly heated to keep them green have been prized in China and Japan for over a thousand years, and green tea remains one of the world's most loved drinks.
Traditionally used for
- Traditionally drunk to support alertness and clear thinking
- Used in Chinese tradition as a refreshing, cooling beverage
What research says
NCCIH notes that green tea's caffeine supports alertness. Research on other possible benefits is ongoing and results are mixed.
How people use it
- Steep in water just below boiling (about 175°F) for 2–3 minutes
- Matcha whisked into water or milk
- Cold-brewed overnight in the refrigerator
Safety and interactions
- Contains caffeine; limit if pregnant or sensitive
- Concentrated green tea extract supplements have been linked to rare liver injury
- Green tea can reduce blood levels of nadolol and may interact with other medicines
Always talk with your doctor or pharmacist before using green tea as a supplement, especially with prescription medicine, in pregnancy or before surgery.
Sources
Reviewed October 25, 2026. Evidence tier: Studied in people: Human studies summarized by NIH NCCIH suggest a possible benefit for a specific use. How we rank evidence.