Overview
Green tea comes from Camellia sinensis leaves that are heated shortly after picking (steamed, in the Japanese tradition, or pan-fired, in the Chinese tradition) to halt oxidation, preserving a green color and a grassy, vegetal flavor. Popular styles include sencha (Japan’s most common green tea), gyokuro (shade-grown before harvest, higher in L-theanine), and dragon well/longjing (a pan-fired Chinese classic). Matcha, a stone-ground whole-leaf green tea powder, is covered in more detail on its own page.
Active compounds and evidence
Green tea is rich in catechins, particularly epigallocatechin gallate (EGCG), along with the amino acid L-theanine and roughly 30–50 mg of caffeine per cup. Green tea has one of the larger human evidence bases among teas: cohort studies, several meta-analyses, and some randomized trials link regular consumption with modestly lower cardiovascular disease risk and improvements in blood lipid markers, and green tea catechin extracts have been studied for metabolic and weight-related endpoints, generally with small effects. These are consistent, replicated associations, though — as with most beverage epidemiology — they don’t establish that tea alone drives the outcome, since tea drinkers often differ from non-drinkers in other lifestyle factors.
Safety and contraindications
- Liver caution with concentrated extracts: While brewed green tea itself has an excellent safety record, high-dose green tea extract supplements (not brewed tea) have been linked to rare cases of liver injury; this is a supplement-specific caution, not a reason to avoid drinking the tea.
- Caffeine sensitivity: Caffeine can affect sleep and anxiety in sensitive individuals; count it toward daily caffeine totals.
- Iron absorption: Tannins can reduce absorption of non-heme iron when tea is consumed alongside iron-rich meals.
- Pregnancy: Count green tea’s caffeine toward the recommended pregnancy limit of roughly 200 mg/day.
How it’s typically prepared
Brewed with water below boiling (around 160–175°F) for 1–3 minutes; higher temperatures or longer steeps extract more tannins and produce a bitter, astringent cup.
Sources
- Harvard T.H. Chan School of Public Health — Tea
- NIH National Center for Complementary and Integrative Health — Green Tea
- USDA FoodData Central
Clinically reviewed by Dr. Shilpa Thakur. Last reviewed 2026-07-20. Educational information, not medical advice; consult a qualified clinician about caffeine intake or before using concentrated green tea extract supplements.