How many cups a day is best?

The long-term evidence for heart and blood vessel protection is strongest around 3–5 cups per day of brewed leaf. Two to four is a reasonable, well-tolerated target for most adults. More can push caffeine into sleep-disturbing territory or aggravate anxiety.

Is EGCG supplement better than drinking the tea?

No. The heart and metabolism findings in the research come from drinking the tea itself. High-dose concentrated EGCG extracts (>800 mg/day, especially on an empty stomach) have been linked to rare but real liver injury and aren't recommended as a shortcut to the tea itself.

Will green tea interfere with my iron?

Tannins (plant compounds that give a dry, puckering taste) in tea reduce absorption of non-heme (plant) iron. If you're iron-deficient or eating an iron-rich meal, leave 60–90 minutes between the meal or supplement and your cup. Heme iron from meat is far less affected.

Chapter 1 of 21

Green Tea

The Essentials

Trials pooled together show modest reductions in total and LDL (the harmful type of cholesterol) cholesterol with daily green tea or its extracts.

Long-term studies following people in Japan and China link regular drinking (~3–5 cups/day) with lower heart and blood vessel mortality.

L-theanine + caffeine (roughly 2:1) produces calm, focused alertness — measurable on attention and reaction-time tasks.

Concentrated EGCG extracts (>800 mg/day) carry hepatotoxicity (liver damage) risk. The brewed leaf at cup doses doesn't.