Does Green Tea Have Tannins?

Yes, green tea has tannins. They’re part of why a strong cup can leave your mouth feeling dry, and they’re the reason tea comes up in conversations about iron.

What are the tannins in green tea?

A 2020 review of tea taste names tannins, galloylated catechins (the type that includes EGCG) and flavonol glycosides as the main astringent compounds in a cup of tea. Astringency is the dry, puckery feeling you get from a strong cup.

Catechins are the polyphenols most studied in green tea. A review in Molecules says they usually make up 30 to 42% of the dry weight of the solids in brewed green tea. The biggest one is EGCG, which accounts for 50 to 80% of the total catechins.

Black tea changes the picture. The Molecules review says about 75% of the catechins in the leaves are transformed as black tea ferments, forming pigments called theaflavins and thearubigins. So green tea keeps more of its catechins, and black tea has more of the oxidized forms. See how green and black tea differ.

How many tannins does green tea have?

There isn’t one standard number. One 2024 study from Malaysia measured tannins in commercial tea bags and reported these results:

Tea	Tannins (mg tannic acid equivalents per gram)
Green tea	101.75
Black tea	41.37
Rooibos	38.75

Treat that as a single data point. It tested commercial tea bags with one lab method, and the numbers depend on the method used. It does show that tea contains a lot of them, though.

Do tannins make green tea bitter?

They add to the dry, astringent feel. If a cup tastes harsh, a gentler brew may help. Salada suggests 170°F to 180°F water for green tea and says boiling water can make it bitter. Twinings suggests steeping green tea for 2 minutes. We didn’t find a study that measured tannins at different brewing temperatures, so those are the brands’ brewing tips, not a promise about tannin levels.

Do tannins affect iron?

They can. Tea contains polyphenols, and polyphenols can reduce how much “nonheme” iron you absorb. Heme iron, found in meat, fish and poultry, is hardly affected, according to a review of tea and iron. Here is what the studies show:

• Black tea and herb teas: In a human study, drinks with polyphenols cut iron absorption from a bread meal in proportion to their polyphenol content. Black tea cut it by 79 to 94%. Peppermint tea cut it by 84% and chamomile by 47%.
• Green tea extract: In 10 young women, adding a green tea extract to a meal lowered iron absorption from about 12.1% to 8.9%.
• What we didn’t find: a study of brewed green tea with food. Both studies above measured polyphenols as a group, not tannins alone, and the green tea study used an extract.

A review of tea and iron, written by researchers at Unilever, concluded that enough vitamin C or meat in your meals can overcome the effect, even with a lot of tea. For people at risk of low iron, it suggests drinking tea between meals instead of with them. If you have low iron or take iron supplements, ask your healthcare provider about it.

Is it safe to drink?

The National Center for Complementary and Integrative Health reports no safety concerns for green tea as a drink in adults, though it does contain caffeine. The liver injury reported in rare cases was mainly linked to extract tablets and capsules, not brewed tea.

Does herbal tea have tannins?

Possibly. Herbal teas like peppermint and chamomile don’t come from the tea plant, according to Twinings, which is why they’re caffeine free. See whether green tea counts as an herbal tea. The iron study above found that herb teas still contain polyphenols that block iron. In the tannin study, rooibos came in lower than green tea but not at zero. We found no reliable ranking of tannins across herbal teas, so we won’t claim one.

More on what’s in your cup is in our green tea health guides.