The astringency in green tea comes mostly from catechins — a group of polyphenols that also carry most of green tea's studied health properties. When you feel that familiar drying grip at the back of the tongue after a sip of Sencha, that is catechins binding to proteins in your saliva. The same reaction, when you look at it from the other direction, is also what makes catechins so interesting to researchers.
The most abundant and most studied catechin is EGCG (epigallocatechin gallate), which makes up roughly 50–60% of total catechins in green tea. Research on EGCG runs to thousands of peer-reviewed papers, covering antioxidant activity, antimicrobial properties, and cardiovascular markers. What the research shows — and what it does not yet show — is worth understanding alongside the flavor.
The four main catechins in green tea
Catechins are not a single compound. They are a family of four related polyphenols, each with a slightly different chemical structure and a slightly different role in the cup.
| Catechin (abbreviation) | % of total catechins | Key characteristic |
|---|---|---|
| Epigallocatechin gallate (EGCG) | ~50–60% | Most abundant; most studied antioxidant |
| Epigallocatechin (EGC) | ~20% | Second most abundant; antioxidant and antimicrobial research |
| Epicatechin gallate (ECG) | ~10–15% | Moderate astringency contribution |
| Epicatechin (EC) | ~5–10% | Mild; cardiovascular research focus |
Source: Cabrera et al. 2006, Journal of the American College of Nutrition
EGCG dominates — and when people refer to "the antioxidant in green tea," they usually mean EGCG specifically. The gallate esters (EGCG and ECG) are responsible for most of the astringency. Non-gallate forms (EGC and EC) are milder. All four belong to the broader flavonoid family.
One thing all four share: they are unstable under oxidation. When tea leaves wilt and oxidize during processing — the step that turns green tea into oolong or black tea — catechins polymerize into theaflavins and thearubigins. Those new compounds create the deep amber color and the different, more mellow astringency of black tea. The free catechins largely disappear in the process. For catechin content, green tea is the clear winner by tea type.
What the research suggests about EGCG
EGCG has been the subject of extensive research — more than almost any other plant compound. The findings are genuinely interesting, though the gap between laboratory results and what a cup of tea actually delivers to the body is real and worth keeping in mind.
Antioxidant activity: EGCG shows strong antioxidant capacity in laboratory conditions — it donates electrons to neutralize free radicals efficiently. Early studies suggested its antioxidant potency was significantly higher than vitamin C or E. Whether drinking tea produces meaningful antioxidant effects in the human body is a separate question, and the evidence is still developing (Higdon & Frei, 2003). For a broader look at how tea antioxidants work and how they compare across tea types, see our guide to green tea antioxidants.
Cardiovascular markers: Some epidemiological studies associate regular green tea consumption with lower LDL cholesterol levels. A 2011 meta-analysis by Zheng et al. found modest reductions in LDL across multiple studies. The effects at typical tea-drinking levels are real but not dramatic.
Antimicrobial activity: EGCG shows activity against certain bacteria and viruses in laboratory settings. Research in Japan has studied gargling with green tea for cold prevention, with some positive findings. Laboratory conditions and the complexity of the human immune system are different environments, so these findings come with appropriate hedging.
Bioavailability: This is the part that complicates the picture. EGCG is poorly absorbed — only about 2–5% reaches the bloodstream after ingestion. Research doses in studies are typically much higher than what a cup of tea delivers. This does not make tea worthless, but it does mean direct extrapolation from high-dose laboratory results to everyday tea drinking is not straightforward.
The research suggests catechins are doing something useful. The specific mechanisms and the doses required to see clinical effects in humans are still being clarified. For a broader look at what regular tea consumption is associated with, our guide to green tea benefits covers the epidemiological picture.
How brewing affects catechin extraction and flavor
Catechins are heat-soluble. Higher water temperatures pull more of them into the cup — which means more antioxidants, but also more astringency. Lower temperatures favor theanine (the amino acid behind umami and sweetness) over catechins. This is the fundamental flavor tradeoff in brewing green tea.
The practical implications:
- Sencha brewed at 80–90°C will be brisk and astringent — high catechin extraction
- Sencha brewed at 60–70°C will be sweeter and more umami-forward — lower catechin extraction, higher theanine ratio
- Cold-brewed tea extracts almost no catechins — predominantly theanine and flavor compounds
- Longer steeping increases catechin extraction alongside astringency
Second and third flush teas (summer and autumn harvests) also carry more catechins than first flush spring teas. The reason: catechins are partly a stress response in the plant. Longer summer daylight, higher temperatures, and the cumulative sun exposure of a later harvest all push catechin production up. First flush is prized for its theanine-rich sweetness; later flushes lean astringent and brisk.
Brewing temperature is the variable most within your control. Our guide to tea and brewing temperature walks through how temperature affects each tea type.
Common questions about catechins
What is the difference between catechins and EGCG?
EGCG is one member of the catechin family — the most abundant and most studied. When someone says "catechins in green tea," EGCG is doing most of the work numerically. The other three (EGC, ECG, EC) are present alongside it but in smaller quantities and with less research attention.
Does Matcha have more catechins than Sencha?
Not necessarily more catechins per gram of leaf — Matcha is shade-grown, which reduces catechin synthesis compared to sun-grown Sencha. But because you consume the whole powdered leaf when you drink Matcha rather than discarding the used leaves, you take in all the catechins present. A bowl of Matcha delivers more catechins than an equivalent volume of brewed Sencha, even if the Sencha leaf is richer per gram. Our overview of green tea ingredients covers this alongside theanine and caffeine.
Do catechins survive digestion?
Partially. As noted above, EGCG absorption in the gut is relatively low — around 2–5% reaches the bloodstream. Some catechins are metabolized by gut bacteria into other compounds. Research is ongoing into whether these metabolites carry their own effects. What reaches the bloodstream is modest compared to the concentration in the cup.
Catechins are also connected to the broader chemistry of theanine and caffeine in the cup — the three interact both in the plant and in how the body processes them.
If you want to experience catechin-rich tea at home, sun-grown Sencha is the most direct route — and our tea leaf collection includes several options from different harvests and growing regions.
The health-related information summarized here published research and is provided for educational purposes only. It is not medical advice. If you have specific health concerns, please consult a qualified healthcare professional.
References
- Cabrera, C., Artacho, R., & Giménez, R. (2006). Beneficial effects of green tea — a review. Journal of the American College of Nutrition, 25(2), 79–99. PubMed: 16582024
- Higdon, J. V., & Frei, B. (2003). Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions. Critical Reviews in Food Science and Nutrition, 43(1), 89–143. PubMed: 12587987
- Zheng, X. X., Xu, Y. L., Li, S. H., Liu, X. X., Hui, R., & Huang, X. H. (2011). Green tea intake lowers fasting serum total and LDL cholesterol in adults. American Journal of Clinical Nutrition, 94(2), 601–610. PubMed: 21715508
- Manach, C., Scalbert, A., Morand, C., Rémésy, C., & Jiménez, L. (2004). Polyphenols: food sources and bioavailability. American Journal of Clinical Nutrition, 79(5), 727–747. PubMed: 15113710
- National Institutes of Health, Office of Dietary Supplements. (2022). Green Tea Fact Sheet for Health Professionals. NIH ODS: Green Tea