Mother Tincture
Mother tincture of Thea sinensis leaf, used in traditional phytotherapeutic practice.
Tincture
Most Consumed Beverage Worldwide After Water
Biological Overview
Camellia sinensis is an evergreen shrub of the Theaceae family that can reach 15 meters in the wild, though cultivation keeps it small to ease harvesting. It is native to eastern Yunnan, China, and northern India. The leaf branches extensively; older leaves are smooth, while young shoots are covered in fine down — the origin of the term "pekoe" (hair, in Chinese) — and are hand-picked above the petiole's narrowing point.
FamilyTheaceae
CaffeineUp to 4%
Catechin Tannins10–20%
Key CompoundEGCG
Botanical Classification
Taxonomy & Identification
- Latin Name
- Camellia sinensis (L.) O. Kuntze
- Synonyms
- Camellia thea Link, Thea sinensis (L.) Kuntze
- Family
- Theaceae
- Common Names
- Green Tea, Tea Plant, Théier
- Parts Used
- Leaf
- Origin
- Eastern Yunnan (China), northern India
Ethnobotany & Traditional Use
History & Tradition
Tea has been known in China for more than 5,000 years. The tea ceremony was born in Japan in the 16th century, and Jesuit missionaries brought tea to France in the 17th century. It is now the most widely consumed beverage in the world after water.
All three major tea types come from the same leaf, differentiated purely by processing. Black tea is made by storing fresh leaves until they wilt, then rolling them; contact between the leaf's juices and enzymes triggers fermentation, during which catechins are converted into phlobaphenes by oxidases and aromatic compounds develop, before the leaves are roasted and dried.
For green tea, fermentation does not take place: enzymes are inactivated by pressurized steam before drying. Oolong tea is semi-fermented, falling between the two.
⚠ Why "Extract," Not "Tea Leaf"
Most documented pharmacological research — and virtually every commercial supplement — uses a standardized dry extract with known EGCG and total catechin content, not loose tea leaf or brewed infusion of unknown potency. This monograph follows that same standardized-extract framing throughout.
The Key Molecule
EGCG — Deep Dive
Epigallocatechin gallate is the most abundant catechin in unfermented green tea leaf, and the compound standardized in nearly every green tea extract supplement.
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DNA & Amino Acid Protection
Catechins protect DNA and amino acids from nitrosative stress, an effect documented preferentially in green tea over fermented forms. [8]
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Cholesterol Reduction
A systematic review and meta-analysis found green tea catechins decrease total and LDL cholesterol. [8]
⏳
Telomere Length
Tea consumption was associated with longer telomere length in elderly Chinese men in an observational study. [11]
⚠ Standardization Matters
EGCG content varies enormously between brewed tea and standardized extract
Most of the antidiabetic, cardiovascular and antioxidant research documented in this monograph used green tea beverage, isolated catechins, or standardized extract with a known EGCG/total-catechin percentage — not black tea, where fermentation converts much of the catechin content into theaflavins and theaflagallines. [8]
Pharmaceutical Preparations
Parts Used & Available Forms
The leaf is the sole part used, available across traditional infusion and standardized extract preparations.
Infusion / Tea Bags
Infusette or single-dose sachet for traditional brewed infusion — the original, non-extract form.
Infusion
Fluid & Dry Extract
Fluid extract and standardized dry extract — the form used in virtually all commercial EGCG capsule supplements.
Dry Extract · Standardized
Phytochemistry
Composition
Documented phytochemistry of the leaf, the sole part with a described composition in the primary source.
Methylxanthines (Bound to Tannins)Caffeine [1] (= theine) up to 4%, theobromine, theophylline, adenine, xanthine
≤4%
Catechin TanninsCondensed tannin fraction of the leaf
10–20%
CatechinsEpicatechin, epicatechin gallate, gallocatechin gallate, epigallocatechin, epigallocatechin gallate (EGCG); yellow theaflavin and red theaflagalline dimers
Present
ProanthocyanidolsDocumented polyphenol fraction
Present
Oolong-Specific Flavan-3-olsOolonghomobisflavanes A and B
Present
Phenolic AcidsGallic acid and chlorogenic acid
Present
FlavonoidsApigenin derivatives (isoschaftoside, vicenin-3), quercetin (quercetol)
Present
Triterpene SaponinsDocumented saponin fraction
Present
L-TheanineAmino acid structurally close to glutamic acid; present in green tea
Present
Essential OilAldehydes and monoterpenols
Trace
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Stimulant Activity
Documented stimulant effect attributed to caffeine content, up to 4% of leaf composition. [1]
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Antioxidant & Anti-aging
Anti-inflammatory, anti-tumor, antioxidant and anti-aging effects documented, particularly for catechin-rich matcha green tea powder. [2][3]
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Matcha Antidepressant Effect
Matcha extract activates dopaminergic D1-receptor function and prefrontal cortex/nucleus accumbens neurons in stress-sensitive mice, an effect dependent on baseline mental state. [4]
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Antimicrobial
Documented activity against Staphylococcus epidermidis, Micrococcus luteus, and methicillin-resistant Staphylococcus aureus via beta-lactamase-producing strains. [5][7]
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Cholesterol-Lowering
A systematic review and meta-analysis found green tea catechins decrease total and LDL cholesterol. [8]
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LDL Oxidation Inhibition
Flavonoids, notably quercetin, inhibit LDL oxidation, a driver of atherogenesis.
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Neuroprotective & Anticholinesterase
Documented neuroprotective activity and acetylcholinesterase-inhibiting effect. [9][10]
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L-Theanine Neuromodulation
Crosses the blood-brain barrier, raises brain GABA, dopamine and serotonin, reduces PMS symptoms, normalizes blood pressure, and tempers caffeine's irritant effects.
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Telomere Length & Longevity
Tea consumption associated with longer telomere length in elderly Chinese men in an observational study. [11]
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Antidiabetic
Multiple randomized controlled trials document improved insulin sensitivity, lower glycated hemoglobin, increased GLUT-IV expression, improved glucose tolerance, and reduced diabetes incidence. [12][16]
⚖️
Metabolic Syndrome & Weight Regulation
Catechin-rich tea combats insulin resistance in overweight patients with metabolic syndrome, affects body fat distribution, and increases thermogenesis. [17]
✨
Anti-collagenase & Anti-elastase
Documented inhibitory activity against collagenase and elastase enzymes. [19]
Clinical Applications
Clinical Indications
Traditional and researched uses, including one indication the primary source itself flags as uncertain.
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General Wellness
Everyday Consumption
- Pleasure beverage: primary traditional use, worldwide.
- Flavonoid intake: a 200 ml cup of tea provides an average of 135 mg flavonoids.
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Metabolic
Diabetes & Weight Management
- Diabetes: recommended based on documented antidiabetic research.
- Obesity: documented researched indication. [20]
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Cancer Prevention (Preclinical)
Animal Research
- Reduced cancerous nodules in rats: considerable reduction over several months of green tea nutrition; monomeric green tea molecules were most active, unlike the polymerized molecules found in fermented black tea.
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Investigational
Flagged Uncertain in Primary Source
- Alzheimer's disease: explicitly marked as uncertain ("?") in the primary source itself — a preliminary, not established, indication. [21]
Pharmacodynamics
Mode of Action
The documented mechanisms behind green tea's flavonoid activity.
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Estrogen Biosynthesis Modulation
Apigenin, a flavonoid found in the leaf, blocks a step in the estrogen biosynthesis pathway.
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Lipoxygenase Inhibition
Isoschaftoside and vicenin-3, both apigenin derivatives, act as lipoxygenase inhibitors.
Clinical Safety
Safety, Interactions & Precautions
Documented interactions and precautions, with particular relevance to concentrated extract products.
Adverse Effects
- Iron absorption inhibition: tea infusion inhibits non-heme iron absorption in humans — about 30% with green tea, 36–61% with black tea, attributed to an insoluble tannin-iron complex forming in the gastrointestinal tract.
Drug Interactions
- CYP3A4 inhibition (concentrated extract): green tea is a potent CYP3A4 inhibitor — more potent than Agaricus, Viscum, or noni juice in comparative testing. The primary source considers clinically relevant interaction risk unlikely for these botanicals generally, but specifically calls out concentrated green tea products, the standardized extract form featured on this page, as the exception. [22]
- Reduced drug absorption: tannins decrease absorption and bioavailability of certain medications, including alkaloids, neuroleptics and antidepressants.
Clinical Disclaimer: This monograph is for educational and professional reference only. It does not constitute medical advice, diagnosis, or treatment guidance. Always consult a qualified healthcare provider before initiating any phytotherapeutic regimen, particularly if you are taking prescription medications, are pregnant, or have existing health conditions.
Common Questions
Frequently Asked Questions
What is green tea extract made from?
Green tea extract is made from the leaves of Camellia sinensis, the same plant used for oolong and black tea. The difference between them comes from fermentation: green tea leaves are not fermented, oolong is semi-fermented, and black tea is fully fermented.
What is EGCG and why does it matter?
EGCG (epigallocatechin gallate) is the most abundant and most studied catechin in green tea, part of the polyphenol family. It is a potent antioxidant and free-radical scavenger, and is present preferentially in unfermented (green) tea rather than fermented black tea, where fermentation converts catechins into other compounds.
What is the difference between green, black, and oolong tea?
All three come from the same plant, Camellia sinensis, and differ by fermentation. Green tea is unfermented, with enzymes inactivated by steam before drying. Oolong is semi-fermented. Black tea is fully fermented: leaves are wilted, rolled, and their catechins are converted into phlobaphenes by oxidases before roasting and drying.
Does green tea extract help with blood sugar or diabetes?
There is meaningful documented evidence: randomized controlled trials found green tea consumption improved insulin resistance and inflammation markers, reduced glycated hemoglobin, increased glucose transporter GLUT-IV expression, improved glucose tolerance, and one large cohort study found reduced type 2 diabetes incidence associated with green tea and caffeine intake.
What is L-theanine and how is it related to green tea?
L-theanine is an amino acid structurally close to glutamic acid, found in green tea. It readily crosses the blood-brain barrier, increases brain levels of GABA, dopamine and serotonin, protects against glutamate-induced neurotoxicity, reduces premenstrual syndrome symptoms, helps normalize blood pressure, and tempers the irritating effects of caffeine.
Can green tea extract interact with medications?
Yes. The tannins in tea reduce the absorption and bioavailability of certain medications, including alkaloids, neuroleptics and antidepressants. Green tea has also been identified as a potent inhibitor of CYP3A4 metabolism, an interaction risk considered most relevant specifically to concentrated green tea extract products rather than ordinary tea drinking.
Does green tea affect iron absorption?
Yes. In humans, tea infusion inhibits the absorption of non-heme iron: by about 30% with green tea and 36 to 61% with black tea, an effect attributed to an insoluble tannin-iron complex that forms in the gastrointestinal tract.
Is green tea linked to longevity?
One study found that Chinese tea consumption was associated with longer telomere length in elderly Chinese men, a marker that researchers have linked to healthy aging, though this is a single observational study rather than definitive proof of a longevity effect.
Primary Literature
Bibliography
↑1. Fujimori N, Ashihara H. Biosynthesis of Caffeine in Flower Buds of Camellia sinensis. Ann Bot. 1993;71(3):279-284. Full Text →
↑2. Kochman J, Jakubczyk K, Antoniewicz J, Mruk H, Janda K. Health Benefits and Chemical Composition of Matcha Green Tea: A Review. Molecules. 2020 Dec 27;26(1):85. PubMed PMID:33375458 →
↑3. Devkota HP, Gaire BP, Hori K, et al. The science of matcha: Bioactive compounds, analytical techniques and biological properties. Trends Food Sci Technol. 2021;118(A):735-743. DOI: 10.1016/j.tifs.2021.10.021 →
↑4. Kurauchi Y, Ohta Y, Matsuda K, et al. Matcha Tea Powder's Antidepressant-like Effect through the Activation of the Dopaminergic System in Mice Is Dependent on Social Isolation Stress. Nutrients. 2023 Jan 22;15(3):581. PubMed PMID:36771286 →
↑5. Hamilton-Miller JM. Antimicrobial properties of tea (Camellia sinensis L.). Antimicrob Agents Chemother. 1995 Nov;39(11):2375-2377. Full Text →
↑6. Sharma A, Gupta S, Sarethy IP, Dang S, Gabrani R. Green tea extract: possible mechanism and antibacterial activity on skin pathogens. Food Chem. 2012 Nov 15;135(2):672-5. PubMed PMID:22868144 →
↑7. Aqil F, Khan MS, Owais M, Ahmad I. Effect of certain bioactive plant extracts on clinical isolates of beta-lactamase producing methicillin resistant Staphylococcus aureus. J Basic Microbiol. 2005;45(2):106-14. PubMed PMID:15812867 →
↑8. Kim A, Chiu A, Barone MK, et al. Green tea catechins decrease total and low-density lipoprotein cholesterol: a systematic review and meta-analysis. J Am Diet Assoc. 2011 Nov;111(11):1720-9. PubMed PMID:22027055 →
↑9. Mandel S, Youdim MB. Catechin polyphenols: neurodegeneration and neuroprotection in neurodegenerative diseases. Free Radic Biol Med. 2004 Aug 1;37(3):304-17. PubMed PMID:15223064 →
↑10. Jazayeri SB, Amanlou A, Ghanadian N, Pasalar P, Amanlou M. A preliminary investigation of anticholinesterase activity of some Iranian medicinal plants commonly used in traditional medicine. DARU J Pharm Sci. 2014;22(1):17. Full Text →
↑11. Chan R, et al. Chinese tea consumption is associated with longer telomere length in elderly Chinese men. Br J Nutr. 2010;103:107-13.
↑12. Fukino Y, Shimbo M, Aoki N, Okubo T, Iso H. Randomized controlled trial for an effect of green tea consumption on insulin resistance and inflammation markers. J Nutr Sci Vitaminol. 2005 Oct;51(5):335-42. PubMed PMID:16392704 →
↑13. Fukino Y, Ikeda A, Maruyama K, Aoki N, Okubo T, Iso H. Randomized controlled trial for an effect of green tea-extract powder supplementation on glucose abnormalities. Eur J Clin Nutr. 2008 Aug;62(8):953-60. PubMed PMID:17554248 →
↑14. Wu LY, Juan CC, Hwang LS, Hsu YP, Ho PH, Ho LT. Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model. Eur J Nutr. 2004 Apr;43(2):116-24. PubMed PMID:15083319 →
↑15. Tsuneki H, Ishizuka M, Terasawa M, Wu JB, Sasaoka T, Kimura I. Effect of green tea on blood glucose levels and serum proteomic patterns in diabetic (db/db) mice and on glucose metabolism in healthy humans. BMC Pharmacol. 2004;4:18. Full Text →
↑16. Iso H, Date C, Wakai K, Fukui M, Tamakoshi A; JACC Study Group. The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among Japanese adults. Ann Intern Med. 2006 Apr 18;144(8):554-62. PubMed PMID:16618952 →
↑17. Cao H, Hininger-Favier I, Kelly MA, et al. Green tea polyphenol extract regulates the expression of genes involved in glucose uptake and insulin signaling in rats fed a high fructose diet. J Agric Food Chem. 2007 Jul 25;55(15):6372-8. PubMed PMID:17616136 →
↑18. Zhou J, Zhang L, Zhang J, Wan X. Aqueous extract of post-fermented tea reverts the hepatic steatosis of hyperlipidemia rat by regulating the lipogenic genes expression and hepatic fatty acid composition. BMC Complement Altern Med. 2014;14:263. Full Text →
↑19. Thring TS, Hili P, Naughton DP. Anti-collagenase, anti-elastase and anti-oxidant activities of extracts from 21 plants. BMC Complement Altern Med. 2009 Aug 4;9:27. PubMed PMID:19653897 →
↑20. Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J. Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine and sympathetic activity. Int J Obes. 2000;24:252-258. Full Text →
↑21. Namita P, Mukesh R, Vijay KJ. Camellia Sinensis (Green Tea): A Review. Glob J Pharmacol. 2012;6(2):52-59. Full Text →
↑22. Engdal S, Nilsen OG. In vitro inhibition of CYP3A4 by herbal remedies frequently used by cancer patients. Phytother Res. 2009 Jul;23(7):906-12. PubMed PMID:19170155 →
Additional Reference Literature
Lehnert M, Lind H, Zhong Z, Schoonhoven R, Marzi I, Lemasters JJ. Polyphenols of Camellia sinensis decrease mortality, hepatic injury and generation of cytokines and reactive oxygen and nitrogen species after hemorrhage/resuscitation in rats. BMC Complement Altern Med. 2010;10:46. Full Text →
Tinahones FJ, Rubio MA, Garrido-Sánchez L, et al. Green tea reduces LDL oxidability and improves vascular function. J Am Coll Nutr. 2008 Apr;27(2):209-13. PubMed PMID:18689551 →
Müller J, Pfaffl MW. Synergetic downregulation of 67 kDa laminin receptor by the green tea (Camellia sinensis) secondary plant compound epigallocatechin gallate: a new gateway in metastasis prevention? BMC Complement Altern Med. 2012;12:258.
Afsana K, Shiga K, Ishizuka S, Hara H. Reducing effect of ingesting tannic acid on the absorption of iron, but not of zinc, copper and manganese by rats. Biosci Biotechnol Biochem. 2004 Mar;68(3):584-92.
Disler PB, Lynch SR, Charlton RW, et al. The effect of tea on iron absorption. Gut. 1975 Mar;16(3):193-200.
Fairweather-Tait SJ, Piper Z, Fatemi SJ, Moore GR. The effect of tea on iron and aluminium metabolism in the rat. Br J Nutr. 1991 Jan;65(1):61-8.
Hamdaoui MH, Chahed A, Ellouze-Chabchoub S, Marouani N, Ben Abid Z, Hédhili A. Effect of green tea decoction on long-term iron, zinc and selenium status of rats. Ann Nutr Metab. 2005 Mar-Apr;49(2):118-24.
Hogenkamp PS, Jerling JC, Hoekstra T, Melse-Boonstra A, MacIntyre UE. Association between consumption of black tea and iron status in adult Africans in the North West Province: the THUSA study. Br J Nutr. 2008 Aug;100(2):430-7.
Sharma NK, Ahirwar D, Jhade D, Jain VK. In vitro anti-obesity assay of alcoholic and aqueous extracts of camellia sinensis leaves. IJPSR. 2012;3(6):1863-1866.