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Green tea (Camellia sinensis)

Synonyms/Common Names/Related Substances:

  • Anthocyanins, árbol del té (Spanish), arbre à thé (French), aromatized green tea infusions, caffeine, čaj (Czech, Russian, Slovenian), čaje zelené (Czech), čajnoe derevo (Russian), čajovník čínský (Czech), camellia, Camellia assamica, Camellia sinensis, Camellia sinensis (L.) Kuntze, camellia tea, Camellia thea, Camellia theifera, catechins, çay (Turkish), cha (Chinese, Thai, Japanese, Korean, Sinhalese, Urdu), chá (Portuguese - Brazil), cha no ki (Japanese), chaa (Hindi), chaay (Hindi, Sinhalese), chá-da-Índia (Portuguese), chaha (Kannada), chai (Hindi, Russian), chainoe derevo (Russian), chá-preto (Brazilian), chay (Persian, Urdu), chaya (Tamil), Chinese rea, Chinesischer Thee (German), chiya (Nepali), EGC, EGCG, epicatechin gallate, epicatechins, epigallocatechin, (-)-epigallocatechin, epigallocatechin-3-gallate, gamma-aminobutyric acid, green tea extract, GTE, herbata chińska (Polish), hiina teepõõsas (Estonian), Hydroxycut®, ichibi (Japanese), Japanese tea, kamelia (Polish), lignin, lotus-f3, L-theanine, matcha, matcha green tea, matsu-cha tea, methylated EGCG, methylxanthine, nok cha (Korean), O-methylated catechin, organic acids, phenolic acids, phytochemicals, pianta del tè (Italian), planta del té (Spanish), Poly E, polyphenols, Polyphenon E®, proanthocyanidins, shay (Arabic), sinecatechins, sinecatechins 15% ointment, te (Danish, Kannada, Norwegian, Sinhalese, Swedish), tannins, té (Spanish), tea (Hungarian), tea green, tea pigment, tebusk (Danish), tebuske (Swedish), tee (Finnish, German), teekameelia (Estonian), teepensas (Finnish), Teestrauch (German), teestruik (Dutch), teh (Hebrew, Malay), teyaku (Telugu), thayilai (Tamil), thé (French), Thea bohea, Thea sinensis, Thea viridis, Theaceae (family), theanine, theesoortt (Dutch), tTheestrauch (German), theestruik (Dutch), théier (French), theifers, theobromine, theophylline, Veregen®, vitamins.
  • Combination product examples: AR25®, Exolise®, FertilityBlend (chasteberry extract, green tea extracts, L-arginine, vitamins and minerals), LGNC-07 (green tea extract and L-theanine), LipoKinetix® (norephedrine, caffeine, yohimbine, diiodothyronine, and sodium usnate), Metabolife 356 (caffeine, plus extracts of green tea, Garcinia cambogia, and yerba mate), Nature's Bounty® Green Tea Extract, PhosphoLEAN™ (85mg of N-oleyl-phosphatidylethanolamine extracted from soya lecithin and 121mg of a dry green tea extract), Puritan's Pride® Green Tea Extract.
  • Note: This monograph focuses on green tea. Green tea contains caffeine. Thus, there may be theoretical uses, safety issues, adverse effects, interactions, and mechanisms of action associated with caffeine that are not specifically addressed in this monograph. For a more complete overview of green tea, information on caffeine is available in the Natural Standard caffeine monograph.

Clinical Bottom Line/Effectiveness

Brief Background:

  • Green tea is made from the dried leaves of Camellia sinensis, a perennial evergreen shrub. Green tea, black tea, and oolong tea are all derived from the same plant. According to secondary sources, green tea is produced by lightly steaming the freshly cut leaf, thus not allowing oxidation of the enzymes within the leaf to take place. Green tea is produced and consumed primarily in China, Japan, and countries in North Africa and the Middle East.
  • Research has shown that plant-derived polyphenolic compounds are promising nutraceuticals for control of various disorders such as cardiovascular, neurological, and neoplastic disease (1). Similar to wine, curcumin, purple sweet potato leaves, and cocoa, green tea is high in polyphenols (catechins, anthocyanins, phenolic acids) (2;3;4;5). Unlike leaves used for black or oolong teas, leaves used to prepare green tea do not undergo a fermentation process. Therefore, green tea retains higher levels of catechins, which are highly antioxidant polyphenolic compounds. Many of the potential cancer-preventive effects of green tea are thought to be mediated by its most abundant catechin, epigallocatechin gallate (EGCG) (6). Tea also contains tannins, trace elements, and vitamins.
  • Green tea is a source of caffeine; one cup of tea contains approximately 50mg of caffeine, depending on the strength and size of the cup (as compared to coffee, which contains 65-175mg of caffeine per cup). For a complete overview of caffeine, information is available in the Natural Standard caffeine monograph.
  • Green tea is used as an antioxidant for chronic disease prevention. It has been studied for genital warts, allergy symptoms, anxiety, arthritis, bone health, cancer, cardiovascular conditions, the common cold, exercise performance, liver disease, prevention of dental caries, diabetes, infections, infertility, human T cell lymphocytic virus, hypercholesterolemia, hypertension, hypertriglyceridemia, liver conditions, menopausal symptoms, mental performance, obesity, photoprotection, skin conditions and healing, and weight loss. Although there is good evidence in support of the use of topical green tea extracts for genital warts, and for green tea constituents for blood lipid lowering, further well-designed clinical trials are required in all areas before further conclusions may be drawn regarding the health benefits of green tea.

Dosing/Toxicology

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Precautions/Contraindications

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Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

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Mechanism of Action

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History

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Evidence Table

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Evidence Discussion

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Products Studied

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Author Information

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.