encyclopedia

Green Tea

Scientific Names:     

Camellia sinensis (L.) O. Kuntze (syn. Camellia thea Link. and Thea sinensis L.) [Fam. Theaceae]     

Forms:     

Tea made from the young, dried, and non-fermented leaves of Camellia sinensis     

Traditional Usage:     

– Acute Breathing Disorders
– Antibacterial
– Anti-caries
– Anti-inflammatory
– Antioxidant
– Antiseptic
– Antispasmodic
– Astringent
– Breathing Disorders
– Canker Sores
– Cellular Regeneration
– Cleansing/Detoxification
– Diarrhea
– Digestive Disorders
– Drowsiness
– Emphysema
– Gingivitis
– Indigestion
– Liver Health Maintenance
– Radiation Poisoning
– Skin Disorders
– Stimulant
– Sunburn
– Tooth Decay (prevention)
– Ulcers (Peptic)
– Ultraviolet Radiation (Sun) Protection
– Vascular Disorders     

Overview:     

Green tea, Camellia sinensis (L.) O. Kuntze (syn. Camellia thea Link. and Thea sinensis L. [Fam. Theaceae], also known as Chinese tea, is native to Asia. Green tea is taken from the same plant as black tea, the only difference being that green tea is not fermented during the drying process. Tea was introduced to Europe in the sixteenth century and its use was commonplace by the seventeenth. Green tea generally comes from China and Japan and black tea from India and Africa. Green tea is often recommended for diarrhea and indigestion. It is high in caffeine and tannins and acts as both a stimulant and anti-diarrheic. Green tea has traditionally been recommended for heart health maintenance, chest pain relief, dizziness, hemorrhoids, ulcers, headache, and drowsiness. Dr. James Duke also recommends drinking Chinese tea for liver protection, ultraviolet radiation protection, skin healing, emphysema, sunburn and cankers. Because tea is legally a beverage, German authorities do not recommend it for therapeutic purposes. Recent studies have found that green tea's polyphenol content can prevent dental cavities through significant anti-plaque effect. Several studies have reported green tea to have anti-platelet-aggregation activity and strong antioxidant properties. Epidemiological research suggests that consumption of green tea may decrease the risk of vascular disorders and abnormal growths of many different types. Recently, epigallocatechin gallate (EGCG), a putative chemopreventive agent and a major component of green tea, was reported to inhibit abnormal cell invasion and angiogenesis. A Phase I/II human trial showed a positive response in 71% of patients given green tea as a colorectal chemopreventive agent. The study measured the dose-related effects of a single dose of green tea on the rectal mucosa of normal volunteers and noted a 50% decreased level of PGE2 (associated with abnormal growths) in rectal mucosa within only 4 hours after consumption.

Clinical Study Results:

To evaluate the anti-caries effect of green tea, a group of 150 volunteers were randomly divided into 3 groups: A, B and C with 50 persons in each. People in test groups A and B were given a green tea polyphenol tablet whereas placebo was given to group C (tablets were taken three times daily). After 3 weeks, group A was given placebo and group B continued with polyphenols for 6 weeks. After using polyphenol tablets for 2 weeks, the plaque index of test groups were clearly lower than the control group (P < 0.01). After stopping use of the polyphenol tablet, the effect was still kept for 3 weeks. It can be concluded that polyphenol tablets from Chinese green tea have significant anti-plaque effect and can therefore help to prevent dental cavities.
Active Ingredients:     

Green and black tea leaves contain: methylxanthines – caffeine (theine), up to 4% with smaller amounts of theobromine and theophylline, as well as traces of adenine and xanthine; tannins. Polyphenols: tannins, mainly catechol tannins (10-20%); (-)-epicatechol, 4-gallocatechol, epigallocatechin gallate (EGCG) and other catechol gallates; flavan-3-ols and flavan-3.4-diols, as well as dimeric thea-flavins and oligomeric proanthocyanidins (thearubigenins); phenolic carboxylic acids such as gallic and chlorogenic acids, etc. Flavour substances: alcohols (hex-3-en-1-ol, benzyl alcohol, and 2-phenyl-ethanol, as well as linalool in black tea and geraniol in green tea.); essential oils (monoterpene aldehydes and alcohols); and theanine, the 5-ethylamide of glutamic acid. Other constituents: abundant flavonoids (including the apigenin derivatives isoschaftoside and vicenin-3); triterpenoid saponins; hydroperoxide lyases (anti-oxidant enzymes, and potent inhibitors of lipoxygenase). The accumulation of aluminum in tea leaves and the occasionally high content of fluorine compounds in older leaves are worth noting. Recent studies show that the residual green tea leaves remaining after tea is made are also rich in powerful antioxidants including (ranked according to suppressive activity against hydroperoxide generation): chlorophyll a > lutein > pheophytin a > chlorophyll b > beta-carotene > pheophytin b. [Wichtl and Bisset 1994; and Higashi-Okai K, Yamazaki M, Nagamori H, Okai Y. Identification and antioxidant activity of several pigments from the residual green tea (Camellia sinensis) after hot water extraction. J UOEH. 2001 Dec 1; 23(4): 335-44].

Suggested Amount:     

To make green tea pour boiling water over a teaspoon of tea (1 teaspoon = 2.5 grams), steep for 2-10 minutes, then strain. For use as a stimulant steep for a maximum of 2 minutes and drink several cups per day. For diarrhea, steep for 10 minutes and drink 2-3 cups per day. (Wichtl and Bisset)
Note: When using green tea for prevention of abnormal growths it is important to use Chinese green tea (Camellia sinensis) that has not been decaffeinated because decaffeinated green tea has been shown in studies to lack activity against abnormal cells. Caffeine, itself, has been shown in studies at the Rockefeller Institute of New York to have activity against abnormal growths. Use green teas certified to be low in fluoride whenever possible.

Drug Interactions:     

Green tea may interfere with the absorption of alkaline medications.

Contraindications:     

Green tea is not recommended during pregnancy and lactation or for those with a serious heart condition, kidney disease, overactive thyroid, involuntary movements, nervousness, and anxiety.

Side Effects:     

Green tea may cause stomach irritations in sensitive individuals. Excessive doses can causes insomnia, headache, dizziness, diarrhea, appetite loss, heart palpitations, shaking, spasms, and vomiting. It has been reported that there is a significant correlation between oesophageal cancer and excessive use of teas high in condensed tannins (related more to black tea than green tea).     

References:     

Duke, J. 1997: The Green Pharmacy, The Ultimate Compendium of Natural Remedies from the World's Foremost Authority on Healing and Herbs. Pp. asthma 78-82; canker sores 142; diarrhea 206; emphysema 223-225; antibacterial for tooth decay prevention and gingivitis 265; inflammatory bowel disease and gastrointestinal distress 346; for liver protection and hepatitis 382; astringent and antiseptic for sores and skin healing 488; sunburn treatment and also U.V. protection 503; tooth decay prevention from fluoride 519. Rodale Press.
 
Krahwinkel T, Willershausen B. 2000. The effect of sugar-free green tea chew candies on the degree of inflammation of the gingiva. Eur J Med Res. 2000 Nov 30; 5(11): 463-7.
 
Liu T, Chi Y. [Experimental study on polyphenol anti-plaque effect in humans]. Zhonghua Kou Qiang Yi Xue Za Zhi. 2000 Sep; 35(5): 383-4.
 
Yang CS, Prabhu S, Landau J. Prevention of carcinogenesis by tea polyphenols. Drug Metab Rev. 2001 Aug-Nov; 33(3-4): 237-53.
 
Wichtl M and NG Bisset (eds). 1994. Theae nigrae folium – Black Tea. In Herbal Drugs and Phyto-pharmaceuticals. (English translation by Norman Grainger Bisset). CRC Press, Stuttgart, Pp. 490-492.