Green tea 262676 226125292 2008-07-16T22:45:27Z 71.109.111.44 [[Image:Tea leaves steeping in a zhong čaj 05.jpg|right|thumb|250px|Green tea leaves steeping in an uncovered [[gaiwan]]]] {{For|the 2003 Chinese film|Green Tea (film)}}'' '''Green tea '''is made solely with the leaves of'' [[Camellia sinensis]]'', that has undergone minimal [[oxidation]] during processing. Green tea originates from [[China]] and has become associated with many cultures in [[Asia]] from [[Japan]] to the [[Middle East]]. Recently, it has become more widespread in the [[West]], where [[black tea]] is traditionally consumed. Many varieties of green tea have been created in countries where it is grown that can differ substantially due to variable growing conditions, processing and harvesting time. Over the last few decades green tea has begun to be subjected to many scientific and medical studies to determine the extent of its long-purported health benefits, with some evidence suggesting regular green tea drinkers may have lower chances of heart disease and developing certain types of cancer<ref>{{cite web|url=http://www.sciencedaily.com/releases/2003/08/030805072109.htm|title=Green Tea’s Cancer-fighting Allure Becomes More Potent}}</ref>. ==Chinese green teas== [[Image:Maojian.jpg|thumbdXi Hu Longjing.png|thumb|An example of a slightly higher grade of Chinese green tea, called [[Mao Jian tea|Mao Jian]].]] [[Image:Twinings gunpowder green tea.jpg|thumb|A pile of the [[Twinings]] brand [[gunpowder tea]], a variety of Chinese green tea]] ==== Zhejiang Province ==== [[Zhejiang]] is home to the most famous of all teas, Xi Hu Longjing, as well as many other high-quality green teas. ; ''[[Longjing tea|Longjing]]'': The most well-known of [[China Famous Tea|famous Chinese teas]] from [[Hangzhou]], its name in Chinese means ''dragon well''. It is pan-fried and has a distinctive flat appearance. Falsification of Longjing is very common, and most of the tea on the market is in fact produced in [[Sichuan]] Province{{Fact|date=August 2007}} and hence not authentic Longjing. ; ''[[Hui Ming Tea|Hui Ming]]'': Named after a temple in [[Zhejiang]]. ; ''[[Long Ding tea|Long Ding]]'': A tea from [[Kaihua County]] known as ''Dragon Mountain''. ; ''[[Hua Ding tea|Hua Ding]]'': A tea from [[Tiantai County]] and named after a peak in the Tiantai mountain range. ; ''[[Qing Ding tea|Qing Ding]]'': A tea from Tian Mu, also known as ''Green Top''. ;''[[Gunpowder tea|Gunpowder]]'': A popular tea also known as ''zhuchá''. It originated in [[Zhejiang]] but is now grown elsewhere in [[China]]. ==== Jiangsu Province ==== [[Image:Biluochun (medium grade, spring 2007).jpg|thumb|A plate of [[Bi Luo Chun tea]], from Jiangsu Province in China.]] ;''[[Bi Luo Chun tea|Bi Luo Chun]]'': A [[China Famous Tea|Chinese famous tea]] also known as ''Green Snail Spring'', from [[Dong Ting]]. As with [[Longjing]], falsification is common and most of the tea marketed under this name may, in fact, be grown in [[Sichuan]]. ;''[[Rain Flower tea|Rain Flower]]'': A tea from [[Nanjing]]. ;''[[Shui Xi Cui Bo]]'' ==== Hubei Province ==== ; ''[[Yu Lu tea|Yu Lu]]'': A steamed tea known as ''Gyokuro (Jade Dew)'' made in the [[Japanese cuisine|Japanese]] style. ==== Henan Province ==== ;''[[Mao Jian tea|Xin Yang Mao Jian]]'': A [[China Famous Tea|Chinese famous tea]] also known as ''Green Tip,'' or ''Tippy Green.'' ====Jiangxi Province==== ;''[[Chun Mee tea|Chun Mee]]'': Name means "precious [[eyebrows]]"; from [[Jiangxi]], it is now grown elsewhere. ;''[[Gou Gu Nao]]'': A well-known tea within China and recipient of numerous national awards. ;''[[Yun Wu tea|Yun Wu]]'': A tea also known as ''Cloud and Mist''. ====Anhui Province==== [[Anhui]] Province is home to three [[China Famous Tea|Chinese famous teas]]. ;''[[Da Fang tea|Da Fang]]'': A tea from [[Mount Huangshan]] also known as ''Big Square''. ;''[[Mao Feng tea|Huangshan Mao Feng]]'': A [[China Famous Tea|Chinese famous tea]] from [[Mount Huangshan]]. ;''[[Lu An Guapian tea|Lu An Guapian]]'': A [[China Famous Tea|Chinese famous tea]] also known as ''Melon Seed''. ;''[[Hou Kui tea|Hou Kui]]'': A [[China Famous Tea|Chinese famous tea]] also known as ''Monkey tea''. ;''[[Tun Lu tea|Tun Lu]]'': A tea from [[Tunxi District]]. ;''[[Huo Qing tea|Huo Qing]]'': A tea from [[Jing County, Anhui|Jing County]], also known as ''Fire Green''. ; ''[[Hyson]]'': A medium-quality tea from many [[Province (China)|provinces]], an early-harvested tea. ==Japanese green teas== [[Image:Green Tea.jpg|thumb|Japanese green tea]] [[Image:Yamamotoyama Genmaicha.jpg|thumb|''Genmaicha'' green tea]] Green tea ({{lang|jp|緑茶}}; ''ryokucha'') is so ubiquitous in [[Japan]] that it is more commonly known simply as "tea" ({{lang|jp|お茶}}; ''ocha'') and even as "Japanese tea" ({{lang|jp|日本茶}}; ''nihoncha''),although it was first used in China during the [[Song Dynasty]], and brought to Japan by [[Myōan Eisai]], a Japanese Buddhist priest who also introduced the [[Rinzai]] school of [[Zen]] Buddhism. Types of tea are commonly graded depending on the quality and the parts of the plant used as well as how they are processed. There are large variations in both price and quality within these broad categories, and there are many specialty green teas that fall outside this spectrum. The best Japanese green tea is said to be that from the [[Yame]] region of [[Fukuoka Prefecture]] and the [[Uji]] region of [[Kyoto]]. [[Shizuoka Prefecture|Shizuoka Prefecture(静岡県)]] crops 40% of raw tea leaf. ; 玉露 [[Gyokuro]] (''Jade Dew'') :The highest grade Japanese green tea cultivated in special way. Gyokuro's name refers to the pale green color of the infusion. The leaves are grown in the shade before harvest, which alters their flavor. Gyokuro has a high caffeine content (Generally 0.16% in infusion[http://www.mext.go.jp/b_menu/shingi/gijyutu/gijyutu3/toushin/05031802/002/016.pdf]), but the significant [[L-Theanine]] content of Gyokuro slows down and counteracts the caffeine assimilation, and also the amount ingested is very small (Generally 10ml - 60ml). ; 抹茶 [[Matcha]] (''rubbed tea''): A fine ground Ten-cha (碾茶: has very similar cultivation process as Gyokuro) used primarily in the [[tea ceremony]]. Matcha is also a popular [[green tea ice cream|flavor of ice cream]] and other sweets in Japan. ; 煎茶 [[Sencha tea|Sencha]] (''broiled tea''): The first and second flush of green tea, which is the most common green tea in Japan made from leaves that are exposed directly to sunlight. The first flush is also called ''[[shincha|Shin-cha]]'' (新茶: a new tea) ; 玄米茶 [[Genmaicha]] (''Brown-Rice tea''): ''Bancha'' (sometimes Sencha) and roasted ''genmai'' ([[brown rice]]) blend. It is often mixed with a small amount of Matcha to make the colour better. ; 冠茶 [[Kabusecha tea|Kabusecha]] (''covered tea''): ''kabusecha'' is ''sencha'' tea, the leaves of which have grown in the shade prior to harvest, although not for as long as Gyokuro. It has a more delicate flavor than Sencha. ; 番茶 [[Bancha tea|Bancha]] (''common tea''): Sencha harvested as a third or fourth flush tea between summer and autumn. Aki-Bancha (autumn Bancha) is not made from entire leaves, but from the trimmed unnecessary twigs of the tea plant. ; 焙じ茶 [[Hojicha|Hōjicha]] (''pan fried tea''): A strong roasted green tea. ; 茎茶 [[Kukicha tea|Kukicha]] (''stalk tea''): A tea made from stalks produced by harvesting one bud and three leaves. ; 玉緑茶 [[Tamaryokucha]]: A tea that has a tangy, berry-like taste, with a long almondy aftertaste and a deep aroma with tones of citrus, grass, and berries. ; Okinawan Tea ==Other green teas== * [[Ceylon tea (green)|Green Tea from Ceylon]] * [[Kahwah]] ==Brewing== Generally, 2.25 grams of tea per 6 ounces of water, or about one teaspoon of green tea per cup, should be used. With very high quality teas like gyokuro, more than this amount of leaf is used, and the leaf is steeped multiple times for short durations. Green tea brewing time and temperature varies with individual teas. The hottest brewing temperatures are 180°F to 190°F (82°C to 88°C) water and the longest steeping times 2 to 3 minutes. The coolest brewing temperatures are 140°F to 150°F (60°C to 66°C) and the shortest times about 30 seconds. In general, lower quality green teas are steeped hotter and longer, while higher quality teas are steeped cooler and shorter. Tea Masters living in China nowadays say that boiling water must be used all the time even with green teas due to the fact that high quality leaves can handle higher temperatures very well{{Fact|date=June 2008}}. Steeping green tea too hot or too long will result in a bitter, astringent brew for low quality leaves. High quality green teas can be and usually are steeped multiple times; 2 or 3 steepings is typical. The brewing technique also plays a very important role to avoid the tea develop an overcooked taste. If a tea claims to be high grade but the vendor instructions says that boiling water mustn`t be used then there is a chance that the tea is not so high grade. ==Caffeine== Green teas have about a third the [[caffeine]] content, by liquid volume, of coffee.<ref>{{cite web|url=http://www.celestialseasonings.com/products/caffeine.html/authentic-green-tea|title=Celestial Seasonings Caffeine Chart|accessdate=2008-05-22}}</ref> Green teas contain two caffeine metabolites (caffeine-like substances): [[theophylline]], which is stronger than [[caffeine]], and [[theobromine]], which is slightly weaker than caffeine.{{Fact|date=May 2008}} ==Potential effects of green tea on health== {{seealso|Potential effects of tea on health}} ===History=== There is archaeological evidence that suggests that tea has been consumed for almost 5000 years, with China and India being two of the first countries to cultivate it. Green tea has been used as traditional medicine in areas such as India, China, Japan and Thailand to help everything from controlling bleeding and helping heal wounds to regulating body temperature, blood sugar and promoting digestion. The ''Kissa Yojoki'' (''Book of Tea''), written by [[Zen]] priest [[Eisai]] in [[1191]], describes how drinking green tea can have a positive effect on the five vital organs, especially the [[heart]]. The book discusses tea's medicinal qualities, which include easing the effects of [[alcohol]], acting as a [[stimulant]], curing blotchiness, quenching thirst, eliminating indigestion, curing [[beriberi|beriberi disease]], preventing [[fatigue (physical)|fatigue]], and improving [[urinary]] and [[brain]] function. Part One also explains the shapes of tea plants, tea flowers, and tea leaves, and covers how to grow tea plants and process tea leaves. In Part Two, the book discusses the specific dosage and method required for individual physical ailments. ===Unproven claims=== Green tea has been credited with providing a wide variety of health benefits, many of which have not been validated by scientific evidence. These claims and any for which academic citations are currently missing are listed here: * Stopping certain [[neurodegenerative disease]]s such as [[Alzheimer's disease|Alzheimer's]] and [[Parkinson's syndrome|Parkinson's]].<ref>[http://greentealovers.com/greenteahealthotherconditions.htm#brain Green Tea, White Tea: Health Roiboos<!-- Bot generated title -->]</ref> * The prevention and treatment of cancer <ref>[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16785249 The combination of green tea and tamoxifen is effe...[Carcinogenesis. 2006&#93; - PubMed Result<!-- Bot generated title -->]</ref> * Treating [[multiple sclerosis]] <ref>[http://www.annalsnyas.org/cgi/content/abstract/928/1/274 A New Function of Green Tea: Prevention of Lifestyle-related Diseases - Sueoka et al. 928 (1): 274 - Annals of the New York Academy of Sciences<!-- Bot generated title -->]</ref> * Preventing the degradation of [[cell (biology)|cell]] [[cell membrane|membranes]] by neutralizing the spread of [[Radical (chemistry)|free radicals]] which occur during oxidation process. <ref>[http://www.nadraszky.com/fitness/archives/green-tea-health-benefits.html Green Tea Health Benefits<!-- Bot generated title -->]</ref> * Reducing the negative effects of [[LDL|LDL cholesterol]] (bad cholesterol) by lowering levels of triglycerides and increasing the production of [[HDL|HDL cholesterol]] (good cholesterol). * Increasing fat [[oxidation]] (helps the body use fat as an energy source) and raising [[metabolism]]. <ref>[http://www.actabit.com/diet-nutrition/how-effective-is-green-tea-for-weight-loss How effective is green tea for weight loss? | Calorie Counter<!-- Bot generated title -->]</ref> * Joy Bauer, a New York City nutritionist, says [the catechins in green tea] increase levels of the metabolism speeding brain chemical norepinephrine (noradrenaline). * Japanese researchers claim that drinking five cups of green tea a day can burn 70 to 80 extra calories. Dr. [[Nicholas Perricone]], a self-proclaimed anti-aging specialist, appeared on [[The Oprah Winfrey Show]] and told Oprah's viewers they can lose 10 lbs (4.5 kg) in 6 weeks drinking green tea instead of coffee. * Some green tea lovers commonly restrict their intake because of the stimulants it contains &mdash; equivalent to about a third the amount of [[caffeine]] as is found in [[coffee]][http://www.celestialseasonings.com/products/caffeine.html/authentic-green-tea]. Too much caffeine can cause [[nausea]], [[insomnia]], or [[frequent urination]].<ref>[http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Green_Tea.asp?sitearea=ETO ACS :: Green Tea<!-- Bot generated title -->]</ref> ===United States Food and Drug Administration (FDA)=== The article ''Tea: A Story of Serendipity''<ref>[http://www.fda.gov/FDAC/features/296_tea.html Tea: A Story of Serendipity<!-- Bot generated title -->]</ref> appeared in the March 1996 issue of [[FDA]] Consumer Magazine and looked at the potential benefits of green tea. At that time they had not done any reviews of the potential benefits of green tea and were waiting to do it until health claims were filed. They have since denied two petitions to make qualified health claims as to the health benefits of green tea. <ref>[http://www.medterms.com/script/main/art.asp?articlekey=38989 Qualified health claim definition - Medical Dictionary definitions of popular medical terms easily defined on MedTerms<!-- Bot generated title -->]</ref> On June 30, 2005, in response to "Green Tea and Reduced Risk of Cancer Health Claim", they stated: "FDA concludes that there is no credible evidence to support qualified health claims for green tea consumption and a reduced risk of gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, and combined cancers. Thus, FDA is denying these claims. However, FDA concludes that there is very limited credible evidence for qualified health claims specifically for green tea and breast cancer and for green tea and prostate cancer, provided that the qualified claims are appropriately worded so as to not mislead consumers." <ref>[http://www.cfsan.fda.gov/~dms/qhc-gtea.html US FDA/CFSAN - Letter Responding to Health Claim Petition dated January 27, 2004: Green Tea and Reduced Risk of Cancer Health Claim (Docket number 2004Q-0083)<!-- Bot generated title -->]</ref> On May 9, 2006, in response to "Green Tea and Reduced Risk of Cardiovascular Disease", they concluded "there is no credible evidence to support qualified health claims for green tea or green tea extract and a reduction of a number of risk factors associated with CVD." <ref>[http://www.cfsan.fda.gov/~dms/qhcgtea2.html US FDA/CFSAN - Qualified Health Claims: Letter of Denial - Green Tea and Reduced Risk of Cardiovascular Disease (Docket No. 2005Q-0297)<!-- Bot generated title -->]</ref> However in October 2006, the FDA approved an ointment based on green tea. New Drug Application (NDA) number N021902, for kunecatechins ointment 15% (proprietary name Veregen) was approved on October 31, 2006 <ref>[http://www.fda.gov/cder/rdmt/InternetNME06.htm CDER New Molecular Entity (NME) Drug and New Biologic Approvals in Calendar Year 2006<!-- Bot generated title -->]</ref>, and added to the "Prescription Drug Product List" in October 2006. <ref>[http://www.fda.gov/cder/rxotcdpl/pdpl_200610.htm Prescription and Over-the-Counter Drug Product List: 10/2006<!-- Bot generated title -->]</ref> Kunecatechins ointment is indicated for the topical treatment of external genital and perianal warts. <ref>http://www.fda.gov/cder/foi/label/2006/021902lbl.pdf</ref> ===Scientific studies=== According to research reported at the Sixth International Conference on Frontiers in Cancer Prevention, sponsored by the American Association for Cancer Research, a standardized green tea polyphenol preparation (Polyphenon E) limits the growth of colorectal tumors in rats treated with a substance that causes the cancer. "Our findings show that rats fed a diet containing Polyphenon E are less than half as likely to develop colon cancer," Dr. Hang Xiao, from the Ernest Mario School of Pharmacy at Rutgers University, Piscataway, New Jersey, noted in a statement. A [[2006]] study published in the September 13 issue of the [[Journal of the American Medical Association]] concluded "Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer." The study, conducted by the [[Tohoku University]] School of Public Policy in Japan, followed 40,530 Japanese adults, ages 40-79, with no history of [[stroke]], coronary heart disease, or cancer at baseline beginning in [[1994]]. The study followed all participants for up to 11 years for death from all causes and for up to 7 years for death from a specific cause. Participants who consumed 5 or more cups of tea per day had a 16 percent lower risk of all-cause mortality and a 26 percent lower risk of cardiovascular disease than participants who consumed less than one cup of tea per day. The study also states, "If green tea does protect humans against CVD or cancer, it is expected that consumption of this beverage would substantially contribute to the prolonging of life expectancy, given that CVD and cancer are the two leading causes of death worldwide."<ref>[http://jama.ama-assn.org/cgi/content/abstract/296/10/1255 JAMA - Abstract: Green Tea Consumption and Mortality Due to Cardiovascular Disease, Cancer, and All Causes in Japan: The Ohsaki Study, September 13, 2006, Kuriyama et al. 296 (10): 1255<!-- Bot generated title -->]</ref> <ref>http://www.denverpost.com/nationworld/ci_4326770 Article in the Denver Post</ref> A study in the February 2006 edition of the American Journal of Clinical Nutrition concluded "A higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans."<ref>[http://www.ajcn.org/cgi/content/abstract/83/2/355 Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project 1 - Kuriyama et al. 83 (2): 355 - American Journal of Clinical Nutrition<!-- Bot generated title -->]</ref> <ref>[http://www.foodnavigator.com/news/ng.asp?id=66142 Green tea could protect against Alzheimer's<!-- Bot generated title -->]</ref> In May 2006, researchers at [[Yale School of Medicine|Yale University School of Medicine]] weighed in on the issue with a review article that looked at more than 100 studies on the health benefits of green tea. They pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of [[cigarette]] smoking. They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides high levels of [[polyphenol]]s and other [[antioxidant]]s. These compounds may work in several ways to improve cardiovascular health, including preventing blood platelets from sticking together (This [[anticoagulant]] effect is the reason doctors warn surgical patients to avoid green tea prior to procedures that rely on a patient's clotting ability) and improving cholesterol levels, said the researchers, whose study appeared in the May issue of the ''Journal of the American College of Surgeons''. Specifically, green tea may prevent the oxidation of [[LDL cholesterol]] (the "bad" type), which, in turn, can reduce the buildup of plaque in arteries, the researchers wrote.<ref>[http://www.yale.edu/opa/newsr/06-06-01-01.all.html Green Tea and the “Asian Paradox”<!-- Bot generated title -->]</ref> A study published in the August 22, 2006 edition of Biological Psychology looked at the modification of the stress response via [[L-Theanine]], a chemical found in green tea. It "suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation."<ref>[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16930802&query_hl=3&itool=pubmed_docsum L-Theanine reduces psychological and physiological...[Biol Psychol. 2007&#93; - PubMed Result<!-- Bot generated title -->]</ref> In a [[double-blind]], randomized, placebo-controlled trial done by Division of Cardiovascular Medicine, [[Vanderbilt University Medical Center]], Nashville, Tennessee, 240 adults were given either theaflavin-enriched green tea extract in form of 375mg capsule daily or a placebo. After 12 weeks, patients in the tea extract group had significantly less low-density lipoprotein cholesterol (LDL-C) and total cholesterol (16.4% and 11.3% lower than baseline, p<0.01) than the placebo group. The author concluded that theaflavin-enriched green tea extract can be used together with other dietary approaches to reduce LDL-C. A study published in the January, 2005 edition of the American Journal of Clinical Nutrition concluded "Daily consumption of tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity." <ref>[http://www.ajcn.org/cgi/content/abstract/81/1/122 Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men - Nagao et al. 81 (1): 122 - American Journal of Clinical Nutrition<!-- Bot generated title -->]</ref> According to a [[Case Western Reserve University]] School of Medicine study published in the April 13 2005 issue of the [[Proceedings of the National Academy of Sciences]], antioxidants in green tea may prevent and reduce the severity of rheumatoid arthritis. The study examined the effects of green tea polyphenols on collagen-induced arthritis in mice, which is similar to rheumatoid arthritis in humans. In each of three different study groups, the mice given the green tea polyphenols were significantly less likely to develop arthritis. Of the 18 mice that received the green tea, only eight (44 percent) developed arthritis. Among the 18 mice that did not receive the green tea, all but one (94 percent) developed arthritis. In addition, researchers noted that the eight arthritic mice that received the green tea polyphenols developed less severe forms of arthritis. A German study found that an extract of green tea and hot water (filtered), applied externally to the skin for 10 minutes, three times a day could help people with skin damaged from radiation therapy (after 16-22 days). <ref>[http://www.cbsnews.com/stories/2006/12/04/earlyshow/contributors/emilysenay/main2224186.shtml Studies: Green Tea May Help Prolong Life, Senay: Research Also Shows Benefits For Skin, Few Drawbacks - CBS News<!-- Bot generated title -->]</ref> A study published in the December 1999 American Journal of Clinical Nutrition found that "Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both."<ref>[http://www.ajcn.org/cgi/content/abstract/70/6/1040 Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans - Dulloo et al. 70 (6): 1040 - American Journal of Clinical Nutrition<!-- Bot generated title -->]</ref> In lab tests, [[EGCG]], found in green tea, was found to prevent [[HIV]] from attacking T-Cells. However, it is not yet known if this has any effect on humans. <ref>[http://www.webmd.com/content/article/122/114877.htm Green Tea Blocks HIV in Test Tubes<!-- Bot generated title -->]</ref> A study in the August, 2003 issue of a new potential application of Cellular and Molecular Life Sciences found that "a new potential application of (–)-epigallocatechin-3-gallate [a component of green tea] in prevention or treatment of inflammatory processes is suggested" <ref>[http://www.springerlink.com/content/xqa0w01wd87q1nca/ SpringerLink - Journal Article<!-- Bot generated title -->]</ref> However, pharmacological and toxicological evidence does indicate that green tea polyphenols can in fact cause oxidative stress and liver toxicity in vivo at certain concentrations. <ref> [http://pubs.acs.org/cgi-bin/sample.cgi/crtoec/2007/20/i04/html/tx7000515.html] Lambert, J.D., et al., (2007) Possible Controversy over Dietary Polyphenols: Benefits vs Risks, Chem Res Toxicol </ref> This would imply that consumers should exercise caution when consuming herbal products produced from concentrated green tea extract. Other evidence presented in the review cautions against the drinking of green tea by pregnant women. {{Teas}} ==See also== {{Commonscat|Green tea}} * [[Chinese tea culture]] * [[Japanese tea ceremony]] * [[Potential effects of tea on health]] * [[Reactive oxygen species]] * [[Yellow tea]] * [[Korean tea]] * [[White tea]] ==References== <!-- ---------------------------------------------------------- See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for a discussion of different citation methods and how to generate footnotes using the <ref>, </ref> and <reference /> tags ----------------------------------------------------------- --> {{reflist}} ==Literature== * {{cite book | author=Master Lam Kam Cheun et al | year = 2002 | title = The way of tea | publisher = Gaia Books | ISBN 1-85675-143-0 }} ==External links== * [http://www.umm.edu/altmed/ConsHerbs/GreenTeach.html Green Tea (an overview from the University of Maryland Medical Center)] * [http://www.randomhistory.com/1-50/030tea.html A History of Green Tea] [[Category:Chinese tea]] [[Category:Japanese tea]] [[Category:Green tea|*]] [[Category:Dietary antioxidants]] [[ca:Te verd]] [[cs:Zelený čaj]] [[da:Grøn te]] [[de:Grüner Tee]] [[el:Πράσινο τσάι]] [[es:Té verde]] [[eo:Verda teo]] [[fr:Thé vert]] [[gl:Té verde]] [[ko:녹차]] [[hr:Zeleni čaj]] [[id:Teh hijau]] [[it:Tè verde]] [[hu:Zöld tea]] [[nl:Groene thee]] [[ja:緑茶]] [[no:Grønn te]] [[pt:Chá verde]] [[ro:Ceai verde]] [[ru:Зелёный чай]] [[simple:Green tea]] [[sk:Zelený čaj]] [[sh:Zeleni čaj]] [[fi:Vihreä tee]] [[sv:Grönt te]] [[th:ชาเขียว]] [[tr:Yeşil çay]] [[uk:Зелений чай]] [[zh:綠茶]]