Green Tea & Black camellia sinensis, the Chinese encyclopedia of teas lists 138 distinct green varieties, of which there are more than 12,500 subgroups! Green is unfermented, Black being fermented and semi-fermented would be Oolong. research articles and links online at www.HappyHerbalist.com 

Drinking Green Tea Reduces the Effects of Cigarette Smoking …. May Prevent Oral Cancer … May Prevent Rheumatoid Arthritis … is anti-inflammatory reduces pain, swelling, stiffness, and loss of joint function … prevent tooth decay, works better than the antibiotic tetracycline …

contains polyphenols, + catechins, which protect your heart by lowering cholesterol and improving lipid metabolism, scavengs for free radicals that damage cells, have antibacterial effects and a source of "Epigallocatechin Gallate" (EGCG) which inhibits cancer and lowers the cholesterol levels.

keeps people who have had heart attacks alive, [Harvard Medical School].

[Japanese study] 6,000 women, who drank over 5 cups of GREEN tea per day cut their risk of strokes by 50 percent… Men who drank more than 4.7 cups of BLACK tea a day had a 69 percent reduced risk of stroke and other coronary disease as well s reducing pancreatic cancer [Dutch Study]

Please note that "White Tea"  is considered the healthiest of all the teas and "White Tea" is a green or unfermented tea.

Affects of Regular Tea drinking (not kombucha brewed or flavored teas)

DRINKING GREEN TEA MAY AID IN WEIGHT LOSS 

Two studies were researched to propose that drinking green tea might aid in weight loss. The first study compared the metabolic effect of green tea, in extract, to that of a placebo. The second study, researched by the University of Geneva, investigated the outcome of the combination of  caffeine and a compound called epigallocatechin (EGCG), which is a  catechin, found in green tea. 

In the first study, researchers found that green tea drinkers burned an  additional 70 calories a day. It is believed that the difference is  caused by metabolism enhancing antioxidants, also known as catechins.  These metabolism-enhancing catechins are found in green tea. In the  second study, researchers discovered that the combination of caffeine  and epigallocatechin (EGCG) could enhance metabolic rate by 4%. 


GREEN TEA MAY PREVENT SUN-INDUCED SKIN DAMAGE 

In a case study researched at Case Western Reserve University in  Cleveland, OH, it was found that green tea extracts are also beneficial if they are applied to the skin. Today, an escalating amount of 
skin-care products are beginning to contain green tea extracts.  To obtain this benefit, at least 4 cups of green tea need to be drank a  day. Note that weaker iced-tea is not effective in receiving this benefit. 

We can think of green tea as a supplement for sunscreen, not as a substitute for it. 



HEART ATTACK SURVIVAL RATES AND CONSUMPTION OF TEA 

Researchers at Beth Israel Deaconess Medical Center in Boston, MA  performed a study to demonstrate that tea consumption, both black and  green tea can extend years of life after a heart attack.  In this study, 1,900 heart attack survival victims, including both men  and women in their 60s, were asked tea consumption questions.  Among the 1,900 individuals who had suffered heart attacks, it was found  that heavy tea drinkers who drank 19 or more cups a week reduced their  risks of dying over the next 3-4 years by 44% compared to that of non-tea drinkers. 
Moderate drinkers who drank less than 14 cups a week reduced their risks  by 28% compared to non-tea drinkers. 


TEA MAY STRENGTHEN BONES 

In a study, executed by researchers from National Cheng Kung University Hospital in Tainan, Taiwan, it had been suggested that drinking tea  might strengthen bones. Tea contains fluoride and flavanoids, both of  which may enhance bone strength. 

This study was based on 1,037 men and women, 30 and older, which were  questioned about tea consumption habits and had bone-mineral density  tests. 

It was found that the benefits were most noticeable in people who drank  at least 2 cups of tea a day for at least 6 years. The highest overall  bone-mineral density test was found in people who had consumed tea  habitually for more than 10 years; their bone mineral density test was  6.2% higher than in non-habitual tea drinkers. Habitual tea drinkers for  6-10 years had bone mineral density tests that were 2.3% higher than  non-habitual tea drinkers. No significant differences between tea 
drinkers of 1-5 years and non-habitual tea drinkers were established. 


DRINKING GREEN TEA REDUCES THE EFFECTS OF CIGARETTE SMOKING 

In two different studies, one by scientists at the Academy of Preventive Medicine in Beijing, China and the other by James Klaunig at the Indiana University School of Medicine in Indianapolis, the effects of green tea  on oxidative stress, brought on by the toxins of cigarette smoke, were  investigated. Oxidative stress, an imbalance in the  pro-oxidant/antioxidant status of a cell, appears to cause or 
participate in the development of certain diseases-notably cancer. 

Researches found that when cigarette users drank an equivalent of six cups of green tea a day, their bodies suffered 40% to 50% less oxidative  damage. This potentially lowers their risk of cancer, emphysema, heart  disease and other illnesses. Oxidative damage was reduced to that of levels found in nonsmokers prior to drinking green tea. However, it is important to note that those who drink green tea and continue to smoke are still raising their risk of experiencing oxidative damage.  Nonsmokers who were studied exhibited significant decreases in oxidative damage as well. 



GREEN TEA MAY PREVENT ORAL CANCER 

At a symposium in Washington DC, 1998, a team of Chinese scientists, Ning Li from the Institute of Nutrition and Food Hygiene, Zheng Sun from the Chinese Academy of Preventive Medicine and Junshi Chen from the Beijing Dental Hospital, revealed that drinking green tea improves pre-cancerous conditions of oral leukoplakia in patients and suggests it may have certain preventive effects in oral cancer. 

The study involved 32 patients, 20 males and 12 females, 23-28 years of age with oral mucosa leukoplakia, a pre-cancerous lesion of oral cancer. During a six month period, patients drank three cups of green tea a day and applied a mixture of green tea and glycerin directly to the lesion. As a result, 38% of the patients experienced a reduction in the size of a single lesion or in the total size of multiple lesion by 30% or more. 59% saw no changes at all. At the same time, the frequency and rate of formation of cancerous cells decreased significantly. 

Although the sample size and the time of treatment of this study are limited, the results provide encouraging and direct evidence on the preventive effects of green tea on human cancer. 



GREEN TEA MAY PREVENT RHEUMATOID ARTHRITIS 

Medical researchers at Case Western Reserve University in Cleveland, published a study in April, 1999 reporting that drinking four or more cups of green tea a day may prevent rheumatoid arthritis and reduce the severity of it in those who are currently battling the disease. 

The study was conducted on mice with collagen induced arthritis, which is similar to that of rheumatoid arthritis in humans. The mice that received green tea were less likely to develop arthritis than the mice who received plain drinking water. However, the mice that received green tea and yet still developed arthritis had less severe forms of arthritis. 

It was concluded that the antioxidants present in green tea possess not only cancer-preventeing properties but also anti-inflammatory properties. Rheumatoid arthritis is an inflammatory disease that causes pain, swelling, stiffness, and loss of function in the joints. The  antioxidants in green tea may prevent or reduce the severity of these  symptoms. 

Although further research is needed in this area, the study closely mimics the human disease of Rheumatoid arthritis and provides encouraging evidence on the preventive effects of green tea on 
Rheumatoid arthritis. 


GREEN TEA AS CANCER PREVENTIVE 

Continuing research on the beneficial properties of green tea to human health has produced several new findings. Most notable is a study by Japanese scientists of the Saitama Cancer Research Institute relating the delay of cancer onset with the consumption of green tea. The study  shows that early stage breast cancer spreads less rapidly in women with  a history of drinking five or more cups of green tea a day. As a result,  there is a lower recurrence rate and a longer disease-free period. 

With the evidence that green tea and EGCG, a catechin found only in green tea, are a natural and readily available inhibitor of TNF-, a gene expression which promotes the growth in cancer cells and in their surrounding tissue, it is possible for researchers to extend this idea to other various human diseases. Since EGCG has also been proven to kill cultured cancer cells without causing harm to surrounding healthy cells, green tea could be beneficial not only for cancer prevention but also in 
the therapy and prevention of other diseases. 


STRONGEST OF ALL ANTIOXIDANTS FOUND IN GREEN TEA 

In September, 1997 a study by Dr. Lester Mitscher, professor of  medicinal chemistry at the University of Kansas concluded that green tea contains the strongest of any known form of antioxidants. 

The study found that a cathechin in green tea, epigallocathechin gallate (EGCG), was more than 100 times as effective at neutralizing free radicals as vitamin C, and 25 times more powerful than vitamin E. Both are well known antioxidants. EGCG also topped other antioxidants, such as BHA, BHT, and Resveratol. Antioxidants are thought to prevent cellular damage that leads to certain diseases - especially cancer. 

Mitscher indicated that green tea contained, by far, the highest concentrations of active EGCG. He also stated that the daily consumption of green tea needed for antioxidant effect has not been established, but pointed to previous studies in China and Japan, where people customarily  drink four (or more) cups per day. It has not been determined whether one cup per day is sufficient. 



GREEN TEA CATECHIN COULD INHIBIT TUMOR GROWTH 

In June of this year, Dr. Jerzy Jankun and associates from the Medical College of Ohio published a study in the science journal Nature that offered a possible explanation as to how green tea may work to prevent  certain cancers. 

The group demonstrated that one of the major ingredients in green tea, a catechin known as epigallocathechin -3 gallate (EGCG) acts as a good inhibitor of urokinase, an enzyme crucial for cancer growth. Further,  green tea was compared to a well known urokinase inhibitor called amiloride which can be consumed in a maximum dose of 20 mg per day,  whereas a single cup of green tea contains up to 150mg of EGCG. Green tea lovers who consume five or more cups per day are benefiting from very high levels of inhibitor. Previous studies have concluded that  inhibition of urokinase can decrease or even cause complete remission of cancers in mice. 

The catechin EGCG is not present in black tea as it is destroyed during the fermentation (oxidation) process of tea manufacture. Herbal teas,  which are not derived from the camellia sinensis plant, also do not  contain any levels of EGCG. 

Green tea may inhibit cancer formation in a number of different ways. More research is much needed in this area so that we can gain a better understanding of green teas role in cancer prevention. 



GREEN TEA TEST TO BEGIN 

Cancer researchers in Texas have won approval from federal regulators to  launch the first human trial studies of green tea as a cancer fighting  agent in the United States. Doctors at the University of Texas M.D.  Anderson Cancer Center, along with colleagues at the Sloan-Kettering  Cancer Center in New York will give doses of green tea to patients whose cancer tumors have been diagnosed as untreatable. 

Numerous lab studies have concluded that green tea inhibits tumor growth and metastases. The new research effort will enable physicians to determine whether green tea actually inhibits the formation and growth of cancerous cells in human patients. 

The doses of green tea to be given will be rich in both epigallocathechin (EGC) and epigallocathechin -3 gallate (EGCG). Both seem to be active against human cancer cells. 



GREEN TEA DRINKING MAY REDUCE HEART DISEASE 

In a study presented at the International Symposium on Physiological and  Pharmacological Effects of tea in 1991, researchers from the National Defense Medical College in Saitama, Japan revealed that total serum  cholesterol levels were reduced in Japanese men who were heavy green tea  drinkers. The study involved 1,306 men aged 49 and 56 years old.  A similar study released released in March, 1995 by the Saitama Cancer  Center in Japan, which studied 1,371 men over forty, came to the same  conclusions. Lowering blood cholesterol is associated with preventing heart disease. 


GREEN TEA MAY PROTECT AGAINST ESOPHAGEAL CANCER
Research reported in the June, 1994 issue of the Journal of the National  Cancer Institute, found that Chinese men and women who drink green tea  enjoy a reduced risk of developing esophageal cancer. Green tea is  consumed to a much greater extent in China and other parts of Asia.  Researchers from the National Cancer Institute and the Shanghai (China) 
Cancer Institute interviewed nine hundred esophageal cancer patients and 1,500 without the disease. Subjects who drank green tea and avoided burning hot fluids had significantly lower cancer risk. 


GREEN TEA COMPONENTS - POLYPHENOLS AND CATECHINS 

Most researchers believe that it is the polyphenols in green tea that  are responsible for the health benefits. More specifically, certain  catechins found in tea are believed to be the most powerful. The  catechins in green tea make up a large percentage of the total amount of  polyphenols. Certain catechins, especially epigallocatechin gallate  (EGCG) are believed to provide the most protection. While the level of polyphenols and catechins in green tea can vary, depending on growing conditions, quality of the leaf, and brewing  methods, the following approximates the amount in a cup of green tea. 
The percentages are measured in weight % of extract solids of a green tea beverage. 

Composition of a Green tea Beverage  
Total Polyphenols - 37-56% of green tea solids. 
Total Catechins - 30-42% of green tea solids 
Main Catechin EGCG - 10-13% of green tea solids 

Source: Preventative Medicine (journal of the American Health Foundation) - Volume 21, Number 3, May 1992 

Green Tea Extract - March 10, 1995

Inhibition of mammary gland carcinogenesis by green tea catechins and other naturally occurring antioxidants in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene.

Effects of the naturally occurring antioxidants on mammary gland carcinogenesis were examined in female Sprague-Dawley rats pretreated with 7,12-dimethylbenz[alpha]anthracene (DMBA). Groups of 15-16 7-week-old rats received a 50 mg/kg body weight intra-gastric dose of DMBA, and starting one week thereafter placed on diet containing 0.4% catechol, 1.0% gamma-oryzanol, 2.0% phytic acid, 1.0% green tea catechins (GTC), 1.0% tannic acid or basal diet alone for 35 weeks. Although the final incidences and multiplicities of mammary tumors were not significantly different between DMBA-treated groups, the numbers of survivors in the antioxidant-treated groups at the end of the experiment at week 36 were significantly higher than in the basal diet group. In particular, the survival rate of the GTC group at 93.8% strongly contrasted with that of only 33.3% for rats on the basal diet. At the end of week 18, when all the animals were still alive, the average size of palpable mammary tumors was significantly smaller in the catechol, phytic acid and catechins groups. These results indicate that antioxidants, and GTC in particular, inhibit rat mammary gland carcinogenesis after DMBA initiation.Hirose M, Hoshiya T, Akagi K, et al. Inhibition of mammary gland carcinogenesis by green tea catechins and other naturally occurring antioxidants in female Sprague-Dawley rats pretreated with 7,12 dimethylbenz[alpha]anthracene. Cancer Lett 83:149-156; 1994.

Scavenging action of green tea extracts on singlet oxygen and preventive effect on lipid peroxidation

Singlet oxygen (1O2) produced by illuminated photosensitizer Rose Bengal was detected by its bleaching effect on N,N-dimethylnitrosoaniline(DMNA). The 1O2 could be scavenged by green tea extracts (GTE), with the scavenging action being obvious at the early stage of photosensitized oxidation. The higher the concentration of GTE in the photooxidation reaction system, the stronger the 1O2 scavenging action. The scavenging effect of the fresh GTE solution on singlet oxygen was better than that of old solution. The preventive effects of GTE on lipid peroxidation induced by 1O2 in ghosts and microsomal membranes were also observed. Malondialdehyde (MDA) production was found to be completely inhibited by a high concentration of GTE in the reaction system.Wu Y. [Scavenging action of green tea extracts on singlet oxygen and preventive effect on lipid peroxidation] Chung Kuo I Hsueh Ko Hsueh Yuan Hsueh Pao 15:354-359; 1993.

Inhibitory effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on ultraviolet B light-induced skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated SKH-1 mice.

In a previous study (Z. Y. Wang et al., Cancer Res., 52: 1162-1170, 1992), we found that administration of a water extract of green tea leaves as the sole source of drinking fluid inhibited ultraviolet B light (UVB)-induced carcinogenesis in SKH-1 mice previously initiated with 7,12-dimethylbenz[a]anthracene (DMBA). In the present study, we compared the effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice. A 1.25% water extract of each kind of tea leaf (1.25 g tea leaf/100 ml water) was prepared by passing 4 liters of hot water through 50 g of tea leaves in a Bunn tea brewing machine. The mean concentrations of solids in multiple samples of 1.25% black tea, green tea, decaffeinated black tea, and decaffeinated green tea analyzed during the course of this study were 4.23, 3.94, 3.66, and 3.53 mg/ml, respectively. These concentrations of tea solids are similar to those present in tea brews ingested by humans. Female SKH-1 mice were treated topically with 200 nmol of DMBA, followed 3 weeks later by irradiation with 30 mJ/cm2 of UVB twice weekly for 31 weeks. UVB-induced formation of skin tumors was markedly inhibited by oral administration of 0.63 or 1.25% black tea, green tea, decaffeinated black tea, or decaffeinated green tea as the sole source of drinking fluid 2 weeks prior to and during 31 weeks of UVB treatment. Administration of each of the eight tea preparations not only inhibited the number of tumors, but tumor size was also markedly decreased. Histopathological examination of each tumor showed that oral administration of the eight tea preparations had a marked inhibitory effect on the formation of UVB-induced keratoacanthomas and carcinomas. Administration of 1.25% black tea, green tea, decaffeinated black tea, or decaffeinated green tea inhibited the number of keratoacanthomas per mouse by 79, 78, 73, or 70%, respectively, and the number of carcinomas per mouse was inhibited by 93, 88, 77, or 72%, respectively. In summary, administration of black tea was comparable to green tea as an inhibitor of UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice. Oral administration of decaffeinated black tea or decaffeinated green tea also had a marked inhibitory effect on UVB-induced skin carcinogenesis in DMBA-initiated SKH-1 mice, but these tea preparations were slightly less effective than the regular teas at the high dose level.Wang ZY, Huang MT, Lou YR, et al. Inhibitory effects of black tea, green tea, decaffeinated black tea, and decaffeinated green tea on ultraviolet B light-induced skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated SKH-1 mice. Cancer Res 54:3428-3435; 1994.

A potent thromboxane formation inhibitor in green tea leaves.

A ninhydrin positive compound (L2) now identified as 2-amino-5-(N-ethylcarboxyamido)-pentanoic acid, from unprocessed tea leaves was a potent inhibitor of thrombin-stimulated thromboxane formation in rabbit whole blood (Ali and Afzal; Prostaglandins, Leukotrienes and Medicine, 27: 9, 1987). In the present study, processed and unprocessed tea leaf extracts were given to rats to consume for a period of eight weeks. Cholesterol and thromboxane levels were measured in the serum obtained from clotting the blood at 37 degrees C. A significant reduction in thromboxane levels was observed in rats taking unprocessed tea extract. This reduction was equally distributed in adult as well as in juvenile rats. However no appreciable changes in the levels of thromboxane were noticed in the serum of rats taking processed tea extracts. This might be due to the presence of a labile component which is destroyed during the processing of green tea leaves. A decreased level of cholesterol was observed in rats consuming unprocessed tea extract. This decrease could be linked to the decrease in thromboxane levels as observed. Processed tea refers to commercially available tea of different brands while unprocessed tea refers to dried green tea leaves. Ali M, Afzal M, Gubler CJ, Burka JF. A potent thromboxane formation inhibitor in green tea leaves.Prostaglandins Leukot Essent Fatty Acids 40:281-283; 1990.

Reduced risk of esophageal cancer associated with green tea consumption.

BACKGROUND: Studies in laboratory animals have suggested inhibitory effects of green tea on the induction of some cancers, notably, esophageal cancer. However, only a few epidemiologic studies have evaluated green tea as a potential inhibitor of human esophageal cancer. PURPOSE: Our purpose was to evaluate the relationship between green tea consumption and the risk of esophageal cancer. METHODS: This esophageal cancer study was part of a larger multicenter, case-control study that included three other gastrointestinal sites (pancreas, colon, and rectum). Medical records of patients aged 30-74 years old who were diagnosed with esophageal cancer from October 1, 1990, through January 31, 1993, were identified from the Shanghai Cancer Registry, which covers 6.8 million people in the urban area of Shanghai, People's Republic of China. During the ascertainment period, records of 1016 eligible cases of esophageal cancer were identified. Control subject records were selected by frequency matching in accordance with the age-sex distribution of the four gastrointestinal cancers ascertained by the cancer registry during 1986-1987. Patient interviews were then conducted using a structured, standardized questionnaire to obtain information on demographic characteristics, residential history, height and weight, diet, smoking, alcohol and tea drinking, medical history, family history of cancer, occupation, physical activity, and reproductive history. RESULTS: Of the 902 patients interviewed, 734 (81.4%) had their disease pathologically confirmed. There were 1552 control subjects interviewed, including 240 alternates. All analyses of tea effects were conducted separately among men and women and all were adjusted for age. After further adjustment for other known confounders, a protective effect of green tea drinking on esophageal cancer was observed among women (odds ratio [OR] = 0.50; 95% confidence interval [CI] = 0.30-0.83), and this risk decreased (P for trend < or = .01) as tea consumption increased. Among men, the ORs were also below 1.00, although not statistically significant. ORs for green tea intake were estimated among those persons who neither smoked nor drank alcohol. In this subset, statistically significant decreases in risk among tea drinkers were observed for both men (OR = 0.43; 95% CI = 0.22-0.86; P for trend = .05) and women (OR = 0.40; 95% CI = 0.20-0.77; P for trend < .001). CONCLUSIONS: This population-based, case-control study of esophageal cancer in urban Shanghai suggests a protective effect of green tea consumption. Although these findings are consistent with studies in laboratory animals, indicating that green tea can inhibit esophageal carcinogenesis, further investigations are definitely needed.Gao YT, McLaughlin JK, Blot WJ, et al. Reduced risk of esophageal cancer associated with green tea consumption. J Natl Cancer Inst 86:855-858; 1994.

Inhibitory effect of tea catechins on collagenase activity.

A major purpose of this study was to examine inhibitory effect of the catechin derivatives from Japanese green tea Camellia sinensis on collagenase activity. The crude tea catechins, which contain (+)-catechin (C), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg), were tested for their ability to inhibit the prokaryotic and eukaryotic cell derived collagenase activities. Among the tea catechins tested, ECg and EGCg showed the most potent inhibitory effect on collagenase activity when an optimal concentration of tea catechins (100 micrograms/ml) was added to reaction mixture containing collagenase and collagen. Preincubation of collagenase with tea catechins reduced the collagenase activity as well. In contrast to ECg and EGCg, the other four tea catechins (C, EC, EGC, and GC) did not show any collagenase inhibitory effect. Our results suggest that the steric structure of 3-galloyl radical is important for the inhibition of collagenase activity. The collagenase activity in the gingival crevicular fluid from highly progressive adult periodontitis was completely inhibited by the addition of tea catechins. These results demonstrated that tea catechins containing galloyl radical possess the ability to inhibit both eukaryotic and prokaryotic cell derived collagenase.Makimura M, Hirasawa M, Kobayashi K, et al. Inhibitory effect of tea catechins on collagenase activity. J Periodontol 64:630-636; 1993.

Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan.

METHODS. The relation between green tea consumption and serum lipid concentrations was examined using cross-sectional data on 1,306 males who received the retirement health examination at the Self-Defense Forces Fukuoka Hospital between October 1986 and December 1988. RESULTS. After adjustment for rank, smoking, alcohol use, physical activity, and body mass index, serum total cholesterol levels were found to be inversely related to the consumption of green tea while no association was noted with serum triglycerides and high-density lipoprotein cholesterol. Adjusted mean concentrations of total cholesterol were 8 mg/dl lower in men drinking nine cups or more per day than in those consuming zero to two cups per day. Serum cholesterol levels were inversely associated with traditional Japanese dietary habits (intake of rice and soy bean paste soup) and positively associated with Westernized habits. Additional adjustment for these dietary variables did not alter the inverse relation between green tea and total cholesterol.Kono S, Shinchi K, Ikeda N, et al. Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan. Prev Med 21:526-531; 1992.

Anticarcinogenic effects of (-)-epigallocatechin gallate.

BACKGROUND. Our research objective is to develop nontoxic cancer chemopreventive agents and to apply these agents in treating humans. We are identifying agents that inhibit the process of tumor promotion in two-stage carcinogenesis experiments on mouse skin. METHODS. We review (a) the inhibitory effect of penta-O-galloyl-beta-D-glucose (5GG) on tumor promotion by teleocidin, one of the 12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters (5GG is structurally similar to (-)-epigallocatechin gallate (EGCG) and is isolated from hydrolyzed tannic acid); (b) the inhibitory effects of EGCG, the main constituent of Japanese green tea, on tumor promotion with two tumor promoters, teleocidin and okadaic acid, a non-TPA-type tumor promoter; (c) the mechanisms of action of EGCG, a single application of which reduced the specific binding of [3H]TPA and [3H]okadaic acid to a particulate fraction of mouse skin; and (d) the anticarcinogenic effects of EGCG on duodenal carcinogenesis induced by N-ethyl-N'-nitro-N-nitrosoguanidine in male C57BL/6 mice. EGCG is a nontoxic compound. CONCLUSION. We believe that the main constituent of Japanese green tea, EGCG, is a practical cancer chemopreventive agent available in everyday life.Fujiki H, Yoshizawa S, Horiuchi T, et al. Anticarcinogenic effects of (-)-epigallocatechin gallate. Prev Med 21:503-509; 1992.

Protective activity of tea and catechins against Bordetella pertussis

We examined the bactericidal activity of tea and catechins against Bordetella pertussis. Green tea, black tea and coffee showed marked bactericidal activity at their concentrations in beverages, while pu-erh tea killed the bacteria in a moderate way. (-) Epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) showed also marked bactericidal activity. Green tea and black tea also effectively blocked the adhesion of B. pertussis to HeLa and CHO cells, whereas ECGg and TF3 could not. EGCg and TF3 markedly inactivated leuco-lymphocytosis promoting activity of pertussis toxin. Black tea showed slight but significant inactivation of the activity, whereas green tea showed no inactivation. These results suggest that green tea, black tea, EGCg and TF3 might act as prophylactic agents against pertussis infection.Horiuchi Y, Toda M, Okubo S, et al. [Protective activity of tea and catechins against Bordetella pertussis]. Kansenshogaku Zasshi 66:599-605; 1992.

Tea components: antimutagenic and anticarcinogenic effects.

BACKGROUND. Tea from the Camellia sinensis species of the Theaceae family is one of the most ancient and, next to water, the most widely consumed beverage in the world. Since tea contains several polyphenols and since several other naturally occurring dietary polyphenols have shown antimutagenic effects in bacteria and anticarcinogenic effects in animal bioassay systems, we studied whether polyphenols extracted from Chinese green tea (GTP) also possess antimutagenic and anticarcinogenic effects. RESULTS. GTP and its constituent epicatechin derivatives were found to interact with hepatic cytochrome P450 (P450) and inhibited the P450-dependent mixed-function oxidase enzymes in skin and liver. GTP and its epicatechin derivatives exhibited antimutagenic effects in several test systems. GTP showed substantial anti-skin-tumor-initiating and anti-skin-tumor-promoting activities when assessed in murine skin tumorigenesis bioassay systems. In these model systems polyaromatic hydrocarbons, benzo[a]pyrene (BP), 3-methyl-cholanthrene, 7,12-dimethylbenz [a]anthracene, and (+)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrene (an ultimate carcinogenic metabolite of BP) were used as model skin carcinogens. The feeding of GTP in drinking water to SKH-1 hairless mice also afforded significant protection against ultraviolet-B-radiation-induced skin photocarcinogenesis . CONCLUSIONS. These data suggest that tea components possess antimutagenic and anticarcinogenic effects, and that they could protect humans against the risk of cancer by environmental agents.Mukhtar H, Wang ZY, Katiyar SK, Agarwal R. Tea components: antimutagenic and anticarcinogenic effects. Prev Med 21:351-360; 1992.

Anticaries effects of polyphenolic compounds from Japanese green tea.

The dental caries inhibiting effect of the extract from Japanese green tea, one of the most popular drinks in Japan, was studied both in vitro and in vivo. The crude tea polyphenolic compounds (designated Sunphenon) from the leaf of Camellia sinensis were found to effectively inhibit the attachment of Streptococcus mutans strain JC-2 (serotype c) to saliva-coated hydroxyapatide discs. Sunphenon was also inhibitory to water-insoluble glucan formation from sucrose by crude glucosyltransferase of S. mutans JC-2 (c). Among the tea catechins tested, (-)-epigallocatechin gallate and (-)-epicatechin gallate showed the most potent inhibition of the glucosyltransferase activity. Finally, significantly lower caries scores were observed in specific pathogen free rats infected with S. mutans JC-2 (c) and fed a cariogenic diet and/or drinking water containing 0.05% Sunphenon as compared with control rats not receiving polyphenolic compounds.Otake S, Makimura M, Kuroki T, et al. Anticaries effects of polyphenolic compounds from Japanese green tea. Caries Res 25:438-443; 1991.

Monoamine metabolites, iron induced seizures, and the anticonvulsant effect of tannins.

Intracortical injections of iron ions have been shown to induce recurrent seizures and epileptic discharges in the EEG. (-)-Epigallocatechin (EGC) and (-)-epigallocatechin-3-O-gallate (EGCG), isolated from green tea leaves, have been reported to prevent or diminish the occurrence of epileptic discharges induced by iron ions, and to inhibit catechol-O-methyltransferase. Iron ions significantly increased DOPAC and HVA levels in the intrastriatal perfusate 140 and 180 minutes, respectively, after injection. EGC and EGCG inhibited the increases induced by iron ions. Furthermore, EGCG decreased the HVA level in the perfusate 200 minutes after injection whether or not iron ions were injected. Iron ions had no effect on the 5-HIAA level, and EGC and EGCG raised it. These results suggest that formation of an epileptic focus induced by iron ions might be accompanied by activation of dopaminergic neurons, and that EGC and EGCG inhibit that hyperactivity.Kabuto H, Yokoi I, Mori A. Monoamine metabolites, iron induced seizures, and the anticonvulsant effect of tannins. Neurochem Res 17:585-590; 1992.

Radioprotective effects of (-)-epigallocatechin 3-O-gallate (green-tea tannin) in mice.

Long-term administration of (-)-epigallocatechin 3-O-gallate (EGCG) to mice through drinking water prevented radiation-induced increase of lipid peroxides in liver and significantly prolonged life span after lethal whole-body X-irradiation. The result indicates validity of this green-tea component as an orally active radio-protector of very low toxicity.Uchida S, Ozaki M, Suzuki K, Shikita M. Radioprotective effects of (-)-epigallocatechin 3-O-gallate (green-tea tannin) in mice. Life Sci 50:147-152; 1992.

Platelet aggregation inhibitors in hot water extract of green tea.

The effect of hot water extract of green tea on the collagen-induced aggregation of washed rabbit platelets was examined. The extract lowered submaximal aggregation and prolonged the lag time in a dose-dependent manner. After fractionation of the extract, it was revealed that the tea catechins (tannins) are active principles for inhibition and that ester-type catechins are more effective than free-type catechins. One of the ester type catechins, epigallocatechin gallate (EGCG), suppressed the collagen-induced platelet aggregation completely at the concentration of 0.2 mg/ml (= 0.45 mM). Comparing IC50 values of EGCG and aspirin it was found that the potency of EGCG is comparable to that of aspirin. Thrombin- and platelet activating factor (PAF)-induced aggregation was also inhibited by EGCG. The elevation of cyclic adenosine 3',5'-monophosphate (cAMP) level was not observed in EGCG treated platelets. Sagesaka-Mitane Y, Miwa M, Okada S. Platelet aggregation inhibitors in hot water extract of green tea. Chem Pharm Bull (Tokyo) 38:790-793; 1990.

Antibacterial and bactericidal activities of Japanese green tea

We found that extracts of Japanese green tea leaves inhibited the growth of various bacteria causing diarrheal diseases. All tea samples tested showed antibacterial activity against Staphylococcus aureus, S. epidermidis, Vibrio cholerae O1, V. cholerae non O1. V. parahaemolyticus, V. mimicus, Campylobacter jejuni and Plesiomonas shigelloides. None of the tea samples had any effect on the growth of V. fluvialis, Aeromonas sobria, A. hydrophila, Pseudomonas aeruginosa, Salmonella enteritidis, enteroinvasive Escherichia coli, enterohemorrhagic E. coli, enteropathogenic E. coli, enterotoxigenic E. coli, Enterobacter cloacae or Yersinia enterocolitica. Salmonella and Shigella showed susceptibilities different depending on the kind of Japanese green tea. Japanese green tea showed also bactericidal activity over S. aureus, V. parahaemolyticus and even enteropathogenic E. coli which was not sensitive when tested by cup method. The bactericidal activity was shown even at the drinking concentration in daily life.Toda M; Okubo S; Ohnishi R; Shimamura T. [Antibacterial and bactericidal activities of Japanese green tea]. Nippon Saikingaku Zasshi 44:669-672; 1989.

Antimicrobial and microbicidal activities of tea and catechins against Mycoplasma

We examined tea extracts, (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) for their antimicrobial and microbicidal activities against Mycoplasma. Green tea and black tea showed antimicrobial activities against M. pneumoniae. At a concentration of 0.2% green tea and black tea showed microbicidal activities against M. pneumoniae and M. orale but not against M. salivarium. Extracts of pu-erh tea showed a slight microbicidal activity against M. pneumoniae and M. orale. EGCg purified from green tea and TF3 from black tea markedly showed microbicidal activities against M. pneumoniae. M. orale and M. salivarium. These results suggest that tea and catechins can be used as prophylactic agents against Mycoplasma pneumoniae infection.Chosa H, Toda M, Okubo S, et al. [Antimicrobial and microbicidal activities of tea and catechins against Mycoplasma]. Kansenshogaku Zasshi 66:606-611; 1992.

additional research

Ru-erh  Tea is a category of black tea and is uniquely double fermented 

and aged giving it its special medicinal quality and reputation.