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Green Tea

Green tea provides broad protection against four major categories of carcinogens:

Green tea's anticancer effects come from compounds called polyphenols. Polyphenolic compounds demonstrate chemopreventive activity in animal and tumor models. Moreover, epidemiological studies have shown green tea might be effective in the prevention of certain human cancers. Green tea has been shown to slow the production of hydrogen peroxide and other reactive free radicals associated with the formation of cancer, and is a great overall immune booster.

Your green tea was found to have very high content of the most important anti-oxidants. This was reflected in high anti-oxidant activity of the tea.

Green Tea - History and Ethno-botanical Background

All tea comes from the leaves of the Camellia Sinensis tree. Tea gardens pluck or prune the C. Sinensis year round and the plant more resembles a bush, but allowed to grow wild, it reaches heights of about thirty feet.

Three types of tea are produced from the leaves - green teas, black teas, and oolong teas. While there are about three thousand variations of tea, all are derived from the Camellia Sinensis. Some herbal infusions, such as chamomile, are often referred to incorrectly as tea. These infusions normally contain leaves, flowers, and other dried ingredients from other plants.

Green tea, which is unfermented tea, remains the most popular tea in Asian countries such as China and Japan. In fact, up until the eighteenth century, it was also the most popular form of tea in Britain as well. Imports of green tea into the United States outpaced black tea until about 1915. Much of the tea dumped into the Boston harbor during the Boston Tea Party, was in fact green tea. Thus, it is unlikely that the harbor turned to a copper color!

About ninety percent of the world's green tea is produced in China. While most of the world's black tea comes from countries such as Sri Lanka (Ceylon), India, Kenya, Indonesia and Argentina, these countries produce little, if any, green tea. Several hundred varieties of green tea are made in China alone. Some of the most popular include Gunpowder, Hyson, Imperial Green, and Gyokuro (Japan). A cup of green tea is generally much lighter than other teas. While Asian cultures have believed for centuries that green tea has properties beneficial to human health, modern science is just now discovering that this may be true.

Manufacture of Tea

Differences between green, black, and oolong teas occur during the processing of the tea leaves.

Plucking

All types are normally hand plucked. Pluckers take only the bud and two leaves, as only young leaves produce good quality tea. Machine plucked tea is usually inferior.

Withering

The next step in manufacturing is withering. Tea leaves are laid out and allowed to wilt for several hours. Leaves are laid out in bamboo trays or in withering beds indoors. Withering reduces the moisture content in the leaves and prepares them for the next step. Withering can be omitted during the production of green tea, but is crucial in black tea manufacture.

Steaming

This process differentiates green tea from other types. After withering, green tea leaves are immediately steamed, baked, or pan heated. This crucial step in green tea manufacture prevents the oxidation (fermentation) of the leaves so that they remain green.

Rolling

Green tea is very often hand rolled, but mechanical rollers are used as well. The rolling process gives the leaves their appearance. During green tea manufacture, leaves are usually steamed rolled and steamed alternatively. Tightly rolled leaves are an indication of good quality tea.

Firing

Green tea leaves are given a final firing to dry the leaves and ensure no oxidation of the leaves occurs. The firing of leaves is done in ovens.

Scientific Background

Green tea is an aqueous infusion of dried unfermented leaves of Camellia sinensis (family Theaceae) from which numerous biological activities have been reported including antimutagenic, antibacterial, hypocholesterolemic, antioxidant, antitumor and cancer preventive activities. From the aqueous-alcoholic extract of green tea leaves, six compounds (+)-gallocatechin (GC), (-)-epicatechin (EC), (-)- epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)- epigallocatechin gallate (EGCG) and caffeine, were isolated and purified. Together with (+)-catechin, these compounds were tested against each of four human tumor cells lines (MCF-7 breast carcinoma, HT-29 colon carcinoma, A-427 lung carcinoma and UACC-375 melanoma). The three most potent green tea components against all four tumor cell lines were EGCG, GC and EGC. EGCG was the most potent of the seven green tea components against three out of the four cell lines (i.e. MCF-7 breast cancer, HT-29 colon cancer and UACC-375 melanoma). On the basis of these extensive in vitro studies, it would be of considerable interest to evaluate all three of these components in comparative pre-clinical in vivo animal tumor model systems before final decisions are made concerning which of these potential chemopreventive drugs should be taken into broad clinical trials.

Green Tea, dried without fermentation, contains a higher value of Catechin Polyphenols that have antioxidant properties against cancer. Each cup of Green Tea contains a total of 1.5 grams (150 mg) of epigallocathechin-3gallate ( EGCG) that acts against urokinase, which is often found in large amount in human cancers. EGCG attaches to it and prevents it from spreading cancer in humans, and reduces the size of the cancers already formed.

The scavenging effects of tea catechins and their epimerized, acylated, and glucostylated derivatives on 1,1-diphenyl-2- picrythydrazyl (DPPH) radical were evaluated by electron spin resonance spectrometry. Tea catechins and their epimers were shown to have 50% radical scavenging ability in the concentration range of 1 to 3 microM. No significant differences were observed between the scavenging activities of tea catechins and their epimers, and, hence, the scavenging effects of catechins are not dependent on their sterical structure. The relationship between scavenging ability and the structure of tea catechins was also examined with acylated and glucosylated catechin derivatives. It is suggested that the galloyl moiety attached to flavan-3-ol at 3 position has a strong scavenging ability on the DPPH radical as well as the ortho-trihydroxyl group in the B ring, which elevates the radical scavenging efficiency above that of the ortho-dihydroxyl group; as has been recognized in other flavonoids such as flavones. The results obtained from the reactivity of tea catechins with the DPPH radical at different pHs suggest not only that the ortho-trihydroxyl group and the galloyl moiety contribute to maintaining the DPPH radical scavenging ability more effectively in a wide range of conditions from acidic to alkaline, but also that the radical scavenging efficiency of the ortho- dihydroxyls in the B ring is limited in neutral to alkaline regions. The difference between the scavenging abilities of the trihydroxyls (probably in the galloyl moiety) and the dihydroxyls can be explained in terms of redox potentials. It is concluded that the ortho- trihydroxyl group in the B ring and the galloyl moiety at 3 position of flavan-3-ol skeleton are the most important structural features for displaying an excellent scavenging ability on the DPPH radical.

Catechin

Description: Catechin is a bioflavonoid that is found in Green Tea. It works both alone and in conjunction with other flavonoids found in tea, and has both antiviral and antioxidant qualities.

Catechin has been shown helpful in the treatment of viral hepatitis. Supplementation of 500 to 750 mg three times daily appears effective.

It also appears to prevent oxidative damage to the heart, kidney, lungs, and spleen.

Preliminary studies of animals show that catechin prevents oxidative damage to blood as well. When taken as part of Green Tea, catechin also appears to inhibit the growth of stomach cancer cells.

NAME	(+)-Catechin D-Catechin Cyanidanol (2R-trans)- 2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H-1-Benzopyran- $3,5,7-triol
FORMULA	C15H14O6

SELECTED RECENT GREEN TEA NEWS

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 that 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-preventing 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.