Types of Green Tea - There is quite a wide variety of green teas to choose from. With all the choices out there, let's take a look at some of the more common types that you may run into....
Sencha - 85% of Japan's tea harvest is in the form of sencha. This tea is grown in the full sun, and is harvested 3-4 times per year. The quality of the tea goes down as the year progresses, with the first harvest, known as Shincha (see below), condidered to be the best.
Shincha - Shincha means "New Tea", the term being derived from the fact that it comes from the buds of the first harvest of Sencha in late April to early May. Shincha is usually a higher quality tea, and in fact has the highest polyphenol content of all the green teas.
Gyokuro - One of the most expensive teas grown in Japan, this item is grown under 90% shade for two weeks before harvesting, and only the first flush is used. Contrary to popular opinion, gyokuro has slightly less polyphenols than a high grade of sencha (shincha), but does have a slightly higher amount of free amino acids, as well as theanine content. Due to it's lower tannin content, gyokuro has a mellower, sweeter, less astringent taste when compared with sencha.
Kabuescha - Somewhat of a cross between shincha and gyokuro, this item is grown under 40-50% shade for one to two weeks. A high quality tea, only the first flush is used for this product.
Matcha - Famous for it's use in the tea ceremony, matcha is grown in the same fashion as gyokuro. When processed, however, the leaves are dried but not rolled. Only the soft parts of the leaf are used, resulting in what is known as tencha. The tencha is then ground into a talcum-like powder and becomes matcha. The polyphenol content of matcha is about half that of sencha or gyokuro, however it has the highest concentration of free amino acids and theanine of all the green teas.
Ryokucha - Powdered sencha, similar to matcha except that is is ground from sun grown sencha instead of shade grown gyokuro.
Ujicha - Although most tea production in Japan occurs in Shizuoka, the small area south of Kyoto known as Uji produces some of the highest quality green teas available. You may often encounter various types of items with "Uji" tacked on to the front, and is often, but not always, the mark of a higher class of tea.
Bancha - Harvested from the last harvest, it is considered to be of a lesser quality than regular sencha. Nevertheless, it is quite tasty when iced.
Kukicha - Generally low grade, made from the stems sencha.
Kariganecha - Made from the stems of gyokuro instead of sencha. When blended with sencha, it is known as "Karigane Sencha", and gives a nice, sharp taste.
Hojicha - This is bancha that has been baked. Instead of having a green color, the heat treatment emparts a red color, giving it a unique taste. Since it is caffeine free, this item is often served in Japan to patients in hospitals or to children. Quite delicious iced.
Fukamushicha - Sencha that, during processing, is steamed for a longer period of time (90 seconds) in comparison to the normal 30 second steam time. Steaming time is usually dependant on the leaf used. Leaves grown at different elevations and under differing conditions will require different steaming times, as judged by an expert.
Genmaicha - Sencha mixed with brown puffed rice. Quite delicious.
DRINKING GREEN TEA MAY AID IN WEIGHT LOSS
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.
FURTHER RESEARCH IS NEEDED. 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 conslusions.
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
All tea comes from the
leaves of the Camellia Sinensis tree. Tea gardens pluck or prune the
Camellia Sinensis year round and the plant more resembles a bush, but
allowed to grow wild, it reaches heights of about thirty feet.
Japanese Green Tea production
Machine rubing tea production method
Judgemant of Japanese green tea
In judging aroma, color, taste, two 3g of Japanese green
teas are put each tea cup of balances.
An overview of the basic processing methods for various green teas