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A cup of Green Tea

Noazesh Ahmed

Better to be deprived of food for three days, than tea for one. (Ancient Chinese Proverb)

What makes green tea a miracle drink? Is any other beverage reputed to have as many health benefits as green tea? The Chinese have known about the medical benefits of green tea since ancient tines, using it to treat everything from headache to depression. As early as mid two thousand BC, green tea was known as a beneficial herbal drink. Many historians give credit to emperor Sen Nung of China for discovering medical value of green tea along with Naxvoxmica, Euphrada, and Datura experimenting on himself in 2227 BC. In the 4th century BC followers of Tao and Confucius were accustomed to drinking green tea to fight against fatigue and pain. In mid 8th century AD, Chinese poet Lu Hi wrote, "Drinking tea makes your body cool and soothing. It helps to behave like a selfrestrained gentleman. When one is thirsty or depressed and feel pain in four limbs, drink several cups of tea."

First, we must know the difference between green tea and black tea which we often drink with milk and sugar. The main difference between the green and black tea is summarised here. Both are made from same kind of tea leaf (Scientific name of the tea plant is Camellia Sinensis) depending on the processing methods. In green manufacture, plucked tea leaves are subjected to hot air to hot air or steam treatment (160F) for a short time to inactivate the polyphenol oxidase enzyme present in the leaf so that polyphoenol remains unoxidised. Unoxidised polyphenol contains catechin compounds such as gall catechin, epigall catechin gallate (EGCG) etc. EGCG remains high in green tea. In general, the liquor of green tea is lemon green in colour. Whereas in the manufacture of black tea, lucked tea leaf goes through oxidation process commonly known as fermentation by cutting and rolling for mixing unoxidiscd polyphenol with copper protein oxidase enzyme and turns the unxoidised polyphenol to the theaflavins and thearubizins. These two chemical compounds give black tea liquor its bright red in colour. As a result, presence of EGCG in black tea is insignificant. Here lies the fact that green tea rich in EGCG has a beneficial antioxidant for human health.

Health Benfits
Today, scientific research in both Asian and western universities and research centres is providing hard evidence for health benefits long associated with drinking green tea. For example, in 1994 the journal of the National Institute of America published the result of an epidemiological study indicating that drinking green tea reduced the risk of esophagal cancer in Chinese men and women by nearly sixty percent. University of Purdue (USA) researchers recently concluded that a compound (EGCG) in green tea inhibits the growth of cancer cells. A vast number of research in many distinguished universities and research centres in American and Europe also indicate that drinking green tea lowers total cholesterol levels, as well as improving the ratio of good (HDL) cholesterol to bad cholesterol (LDL)

To sum up all the research findings for the last two decades, here are just few medical conditions in winch drinking green tea is reported to be helpful: Cancer, rheumatoid arthristis, high cholesterol levels, Cardiovascular disease, bacterial and viral infection, impaired immune function.

The secret of green tea lies in the fact it is rich in catechin polyphenols, particularly epigallocataching gallale. EGCG is a powerful antioxidant: besides inhibiting the growth of cancer cells, it kills cancer cells without harming healthy tissue. It has also been effective in lowering LDL cholesterol levels, and inhibiting the abnormal formation of blood clots. The latter takes on added importance when you consider that thrombosis (the formation of abnormal blood clots) is the leading cause of heart attacks and stroke.

Links are being made between the effects of drinking green tea and the "France Paradox". For years, researchers were puzzled by the fact that, despite consuming a diet rich in fat, the French have a lower incidence of heart diseases than Americans. The answer was found to lie in red wine, which contains resveratrol, a polyphenol that limits the negative effects of smoking and fatty diet. In a 1997 study, researchers from the University of Kansas determined that EGCG is twice as powerful as resveratrol, which may explain why the rate of heart disease among Japanese men is quite low, even though approximately seventy-five percent are smokers.

New evidence is emerging that green tea can even help dieters. In November, 1999, the American Journal of Clinical Nutrition published the results of a study at the University of Geneva in Switzerland. Researchers found that men who were given a combination of caffeine and green tea extract burned more calories than those given only caffeine or a placebo.

Green tea can even help prevent tooth decay! Just as its bacteria-destroying abilities can help prevent food poisoning, it can also kill the bacteria that causes dental plaque. Meanwhile, skin preparations conataining green tea-from deoderants to creams-are starting to appear on the market.

Bangladesh produces generally black tea like India and Sri Lanka, However, the country manufactures about 3m kg of green tea annually in one garden, Jagcherra tea Estate of James Finlay. A major portion of the tea is exported to Pakistan. Due to its astringent flavour it is not popular to western markets. They favour green tea of mellowed qualities which is produced from small leaf china variety by China and Japan. So the rise of internal consumption would be a key factor for the expansion of green tea in Bangladesh.

Dr. Noazesh Ahmed is a tea Scientist, Former Agricultural Adviser of the Asian Developments Bank to the Mekong Valley Developments Project in South East Asia.


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