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General Health: Green Tea Extracts
Whether you believe any of these stories or not, we do know that the leaves from this evergreen shrub have been consumed for over 4,000 years and that they have always been known for health. Some historians assert that tea was first consumed in China to flavor water that was boiled to protect people from bacterial contamination. In 1211 a.d., a Japanese monk named Eisai wrote a book called Maintaining Health by Drinking Tea in which he said, "Tea is a miraculous medicine for the maintenance of health. Tea has the extraordinary power to prolong life. Anywhere a person cultivates tea, long life will follow. In ancient and modern times, tea is an elixir that creates the mountain dwelling immortal." The sixteenth-century European explorers who first tried tea reported that it was used to treat fever, headache, joint pain, and stomachache. Green Tea Polyphenols are members of the flavonoid family. They are catechins made of several ringlike structures. Each of these structures has chemicals attached to it called phenol groups, hence the name polyphenols (poly means "many").
Four of these polyphenols are of particular interest: epicatechin (EG), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG). In green tea, about half of the polyphenols are EGCG. EGCG is a powerful antioxidant and has been found to be 20 times stronger than vitamin E in protecting brain lipids, which are very susceptible to oxidative stress. (Chem Pharm Bulletin 38 [1990]: 1049) In animal studies with mice, ECG has been shown to reduce the rate of lung, skin, and stomach cancer. (Preventative Medicine 21) Green tea is regarded as an antioxidant. The polyphenols, especially EGCG, prevent free radical damage and have even been found to detoxify free radicals produced by the environmental toxin paraquat. (Carcinogenesis 10 [1989]: 1003) As a whole, human studies indicate that consuming green tea can lower the rate of esophageal cancer, mouth cancers, and gastric cancers. Recent research indicates that green tea may reduce the risk of some forms of stomach cancer. Surveys of Japanese tea drinkers show that those who consume four to six cups of green tea a day have lower levels of breast, esophageal, liver, lung, and skin cancers than those who consume less green tea or none at all. At a meeting of the American Chemical Society in 1991, researchers reported that even cigarette smokers who consumed green tea had a 45 percent lower risk of cancer than nontea drinkers. As an antitumor agent, green tea has an antimutation factor that helps DNA (deoxyribonucleic acid) to reproduce accurately rather than in mutated forms. Green tea’s catechin content is believed to be responsible for this effect. Even though Japan has one of the highest rates of smokers in the world, they have one of the lowest rates of lung cancer of any developed nation. Green tea is a hypotensive, lowering blood pressure and helping to increase blood flow to the heart. Many Asians have long consumed green tea with meals, and this practice is now showing to reduce arterial disease. Many heart attacks are brought on by blood platelet aggregation and green tea prevents the blood from "clumping together" and forming clots that can lead to stroke. One study indicates that 6,000 Japanese women who were nondrinkers and nonsmokers over 40 who drank about five cups of green tea a day had a 50 percent decrease in the risk of stroke. (Natural Health [March/April 1994]) Whereas coffee can elevate cholesterol levels, green tea helps lower them. (HerbalGram 37 [1996]) The catechin content of green tea helps to break down cholesterol and increase its elimination through the bowels. Green tea also helps to keep blood sugar levels moderate.
Green tea helps to prevent dental decay by inhibiting the bacteria streptococcus mutans, which are responsible for plaque formation. It can also help inhibit the bacteria that cause halitosis. Green tea is traditionally consumed after a meal to leave the mouth feeling fresh and clean. It is currently being studied to see if it will help prevent osteoporosis. Green tea is also used topically and in this case is known as a styptic, which helps stop bleeding when applied topically. It has been used lukewarm on open wounds, acne, athlete’s feet, and sunburn, and appears to protect the skin from damage from ultraviolet radiation exposure. Researchers are not yet sure why this works but think it may be due to its antioxidant activity. Excessive use of green tea can cause nervous irritability and aggravate ulcers, and those with hypertension and insomnia should consider avoiding it. With so many health benefits, it would be wise for more Americans to consider switching from coffee to tea. I think I’ll go brew some tea right now. Brigitte Mars is an herbalist and nutritional consultant from Boulder, Colorado, who has been working with natural medicine for 30 years. She teaches herbology, has a weekly Boulder radio show called Naturally, and is the formulator for UniTea Herbs. She is the author of Elder; Herbs for Healthy Hair, Skin, and Nails (Keats Publishing), and of a comprehensive CD-ROM on herbs, The Herbal Pharmacy. This is available from Hale Software at 1-800-856-6081. Get a free demo program at http://www.halesoftware.com. |
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Tea (Camellia sinensis) has a history of mythological proportions, no matter where in the world you look. In the West, the word Thea, which is Greek for "goddess," gives tea its name. In the East, in China, a popular legend has Chinese emperor Shen Nung "discovering" tea when some leaves from a nearby tea bush blew into a pot of water he was boiling for drinking water. In India, ancient legend tells the tale of Siddhartha Guatma, the founder of Buddhism, despairing after falling asleep during meditation. He was so upset with himself that he ripped off his eyelids and threw them to the ground where they rooted and grew into the first tea plant, with the shape of its leaves resembling the eyelid.
Of all three types of tea (green, black, and oolong), green tea contains the most polyphenols: about 15 percent to 30 percent of its weight. The polyphenols in green tea are recognized as anticarcinogenic, and this polyphenol content, along with the naturally occurring vitamin C, helps strengthen blood vessel walls.
Green tea has been used throughout history to improve ailments such as allergies, arteriosclerosis, asthma, cholera, colds, congestion, coughs, depression, diarrhea, digestive infections, dysentery, fatigue, hangovers, hepatitis, migraines, and typhus. Tea helps to constrict the blood vessels, thereby reducing the throbbing pain of an impending headache. In China, medicines made from the polyphenols in tea are used to treat hepatitis, nephritis, and leukemia.
