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Tea is a healthy brew
Tea is the world's second most popular beverage (after water). In addition to being a mild stimulant -- it contains caffeine -- green tea has recently emerged as a good-health promoter and cancer preventative because it is remarkably rich in powerful antioxidant compounds.
Common Uses- As a beverage with a mildly stimulant effect (less than coffee)
- In the prevention of cancer, heart disease, and stroke
- To promote better health
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Tea Facts
Tea contains three stimulant chemicals (caffeine, theobromine, and theophylline), which accounts for its use in traditional herbal medicine. All three stimulants open (dilate) the bronchial passages (bronchodilators), thus validating the traditional use of tea as a treatment for colds, flu, asthma, and other respiratory problems. (Physicians still sometimes prescribe pharmaceutical preparations of theophylline to treat asthma.) [1] When steeped for around three minutes, the typical cup of tea contains about 40 mg of caffeine, compared with 100 mg in a cup of brewed coffee. [2]
Tea, whether green (unfermented), black (fermented), or oolong (semi-fermented), also contains astringent tannins, which help counteract unusual fluid loss through the digestive tract. This binding action accounts for its traditional use as a diarrhea treatment. Tea continues to be used as a diarrhea treatment today. It's part of the so-called "BRATT" diet that many doctors recommend: bananas, rice, applesauce, tea, and toast. [3]
Tea is also a good source of fluoride, which helps prevent tooth decay. Both green and black teas contain more fluoride than fluoridated water. The tannins in tea also help fight the bacteria that cause tooth decay. [4]
But in recent years, tea -- specifically green tea -- has rocketed to new prominence because of the discovery that the polyphenols it contains are potent antioxidants, and because of studies showing that it helps prevent heart disease and several cancers. Much of this research has been conducted in Japan using green tea, the form of tea the Japanese drink. [5]
Green tea was shown in the early 1980s to have cancer-preventive value in laboratory animals. The first study to show this effect in humans was published in 1988. Researchers in Kyushu, Japan, compared the diets and lifestyles of 139 people with stomach cancer, and 2,852 cancer-free people used as controls. After eliminating other variables, the study showed that as green tea consumption increased, stomach cancer risk decreased. Drinking at least 10 cups a day conferred the greatest protective benefit. [6]
Since then, green tea has been shown to reduce risk of several other cancers: esophageal [7], colorectal [8], pancreatic [9], lung [10, 11], and breast [12]. The breast cancer study is particularly intriguing. Japanese researchers have shown that compared with breast cancer sufferers who drink little or no green tea, those who drink a great deal of it regularly (eight to 10 cups a day) have milder cases of breast cancer at diagnosis (fewer positive lymph nodes), a greater likelihood of estrogen-positive disease (which correlates with improved prognosis), less risk of metastasis, less likelihood of recurrence, and longer survival.
The antioxidants in green tea also help prevent heart disease. University of Kansas researchers have found that some of the antioxidants in green tea are 25 times as powerful as vitamin E, an antioxidant nutrient often recommended to prevent heart attack. [13] A Dutch study shows that compared with people who drink no tea, those who drink one to two cups of tea a day have significantly less atherosclerotic narrowing of their arteries, the underlying cause of heart disease and most strokes. [14]
Do you have to drink green tea to realize these health benefits? Yes and no. The specific antioxidant believed to account for tea's value in preventing cancer and heart disease is epigallocatechin gallate (EGCG). It is present in all forms of tea, but in much higher concentrations in unfermented green tea. In test-tube studies, black tea has been shown to have only one-tenth to one-hundredth of green tea's antioxidant punch. [15]
On the other hand, some studies show that black tea confers health benefits; for example, the Dutch study of atherosclerosis mentioned above.
But another Dutch study involving 58,279 men and 62,573 women who were followed for more than four years showed that black tea had no value in preventing lung, breast, or colorectal cancers, three diseases green tea has been shown to prevent. [16]
Bottom line: Green tea is best for prevention of cancer and cardiovascular disease. Black and oolong teas contain significantly less of the antioxidants found in green tea, but are not entirely devoid of them.
For those used to the rich, full-bodied flavor of black tea, green tea tastes thin and watery at first. But over time, you may come to appreciate its delicate flavor.
Sources
1 Snow, J. "Herbal Monograph: Tea (Camellia sinensis)," The Protocol Journal of Botanical Medicine Autumn 1995.
2 Brody, J. "Tea: The Latest Health Food," The New York Times 9-7-99.
3 Anon. "Green Tea," The Review of Natural Products 2-99, p. 2.
4 Ibid.
5 Muir, M. "(Green) Tea Time," Alternative and Complementary Therapies 2-98. p. 43-47.
6 Kono, S., et al. "A Case-Control Study of Gastric Cancer and Diet in Northern Kyushu, Japan," Japanese Journal of Cancer Research (1988) 79:1067.
7 Gao, Y.T., et al. "Reduced Risk of Esophageal Cancer Associated with Green Tea Consumption," Journal of the National Cancer Institute (1994) 86:855.
8 Ji, B.-T., et al. "Green Tea Consumption and the Risk of Pancreatic and Colorectal Cancers," International Journal of Cancer (1997) 70:255.
9 Ibid.
10 Ohno, Y., et al. "Tea Consumption and Lung Cancer Risk: A Case-Control Study in Okinawa, Japan," Japanese Journal of Cancer Research (1995) 86:1027.
11 Tewes, F., et al. "Lung Cancer Risk and Mutagenicity of Tea," Environmental Research (1990) 52:23.
12 Nakachi, K., et al. "Influence of Drinking Green Tea on Breast Cancer Malignancy Among Japanese Patients," Japanese Journal of Cancer Research (1998) 89:254.
13 Anon. "Green Tea May Prevent Cancer, Heart Disease," Modern Medicine 12-97, p. 9.
14 Anon. "More Evidence That Tea May Prevent Disease," The New York Times 10-11-99.
15 Rattloff, J. "Green Tea Belittles Cancer," Science News 1-2-99, p. 15.
16 Goldbohm, R.A., et al. "Consumption of Black Tea and Cancer Risk: A Prospective Cohort Study," Journal of the National Cancer Institute (1996) 88:93.
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Tea is a small evergreen tree that grows up to 30 feet tall in the wild. However, in cultivation around Asia, it is pruned into a bushy shrub. Its leaves are processed into all forms of tea. Green tea, preferred in Japan and much of China, is simply the dried leaf. Black tea, preferred in Great Britain, Europe, and the U.S., is dried and broken, and the enzymes within are allowed to ferment or oxidize. Oolong is semi-fermented. Teas are also named for the place the leaves were grown (Ceylon, Darjeeling, etc.). [17]
Tea has been used in Chinese medicine for at least 3,000 years as an astringent to treat headache, diarrhea, dysentery, colds, cough, asthma, and other respiratory problems. By the 8th century, it was enjoyed from Japan to Indonesia to India.
The Dutch East India Company first brought it to Holland in 1610, and by 1640, black tea had become popular with the British upper class. They drank it as an afternoon stimulant around 4 p.m., which is still known as "tea time."
Demand for tea spurred Britain's colonization of India, Ceylon (Sri Lanka), and Hong Kong. By the late 18th century, tea was an integral part of British culture, and around the world people of English descent rebelled against any threat to their tea supply. That's what happened in England's North American colonies in 1773, when the British Parliament levied a tax on the colonies' tea, substantially raising its price. Outraged residents of Massachusetts rioted. They stormed tea ships in Boston harbor and dumped enormous quantities of the herb overboard. The Boston Tea Party helped trigger the American Revolution. [18]
Since then, coffee and soft drinks have supplanted tea as America's favorite stimulant beverages. Yet tea, both hot and iced, remains quite popular. U.S. tea sales now top $4 billion a year, with about three-quarters of that amount spent on iced tea. [19]
Instructions
Use 1 to 2 teaspoons of tea per cup of boiling water. Steep to taste.
Sources
17 Snow, J. "Herbal Monograph: Tea (Camellia sinensis)," The Protocol Journal of Botanical Medicine Autumn 1995.
18 Castleman, M. The Healing Herbs. New York: Bantam, 1995, pp. 504-505.
19 Keating, B. "Tea Sales Moving Full Steam Ahead," Natural Foods Merchandiser 7-95.
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Warnings
All forms of tea contain caffeine and other stimulants. Tea contains about half the caffeine of coffee and, as a result, is less likely cup-for-cup to cause insomnia, anxiety, or jitters. But if you are particularly sensitive to caffeine, or if you consume a great deal of tea, you may experience these effects.
Large amounts of tea may cause stomach upset. Allergic reactions are also possible.
Some research has linked caffeine to an increased risk of birth defects. Pregnant women should discuss tea consumption with their prenatal care providers. [20]
Sources
20 Anon. "Green Tea," The Review of Natural Products 2-99, p. 4.
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Sources & Further Reading
Books
1. Castleman, M. The Healing Herbs. New York: Bantam, 1995, pp. 504-505.
Find more books on health and wellness at  barnesandnoble.com.
Articles
1. Anon. "Green Tea May Prevent Cancer, Heart Disease," Modern Medicine 12-97.
2. Anon. "Green Tea," The Review of Natural Products 2-99.
3. Anon. "More Evidence That Tea May Prevent Disease," The New York Times 10-11-99.
4. Brody, J. "Tea: The Latest Health Food," The New York Times 9-7-99.
5. Gao, Y.T., et al. "Reduced Risk of Esophageal Cancer Associated with Green Tea Consumption," Journal of the National Cancer Institute (1994) 86:855.
6. Goldbohm, R.A., et al. "Consumption of Black Tea and Cancer Risk: A Prospective Cohort Study," Journal of the National Cancer Institute (1996) 88:93.
7. Ji, B.-T., et al. "Green Tea Consumption and the Risk of Pancreatic and Colorectal Cancers," International Journal of Cancer (1997) 70:255.
8. Keating, B. "Tea Sales Moving Full Steam Ahead," Natural Foods Merchandiser 7-95.
9. Kono, S., et al. "A Case-Control Study of Gastric Cancer and Diet in Northern Kyushu, Japan," Japanese Journal of Cancer Research (1988) 79:1067.
10. Muir, M. "(Green) Tea Time," Alternative and Complementary Therapies 2-98.
11. Nakachi, K., et al. "Influence of Drinking Green Tea on Breast Cancer Malignancy Among Japanese Patients," Japanese Journal of Cancer Research (1998) 89:254.
12. Ohno, Y., et al. "Tea Consumption and Lung Cancer Risk: A Case-Control Study in Okinawa, Japan," Japanese Journal of Cancer Research (1995) 86:1027.
13. Rattloff, J. "Green Tea Belittles Cancer," Science News 1-2-99.
14. Snow, J. "Herbal Monograph: Tea (Camellia sinensis)," The Protocol Journal of Botanical Medicine Autumn 1995.
15. Tewes, F., et al. "Lung Cancer Risk and Mutagenicity of Tea," Environmental Research (1990) 52:23.
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