Green TeaPosting Date: 08/26/2002
Until a few years ago, tea might have seemed more appropriately addressed in a cookbook than in a book about herbs. This beverage is probably the most frequently consumed in the world after plain water. To be sure, it has the requisite ancient history, with its use going back more than three thousand years in China. Along with many other Chinese botanical medicines, it was discussed in The Herbal Classic of the Divine Plowman. A few centuries later, Chinese Buddhists espoused tea because it could help the devout stay awake during long meditations, and Taoists adopted it because it was believed to promote health and longevity. But in the West, tea was more often thought of as simply a soothing hot drink, and it was far more likely to be black tea than green. Recent research has shown that the Buddhists and the Taoists may have been right. Green tea in particular appears to have certain health benefits. Green and black tea come from the same plant, but the fermentation process required to turn tea black appears to alter the chemistry of the leaf somewhat. Oolong tea is produced by means of a partial fermentation process. Although green, oolong, and black are the principal categories for tea, the Chinese classify it in a much more complex fashion, with as many as 330 kinds of tea (cha) recognized. In a typical store offering tea in China, the inventory might include one hundred types of cha. Active Ingredients The methylxanthine alkaloids caffeine, theophylline, and theobromine comprise between 1 and 5 percent of tea. These compounds have similar but not identical actions; caffeine is usually the dominant one. Depending on the variety of tea and the way it was prepared, a cup (a proper six-ounce teacup) may contain from 10 to 50 mg of caffeine. Low doses of caffeine may actually slow heart rate slightly, while at higher doses this stimulant can speed heart rate or even contribute to mild rhythm abnormalities. Related Stories |
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