Dear Sinic Savant,
My wife has been trying for some time to convince me to give up my long-standing coffee habit in favor of green tea, which she claims is a much healthier alternative. I’ve asked her what it is that’s supposed to be so healthy about tea, but all she’s been able to tell me is that Japanese and Chinese green tea-drinkers have a lower incidence of certain cancers. What’s so great about green tea, and does this apply to other types of tea like Early Grey or Darjeeling or Oolong?
Yours,
Coffee Achiever
Dear Achiever,
Listen to your wife’s advice: She has science on her side. Studies conducted over the last decade are unanimous in their endorsement of green tea, drunk in moderation. Green tea contains more fluoride than fluorinated water and is (perhaps surprisingly) a good source of vitamin C, containing as much by dry weight as lemon. And of course there’s the caffeine, fuel of the new economy, which should make green tea an attractive alternative in your case.
But by far the greatest share of interest in green tea’s healthful properties focuses on the polyphenols it contains. Polyphenols are a type of flavonoid, and they occur in tea in remarkably high concentration: Polyphenols account for as much as 30% of the dry weight of some green teas.
The research findings to which your wife refers are probably those that have focused on the anti-oxidant, anti-carcinogenic properties of these polyphenols. Numerous studies on Japanese green tea drinkers have shown markedly lower incidence of lung cancer when compared with other industrialized societies,even though smoking rates in Japan are among the highest in the industrialized world. There is strong evidence to indicate that consuming green tea can also lower the rate of esophageal cancer, mouth cancers, and gastric cancers as well. 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. Researchers reported that even cigarette smokers who consumed green tea had a 45 percent lower risk of cancer than non-tea drinkers. As an anti-tumor agent, green tea has an anti-mutation factor that helps DNA to reproduce accurately rather than in mutated forms. Green tea polyphenols also help to prevent free radical damage to genetic material and to detoxify certain free radicals.
If these anti-carcinogenic properties aren’t enough to convince you, then perhaps green tea’s benefits to the cardiovascular system will help you make the switch. Unlike coffee, which some studies claim actually increases blood cholesterol, green tea seems to help break it down and helps its elimination through the bowels. Green tea seems to lower blood pressure by increasing vascular circulation to the heart, and by preventing platelet aggregation and clot formation can reduce the risk of 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])
Still unconvinced? Green tea also seems to inhibit the growth of certain bacteria shown to be responsible for halitosis — bad breath — and to prevent the formation of plaque. So along with the naturally-occurring fluoride, tea is good for oral health. Coffee, on the other hand, can leave you’re your breath pretty rank and can, with its high acid levels and propensity to stain, do some nasty things to your teeth.
There are three basic types of tea drunk in China today: Green tea, which is completely unfermented; black (or red) tea, which is totally fermented and includes the Darjeeling and Earl Grey that you mention; and Oolong (Wulong) tea, which is partially fermented. Although all three types do contain polyphenols, they occur in highest concentrations in green tea. Fermentation seems to break down the vitamin C content in tea, too. So your best bet is still to go with green tea. Remember, many so-called “herbal teas” on the market today don’t actually contain real tea leaves — the leaves of the Camellia sinensis — and do not therefore provide the health benefits described above.
So make the switch, and live longer. And thank your wife for the very good advice!
