Dear Mr. T,
In China, health-giving properties have been attributed to tea for about 5,000 years, since the legendary ruler Shen Nong discovered that the leaves of the plant Camellia sinensis cleansed the gut when drunk in an infusion. Early Chinese Buddhists used tea as an aid to meditation and general good health, and early traditional Chinese medical texts also point out the health-giving properties of a daily brew.
Tea (i.e. leaves from the plant Camellia sinensis, not herbal mixtures) contains antioxidant chemicals called polyphenols. Recent studies suggest that these chemicals protect tea- drinkers against serious illnesses like cancer and heart disease. Even the caffeine in tea may be somewhat beneficial.
There are three types of real tea: green, black and oolong (wulong cha). Green tea (lu cha) is the least processed of all the teas, made by quickly steaming or heating the leaves of the tea plant. Black tea, the stuff that Indians and Westerners like to guzzle, is known as 'red tea' (hong cha) in China. Prepared by exposing the leaves to air, this type of tea is dark in color and stronger in flavor because it the leaves have been oxidized—in lay-comrades terms, they have rusted. Oolong tea is partly oxidized, intensifying the flavor but retaining some of the fresh taste of green tea.
Contrary to common belief, green tea has as much caffeine as black tea, though all teas have less caffeine than coffee. A cup of strong back or red tea typically contains 40 milligrams of caffeine, compared with 60-100 milligrams in a cup of brewed coffee. While some experts claim caffeine is bad for you, others claim regular caffeine consumption helps many diseases. In a study using laboratory rats, Fung-Lung Chung of the American Health Foundation found that both green and black tea and caffeine given in drinking water protected the animals against lung cancer caused by a major carcinogen in tobacco. Just how Mr. Chung got the rats to smoke isn't explained, but the findings might explain why Deng Xiaoping and Mao Zedong—tea drinkers both—lived to ripe old age despite forty-plus a day cigarette habits.
But it is the aforementioned polyphenols that are being hailed as most beneficial to health. The bulk of evidence for tea's health benefits comes from studies in animals that were treated with amounts of tea polyphenols equivalent to what might be consumed by a regular tea drinker.
In a recent study, 18 mice were given green tea polyphenols in their drinking water, while 18 less lucky mice just had plain H20. All the animals were then injected with a substance that causes a condition like rheumatoid arthritis in people. Of the group that got the polyphenols, only eight developed arthritis; in the group that got plain water, all but one developed arthritis.
With regard to cancer, several dozen animal studies indicate that the polyphenols and related compounds in tea are protective, especially against cancers of the oral cavity and digestive tract. Tea chemicals are believed to act by preventing damage to DNA. Some cancer researchers claim that "Tea is one of the few agents that can inhibit carcinogenesis at the initiation, promotion and progression stages."
Studies in people, however, have yielded inconsistent results, in part because other factors like the heat of the tea and tobacco or alcohol use may have distorted the findings. But many researchers are finding very positive results. In a study conducted in Beijing using 59 patients with pre-cancerous mouth lesions, those treated for six months with capsules of oxidized green tea polyphenols experienced a decrease in the size of the lesions. In the untreated group, the lesions got larger. A study of more than 35,000 postmenopausal women in Iowa suggested that women who drank two or more cups of tea daily were less likely to develop cancers of the digestive tract and urinary tract. However, no protection was found against other cancers. A study of 1,330 Chinese men found a significantly lower level of serum cholesterol and triglycerides (both linked to heart disease and strokes) among those who drank more than l0 cups of green tea a day.
Unlike cocaine, butter, sugar, alcohol and nicotine, there seems to be no evidence that tea is bad for you in any way. Research results are almost all good news for tea addicts. So Mr. T, it seems that Beatrix Potter may have had it right: There's not much that can't be sorted out with a nice, hot, strong cup of tea.