Those of you who listened to my radio show last Sunday heard that I was struggling with my voice. You may also have noted that I only answered text messages and took no phone calls. That’s because my ears were so congested that I had trouble hearing. I picked up some bug on a vacation at a resort down south that was pretty nasty. Decongestants didn’t do much, but hot tea was sort of comforting, so I drank and drank. Since I don’t need my ears to write, I thought a little article about tea would be appropriate at this time.
Billions of people around the world drink tea regularly. After water, it is the most widely consumed beverage in the world. Legend has it that the first cup of tea was brewed accidentally in the court of the Chinese Emperor Shen Nung almost five thousand years ago. It seems the Emperor’s drinking water was routinely boiled, and that some leaves from the burning branches under the pot drifted into the water. The adventurous Emperor drank the brew anyway and noted that it not only quenched his thirst but also lessened his desire to sleep. Of course, what was good enough for the Emperor was good enough for the populace, and tea became the most popular drink in China.
The beverage was eventually introduced into Europe in the seventeenth century, but was not an immediate success. It was expensive and, in many instances, was vilified by the clergy as a dangerous intoxicant. These denunciations sometimes took on a spectacular form. The Reverend Dr. Hales in England once demonstrated that if the tail of a suckling pig were dunked in a cup of tea, it would emerge hairless. Most people recognized the folly of this experiment, and in spite of the Reverend’s dramatic demonstrations, tea sales did not tail off.
Herbal teas aside, all tea originates from the leaves of the Camellia sinensis plant. Exactly which leaves are picked determines the eventual flavor of the beverage. Orange pekoe tea, for example, is brewed from the second leaf next to the bud, pekoe from the third. Evidently, picking tea is not an easy task. Neither is unraveling its chemical mysteries.
Like many natural products, tea contains hundreds of compounds. The most characteristic of these are often referred to as flavonoids, a subcategory of polyphenols found in many plants. A subclass of the flavonoids, the catechins, is responsible for the flavor as well as for the beneficial health effects. The extent to which these compounds are present in the final beverage depends on how the leaves are processed. To make black tea, the dried leaves are crushed to liberate enzymes that react with the catechins over a few hours to produce changes in flavor and color. This is often referred to as “fermentation.” Green tea is not fermented; it is made by first steaming the leaves to halt any enzyme activity. Oolong tea is partially fermented. The highest concentration of catechins is therefore found in green tea. Of particular interest is epigallocatechin-3-gallate. The name may twist a few tongues, but it is raising more than a few eyebrows. That’s because EGCG, as it is mercifully abbreviated, may offer significant protection against the two greatest scourges of our time, namely cancer and heart disease.
The current interest in the health benefits of tea was spurred by a Dutch study published in 1993 linking the consumption of foods high in flavonoids with a lower incidence of heart disease. Especially noteworthy was the protection that seemed to be offered by drinking four cups of tea a day. This meshed with the observation that the rate of cardiovascular disease in China, where tea is extensively consumed, is one-fifth that in the developed world. There was even a theoretical rationale for the protective effect. High blood cholesterol is, of course, known to be a risk factor for heart disease, but it is also known that the actual damage to arteries occurs when cholesterol undergoes a process known as oxidation. This process produces those highly active and potentially dangerous species everyone has heard of, the “free radicals.” It turns out that catechins are potent “antioxidants,” or free radical scavengers.
Free radicals have also been implicated in the onset of cancer. So perhaps it is not surprising to discover that lung cancer rates in Japan are lower than in North America, even though the Japanese smoke more. They drink a great deal of green tea. A Chinese study showed that people who drank more green tea had a lower incidence of cancer of the esophagus, and an American study linked long-term tea drinking with protection against pancreatic cancer.
Animal experiments also support the health benefits of tea. Rats fed cholesterol and green tea extracts had lower blood cholesterol than those not given tea. Mice given green tea in their drinking water developed fewer tumors when exposed to a carcinogen from smoke. Even skin cancer was less prevalent in mice exposed to ultraviolet light if they were given tea to drink.
Laboratory experiments confirm the antioxidant effect of tea. Free radicals chemically generated in a test tube are neutralized by tea more effectively than by the antioxidants found in fruits and vegetables. Only garlic comes close. Recently, it has even become possible to measure the ability of various substances to trap free radicals in human plasma, and tea again performed in a stellar fashion. In the lab, EGCG actually kills cultured human cancer cells without affecting normal cells. Other studies have shown that tea increases the concentration of enzymes that remove toxins from the body and impairs the activity of another enzyme, urokinase, used by cancer cells to invade neighboring cells. But of course, no population studies, no animal experiments, and no laboratory tests can prove that tea is an effective cancer preventative in people. Only human intervention studies can do that. And one such study did.
Chinese researchers followed the progress of a group of people who had been diagnosed with precancerous lesions in their mouths. Normally, a high percentage of such patients is expected to develop cancer. Half the subjects were given a mixture of green and black tea extracts to drink regularly, while the others were treated with a placebo. After six months, there was a dramatic decrease in the lesions noted in the mouths of the people who had been drinking tea. Very impressive.
I know of no study that has explored the effects of tea on congested ears. I’d like to hear from anyone who has found a benefit. I use the word “hear” loosely because I still have some trouble. So, email me at joe.schwarcz@mcgill.ca instead.
# Reprinted with permission. Dr. Schwarcz’s original article can be found on the OSS website
