Great discovery stories often sound a bit unlikely: Benjamin Franklin experimenting with electricity by fiddling with a kite and a key in a lightning storm; Isaac Newton idling under a fruit tree and suddenly having his theory of gravity knocked loose by a falling apple.
Then there’s the legend of Shen Nung, the great Chinese emperor and healer, who was boiling water one day circa 2700 BC when a few leaves from a nearby bush drifted into his pot. The emperor drank the water and immediately felt refreshed, alert and cleansed. Henceforth, he proclaimed that all his people should partake of the hot drink that would become known as “tea.”
In the eighth century AD, the first seeds of the tea plant were brought to Japan from China by returning Buddhist monks, who, it is said, originally used tea to keep from falling asleep during meditation. By the 10th century, bricks of compressed tea had become a form of currency used throughout northeast and central Asia. But it wasn’t until the early 1600s that tea made its way to Europe, brought by Dutch traders.
By the late 17th century, tea had reached the colonial settlements that would become the United States. Only in the mid-1990s, however, did Western medicine begin rediscovering the health benefits of tea.
During the past decade or so, study after study has confirmed what Shen Nung intuited millennia ago: Tea has both preventative and curative health properties. This widely available foodstuff is antioxidant, antiviral, antibacterial and anti-inflammatory. It is without calories, fat or sugars. What’s more, it tastes great.
“How many times do you find something that’s almost decadent in its sensory appeal, but at the same time is good for you?” asks Bill Waddington, owner of TeaSource, a Twin Cities–based tea importer and retailer with national distribution. “I don’t know of a single other instance. And I think it’s that unique combination of qualities that has driven the recent and dramatic increase in interest around tea.”
From Leaf to Lab
Tea is not what many people think. During the past 30 years, the term has expanded to become generic, so it is used to describe any drink in which hot water is poured over leaves, stems, flowers or seeds. We hear talk of “herbal tea” or “red tea,” referring to concoctions made from an array of plants, none of which are really tea.
True tea comes from the Camellia sinensis bush, an evergreen perennial that thrives in the subtropics and highland tropical regions of the world. Today, there are more than 3,000 varieties of Shen Nung’s magical elixir, but they can be divided into just five basic types: black, green, oolong, white and pu-erh.
All of these contain polyphenols, including flavonoids and catechins. These active plant molecules, also found in fruits, vegetables and red wine, have antioxidant properties – meaning they destroy free radicals and inhibit cell mutation. But beyond this, the science surrounding tea is somewhat fuzzy. Researchers are not certain exactly how or why polyphenols have such a globally positive effect on the body. But numerous studies prove that they do.
Homeopaths and practitioners of Chinese medicine have long advocated the use of tea as part of a basic healthcare regimen. But physicians practicing Western medicine remained skeptical until about a decade ago, when anecdotal reports began to surface indicating that certain kinds of cancer were far less prevalent in cultures where tea drinking was the norm.
Stomach cancer, for example, is one of the fastest-growing types of cancer worldwide, and researchers have spent years looking for clues as to why certain groups of people seem particularly susceptible. In 1995, interviews with 133 stomach cancer patients and 433 healthy controls in a Chinese hospital in the Jiangsu province showed that the disease was associated strongly with smoking and heavy alcohol consumption. But it also revealed, even adjusting for these other lifestyle factors, that green-tea drinkers were at a 48 percent reduced risk for stomach cancer.
In 2003, a study of 3,400 adults in Saudi Arabia, a country where tea is nearly as popular as it is in China, found that those who drank more than six cups per day had a 50 percent lower rate of coronary heart disease than non–tea drinkers.
As Good As Green?
The media focus on green tea as the most beneficial of the five varieties no doubt stems from the fact that so many of the early reports came out of countries in the Far East, where people tend to prefer it. But once formal studies were launched to examine the effects of black tea, which accounts for 95 percent of the tea consumed in the United States and Canada, it was discovered that while the catechin content is lower in black tea (making it, perhaps, somewhat less effective in combating some virulent types of cancer), the higher level of substances known as theaflavins and thearubigins produced a variety of other healthful results.
“The marketing folks always get out ahead of the research,” says Steven Pratt, MD, coauthor with Kathy Matthews of SuperFoods Rx (William Morrow, 2004) and the forthcoming SuperFoods HealthStyle. “We have a lot of data on green tea, but it’s probably good to have some of each kind of tea in your diet.”
Indeed, following the first wave of articles noting the health discrepancies between tea drinkers and non–tea drinkers, studies examining the effects of tea on particular medical conditions proliferated. Among them:
- The Linus Pauling Institute at Oregon State University found, in a study published in the journal Carcinogenesis in 2003, that routine consumption of green or white tea in combination with NSAIDs (non-steroidal anti-inflammatory drugs, such as aspirin) may help prevent colon cancer in mice.
- A 1999 study from Case Western Reserve University showed that green tea reduced the incidence and severity of collagen-induced arthritis (similar to rheumatoid arthritis) in mice.
- Scientists at the U.S. Department of Agriculture (USDA) found in 2002 that the addition of black, oolong and green teas to the fat cells of rats increased insulin activity 15-fold, potentially preventing or treating diabetes.
- A study of 1,900 heart attack patients published in Circulation: The Journal of the American Heart Association in 2002 stated that heavy tea drinkers (those who drank more than 14 cups a week of caffeinated black tea) had 29 percent fewer cardiovascular deaths than non–tea drinkers, and even moderate tea drinkers (consuming fewer than 14 cups per week) had a 21 percent lower risk of death. ”We know that 2 grams of tea leaves taken three times per day is at least preventative [against certain types of cancer],” says Qing-Yi Lu, an assistant research professor in the Department of Medicine at University of California, Los Angeles, who is studying the health properties of tea. “We are doing some studies now to see if it’s also therapeutic for people who already have cancer. But tea’s cancer-fighting activity has been known for some time, and in addition, it’s antibacterial and antimicrobial. So, generally, it’s just very good for you. I believe we will prove that all tea is healthy.”
Premium vs. Powdered
Nearly 4,000 years of evidence suggests that if you drink tea – any kind you like – you will enjoy better health. There are only a few caveats. Air, light, moisture and excessive heat all tend to degrade tea’s flavor as well as its nutritive powers. Because bagged tea can go stale more quickly than loose-leaf tea (it has more surface area to be exposed to the air), some sticklers steer clear of it in the interest of maximizing health benefits. But if bagged tea is stored properly and consumed while still fresh, all other quality factors being equal, the health difference is so minimal that most experts suggest you make the choice based entirely upon convenience and preference.
Yet nutritional quality can vary significantly by brand and product. A 2002 Reuters Health analysis of the level of catechins (a type of antioxidant) in commercially marketed teas found vast differences among brands: Celestial Seasonings Green Tea had 217 milligrams per cup, Lipton Green Tea came in at 201 milligrams, and Bigelow Darjeeling Blend (a black tea) weighed in at 164 milligrams. In contrast, the catechin count for Stash Premium Green Tea Decaf was 53 milligrams, 46 milligrams for Twinings Earl Grey, 38 milligrams for Bigelow’s Constant Comment, and a mere 10 milligrams for Bigelow’s Constant Comment Decaf.
Perhaps most disturbing is the fact that the same Reuters survey found that the two bottled tea drinks studied – Lipton Lemon Iced Tea and Snapple Peach Iced Tea – had no measurable catechin content at all. The “tea” taste is often a reduced or concentrated flavoring added to water, along with sugar or artificial sweeteners. “They did not contain any actual tea components,” Lu confirms. “They were just flavored like tea.”
According to research conducted by the USDA, powdered iced-tea mixes that were tested for catechin content generally fell into a middle ground between brewed tea and ready-to-drink beverages, containing small but significant levels. But even brewed tea, prepared using high-quality loose leaves, begins to lose its nutritive content an hour or so after it is brewed.
Prior to being brewed, though, most tea is surprisingly robust. While it may lose miniscule amounts of its polyphenols over time, good quality tea, when stored properly, will retain the bulk of its flavor and healthful properties for up to a year.
Keep loose-leaf tea in an airtight container, away from heat, moisture and light. The same treatment applies for tea bags not already packaged in airtight envelopes. Tea leaves should not be frozen or refrigerated.
The one warning that has been issued regarding tea has to do not with the plant itself, but with supplements made from tea extract. Whereas some studies have found them to be effective in preventing disease (and a boon to those who don’t care for the taste of tea), massive doses of tea extract have been shown to cause paradoxical results – sometimes causing existing cancers to spread. And Pratt and other researchers point out that there may be elements we don’t know about that are lost in the conversion from leaf to pill.
Tea for Tomorrow
We consistently relearn history’s lessons. What Shen Nung discovered in 2700 BC has been reviewed, subjected to the scrutiny of modern medicine and emphatically restated in today’s terms. Tea is, without question, a nearly universal tonic.
In addition to the proven effects of tea, there are many other properties about which the medical community has only begun to speculate. After noting that participants in unrelated health studies also lost weight while drinking significant amounts of tea, some researchers began looking into the drink’s slimming properties. While it’s too early to recommend, say, lapsang souchong as a dietary supplement, there is preliminary evidence that tea does have a mild thermogenic (calorie-burning) effect.
Meanwhile, dermatologists are hoping tea may prove to be as effective a topical treatment as it is an orally administered one. The antioxidants found in tea and other foods may help forestall the wrinkles and discoloration associated with sun damage and aging. Pratt says simply drinking tea goes a long way to help nourish skin cells, but other applications may prove equally beneficial.
“I’m not saying everyone should take a daily bath in hot tea,” Pratt explains. “But then again, that might work. With tea, it seems like you just can’t go wrong.”
Ann Bauer is a Minneapolis-based author and food editor at Minnesota Monthly.