Is tea worth all its recent healthy hype? Two USC researchers give an expert scoop on whether or not tea lives up to the claims of liquid salvation.
by Meghan Lewit
There’s no question about it… tea is hot. While tea has been used as an alternative medicine in China for the last several thousand years, it is only recently that the Western hemisphere started to take notice of the beverage’s potential health benefits, according to USC researchers. Now, tea is being hailed as a miracle elixir with the power to do everything from lower stress hormones and sooth the symptoms of PMS to protect against disease.
Although many of the claims are unproven, tea has been shown to reduce the risk of certain kinds of cancer, says Carol Koprowski, Ph.D., R.D., assistant professor of preventive medicine at the Keck School of Medicine of USC.
“The tea that has been studied the most is green tea,” she notes. “It’s one of the few teas out there that has been shown to have antioxidants—compounds that may protect against cell damage—and health-promoting benefits.”
Epidemiologist Anna Wu, Ph.D., professor of preventive medicine at the Keck School, is studying the relationship between green tea consumption and breast cancer risk. An earlier study about breast cancer risk among Asian-American women showed that green tea intake had a strong protective effect, while the more commonly consumed black tea had no effect at all, she says.
While both green and black teas come from the same Camellia sinensis plant native to Asia, the leaves are processed differently. Black tea leaves go through a fermentation process that strips the plant of its natural polyphenol compounds, which are believed to give the tea its antioxidant properties, Wu says.
Results from a small pilot study suggest that regular green tea drinkers had lower blood estrogen levels, while regular black tea drinkers had higher blood estrogen levels. Higher levels of estrogen are associated with breast cancer risk, Wu explains.
While green tea is gaining in popularity around the world in part due to reports of its disease fighting properties, consumption still lags far behind black tea in most cultures.
“Seventy-eight percent of the tea consumed in the world is black tea,” says Wu. “Green tea is mostly consumed in Asia.”
A life-long black tea drinker, Wu says she hasn’t given it up but now drinks at least one cup of green tea a day as well.
Some studies have also suggested that regular green tea consumption can reduce the risk of diabetes and cardiovascular disease, but the findings have been less conclusive and often contradictory, notes Koprowski.
A 2006 study in Japan found that drinking green tea might lower stroke risk, but found no evidence that it protected drinkers from cancer, the Associated Press reported. The study suggested that the popularity of green tea in Asia explained why the Japanese are less likely than Americans to die of heart disease and stroke, although the U.S. Food and Drug Administration previously said there was no credible evidence that green tea decreased cardiovascular disease risk.
In January, German scientists at the University of Berlin in Mitte reported that drinking milk with tea eliminated the protective effect against cardiovascular disease by decreasing the amount of compounds that protect against heart disease.
It’s possible that the compounds in milk interfere with antioxidant compounds in the tea, and drinking tea plain is recommended in order to get the full health benefits, says Koprowski. However, much more research is needed to understand the beverage’s effects and its potential ability to stave off disease, she adds.
Regardless of whether the benefits are as widespread as some reports claim, a few cups of either green or black tea a day is a smart addition to a diet as a replacement for high-calorie sodas and fruit drinks, notes Koprowski. Even sweetened tea has fewer calories than a can of soda.
On the flip side, consumers should be wary of teas that claim to have benefits such as weight loss or alleviating the symptoms of PMS, she says. Because tea falls under the heading of food or dietary supplement, it does not have to be approved by the Food and Drug Administration. Herbal teas that claim to be weight loss aids can put undue stress on the heart or cause dehydration, says Koprowski.
People should also be aware that some teas are a source of caffeine, although the average cup has about half the amount of caffeine as a cup of coffee.
“If you’re used to having more caffeine, tea may not give you the jolt you’re looking for,” says Koprowski. “But for people who want a hot beverage but don’t want a lot of caffeine, tea can be a nice alternative. It’s fair to say there’s no reason why you shouldn’t drink it.”
