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Tea: Does It Deliver Health Benefits?
by Roberta Greenwood

Pick up almost any magazine these days and you’ll find an article touting the health benefits of adding tea (primarily green or black) to your diet. Titles such as “Green Tea’s Healthy Dividends” or “Green Tea May Lower Risk of Lung Cancer” capture our attention and send many of us to our local markets in search of the often mild, sometimes grassy brew. Still an uncharacteristic choice for most Americans, throughout Asia green tea is a staple of the diet, with estimates of typical consumption ranging from three to four cups per day. With lower than expected rates of heart disease and cancer, even in a culture that supports a higher rate of smoking, researchers began to test whether tea consumption was a missing link to optimum health.

Hundreds of international studies conducted over the past 10 years, published by respected health researchers and widely reported, suggested that drinking tea (green or black) delivered a variety of health benefits, ranging from cancer prevention to better digestion.

However, in a July 2005 report, the U.S. Food and Drug Administration concluded that current scientific evidence doesn’t support the earlier tests – a conclusion that disappointed wellness-minded tea drinkers. Now, new to this mix of seemingly conflicting information is a recent study in Japan, funded by the Japanese government and published in the September issue of the Journal of the American Medical Association, which suggests that tea consumption might lower your risk of stroke but not of cancer.

Judy Simon MS, RD, and a clinical nutritionist at the University of Washington Medical Center, agrees that the recent study holds promise. “There have been many studies; the evidence seems strongest so far in the area of cardiovascular disease prevention. Some of the cancer studies results have been contradictory.” So, when it comes to drinking tea, what’s the best advice for a health-conscious woman?

According to Mark Kestin, PhD, MPH, professor of nutrition and exercise science at Bastyr University and adjunct associate professor at the University of Washington, “tantalizing” evidence exists that tea (green and black) may aid in the prevention of heart disease, but studies in humans have provided very inconsistent results. “There’s really not a ‘yes or no’ answer,” Kestin explains. “What does proof mean? Some epidemiological studies such as the one in Japan suggest several health benefits can be derived from the consumption of tea. We’ve seen mixed short-term results in human studies but a substantial clinical trial hasn’t been done.”

Kestin points out that many of the studies which concluded tea offered a wide array of health benefits were conducted on animals or in “test-tube” trials. While not disputing the findings, Kestin suggests we need more evidence to support the claims that tea consumption can provide health benefits to the general population. The Japanese study, while including over 40,000 subjects, “pointed you in a direction,” says Alice Lichtenstein of the American Heart Association, but still isn’t conclusive. Many of its healthy subjects tended to eat more fruits and vegetables than average and were less overweight than Americans – two facts that might also reduce the risks of cardiovascular disease, thus skewing the results.

Kestin explains that compounds found in green and black tea (polyphenols or catechins) provide antioxidant properties which are beneficial to the human body. These compounds differ in the type of tea that’s consumed, with green tea having more than three times the number of these compounds compared to black. “The less commercial processing the tea undergoes, the higher level of the polyphenols,” says Kestin. While all tea comes from the same plant, processing differs: white tea (fairly rare and less often consumed than green or black tea) is picked early with immature leaves. Black tea is allowed to ferment and oxidize, while green tea is less processed, which is believed to increase its antioxidant properties.

As Kestin points out, even the brewing of the tea is an important step to delivering health benefits. “There are so many variables – how long you steep the tea before drinking it, do you use boiling water?” he points out. “All these factors affect the benefits derived by adding tea to your diet.” Most studies which promote tea consumption suggest that heavy tea drinking – more than four cups per day – is necessary to obtain optimum health benefits.

Women participants in the Japanese study who drank more than five cups of green tea daily lowered their risk of cardiovascular disease by 31 percent and clot-related strokes by 62 percent – an improvement that’s significant considering stroke is the third most common killer of women in the U.S.

With all the seemingly good news, can tea consumption contribute any negative side effects? Again, Kestin answers, that depends. “While lower than coffee, tea still contains caffeine; some people may need to consider that before adding several cups of tea to their daily diet,” he suggests. Simon adds that green tea can interact with many drugs such as certain antibiotics, beta blockers, blood thinners, and several anti-psychotic drugs. “If you’re taking medications, it would be wise to check with your physician or pharmacist,” she advises. Research also indicates high tea consumption can reduce the body’s ability to absorb iron – a problem that Kestin explains can be avoided by drinking tea separately from meals.

In the end, as with so many health considerations, adding tea to your nutritional strategy may be appealing on many levels. A 2005 study conducted by the American Institute for Cancer Research indicated that only 15 percent of Americans drink green tea daily – in comparison with a staggering 62 percent who say they consume soft drinks on a daily basis. Certainly, substituting a water-based drink for sugar-based drinks is a healthy alternative Kestin reasons. “In principle, if a person wants something to drink that’s better than many other beverages, tea may be it,” he laughs. “Just don’t lace it up with milk and drink it with cookies!”

Roberta Greenwood is a writer and environmental activist who contributes frequently to Seattle Woman.

©2006 Caliope Publishing Company