A large epidemiological (population-based) study in Japan has found a significant reduction in the risk of death - especially deaths due to strokes - among people who drank five cups of green tea per day. However, the same study surprisingly found that green tea had no impact on the risk of dying of cancer. The Ohsaki National Health Insurance Cohort Study, published in the Journal of the American Medical Association in September, 2006, was begun in 1994. It eventually involved over 40,000 Japanese adults who had no prior history of stroke, coronary heart disease, or cancer. Participants were monitored for up to 11 years, during which time deaths attributable directly to cancer (cause-specific mortality), and deaths from all causes (all-cause mortality) were carefully recorded.

In the follow-up period, a total 4,209 of the participants who could be traced had died, with 892 participants dying of cardiovascular disease while 1,134 died of cancer.

The more green tea participants drank, the less their chance of dying of any cause, and particularly of cardiovascular diseases (including heart attacks and strokes). The effect of green tea in preventing death from any cause was stronger in women than in men. In men there was a 7 percent reduction in risk of death for those who drank just 1 to 2 cups of green tea per day; 5 percent for those who drank 3 to 4 cups; and 12 percent for those who drank five cups or more per day. The corresponding data for women were 2 percent reduction for those who drank 1 to 2 cups; 18 percent for those who had 3 to 4 cups; and a large 23 percent reduction in risk of death for those who drank 5 cups or more daily.

The reduction in death from cardiovascular disease was also strongest in women, with a 31 percent reduction in strokes among women who drank the highest amount of green tea.

Somewhat surprisingly, given the positive findings of several previous studies, this study found no significant reduction in death due to cancer for any level of green tea consumption. However, I would not rule out the possibility that future studies will show that green tea is indeed associated with a reduced risk of some forms of cancer in other populations. (The Japanese already have low rates of most cancers, and so this effect may show up more clearly in populations with higher rates of the disease, such as in the West.)

Green tea is made from the dried leaves of the shrub Camellia sinensis, but unlike black tea, it is unfermented. Green tea is inexpensive, readily available and comes in a number of distinctive varieties. The easiest way to consume five cups of green tea per day is to make it one's main daily beverage, substituting it for black tea, coffee or soft drinks. Some people find that by comparison to their customary morning coffee, green tea is rather weak. While varieties such as jasmine tea are indeed quite delicate, others pack a powerful punch - Chinese "gunpowder" green tea, for example. Two excellent varieties are Temple of Heaven Gunpowder and Pinhead Gunpowder. These come from Zhejiang province in China.

Gunpowder tea takes its picturesque name from the fact that the grey-green leaves come tightly rolled into pellets, but "explode," unfurling into their original long, flat shape when they are steeped in hot water.

In buying, look for pellets that appear shiny, indicating that the tea is fresh. Ceylonese and Formosan (Taiwanese) gunpowder varieties are widely available. Try buying and preparing green tea in leaf form rather than in individual tea bags. Tea bags, while convenient, often contain the lowest grades of powdered tea, the leavings of tea manufacturing.

It is sometimes said that the best results are obtained by adding one teaspoon of tea per person and "one for the pot." I personally find this to produce an excessively strong brew. In any case, the leaves should be steeped in hot (although not boiling) water, and the tea should be allowed to brew between four and six minutes. (Again, you may need to experiment to find the right brewing time for yourself.) It is best to put the loose tea into a sachet or tea ball that is large enough to allow the leaves to expand and yield up their flavor. You can then remove the container before the tea becomes overpoweringly strong or bitter. If you are bothered by the effects of caffeine you can find naturally decaffeinated brands of green tea, although the selection is somewhat more restricted and the taste not as full-bodied.

One can order a variety of interesting-sounding forms of green tea over the Internet, many of them organically grown. The cost is usually around $20 to $25 per pound. At Amazon.com, however, I found one a brand of loose gunpowder tea selling for $28.73 per kilogram, including shipping! That's a lot of tea - and a lot of heart-healthy ingredients - for relatively little money.

IN THE MAILBAG

We continue to receive many emails on the subject of our newsletter's recent shift of focus to one of prevention. While our readers seem united in agreeing that prevention is important, the majority of those who have written to us express a strong preference for more treatment-oriented content.

Here are some examples:

"While I wholeheartedly endorse the idea of overall wellness, especially in the cancer community, I am concerned that the information related to treatment and research into new treatments will fall by the wayside….I find your work and information irreplaceable and would hate to have to find it on my own elsewhere."

"I know that your information on new treatments, questionable research, and informative data have been of benefit to many cancer patients and their families. My hope is that you will continue to address that need as well as provide others with ways to reduce their risk for the various cancers."

"I respect your research, knowledge, and fearless reporting. I will continue to read whatever you think is important to share. What I do think is that wellness topics are relatively easy to access. We who are surviving cancer, while needing wellness info, also need someone who is more specific about the latest cancer information. We would like to know if there are things above the normal wellness ideas that can help us keep cancer at bay."

We are grateful to all those who have taken the time to write to us. We hope our readers will continue to share their thoughts with us on this (and other) subjects.

--Ralph W. Moss, Ph.D.

References:

Kuriyama S, Shimazu T, Ohmori K, Kikuchi N, Nakaya N, Nishino Y, Tsubono Y, Tsuji I. Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan: the Ohsaki study. JAMA. 2006 Sep 13;296(10):1255-65.