I probably never told you that once I spent several weeks in Japan. I had a splendid time there because (for one thing) in Japan I am Not Short, so all the chairs were comfortable. But also, I noticed green tea stuff everywhere. Not only is there green tea that you drink (hot or cold, with or without a meditative ceremony), but there's green tea ice cream and green tea candy and green tea soda and green tea cosmetics and well there are whole stores of it (and
most are painted this lurid shade of seafoam.) (They also have a brand of soda called "Pocari Sweat," which I did not try.) Someone told me that in Japan green tea is revered as a powerful cancer preventive. At the time, I remember thinking this was quaint. (This was years ago. I was stupid.) The ice cream was pretty good, and that was about all. I was not aware that in countries where people drink a lot of green tea there really is less cancer.
And now suddenly green tea is trendy. I see people get all excited over stuff that looks to me like sticks in water, and patients are asking me about whether they should take the extract and, well, I do love the stuff that comes along with my sushi. But what inspired me to actually Learn Something about green tea was this: Japanese scientists have found that some component of green tea seems to block the effects of dioxin. Dioxin is a horrible pollutant that
causes cancer, neurologic disease, immune dysfunction, and reproductive disorders (for starters). It's a byproduct of incineration and also of the bleaching of paper. In Maine, we have a real problem with environmental dioxin, so anything that can help counteract it is appealing.
Tea contains substances called catechins special forms of antioxidants* that protect your cells (specifically, the DNA inside of each of your cells) from damage caused by life as we know it metabolism, pollution, radiation, etc. We used to think that most green tea effects were due to the antioxidant properties, but now it looks like it can also block toxic liver enzymes (particularly one which causes lung cancer in
smokers and gastrointestinal cancers in people who eat charred meat) and help you detoxify carcinogens. This is a whole new feature, so pay attention! I'm telling you, those quaint Japanese were on to something.
So, why green tea and not black? And what's "white tea" and why is it so expensive? So, here's the deal. All four main kinds of tea are leaves of the camellia sinensis plant. The color of the tea reflects whether, and if so how long, the dried leaves were allowed to ferment. White and green tea aren't fermented; oolong tea is fermented a little bit; black tea is fermented a lot. The longer the tea is fermented, the less catechins it has. The youngest tenderest
leaves have the most catechins in them and that's what white tea is made from (and of course since it is young and tender it is precious.) For green tea, mature leaves are used but the tea is very minimally processed (that's why it's still green!) before it's dried and packaged for drinking. Black and oolong tea have less antioxidant capacity (but still more than coffee.) The more antioxidant activity in tea, the less caffeine, just FYI.
So how much green tea do you have to drink, anyway? Some research projects have people drink eight cups daily; in China and Japan, typically people drink ten to twenty cups a day! Though one study showed that tea catechins did prevent premalignant prostate cancer lesions from progressing, you'd have to drink forty cups of green tea a day to get what they used in the study. For an ordinary person, a reasonable consumption of green tea is two to four cups a day.
Use organic tea; teas from China and India tend to be heavily sprayed with pesticides. If you're after decaffeinated tea, look for brands that are water or carbon dioxide processed.
There is, of course, more to green tea than the dioxin and cancer thing. Green tea catechins also prevent stroke, strengthen bones and blood vessels, enhance immune function, reduce inflammation, and stabilize blood sugar. In principle, green tea should be useful in the prevention of heart disease and cancer, but studies done on people take a while and are not yet compelling. Many scientists believe there is potential there, though, and there are several large
trials going on as I write.
Green tea catechin supplements are available but interestingly, it looks like they aren't as powerful as whole leaf tea. We don't seem to be smart enough to be able to figure out all the things that are in plants and how they work together and then copy it. (Ditto with breastmilk and infant formula but I digress.) We have known for a while that the antioxidants present in fruits and vegetables are important for health, and yet when we run studies where people
are given pills of what we think are the active ingredients in those foods, we don't see what we expected. There is something in Mother Nature that wants you to have real food and perhaps a nice relaxing cup of tea and not pills. (Are you surprised?)
*I like to think about antioxidants and how they protect us from oxidative damage this way: Imagine you are a sweet young shrub and it's spring and you are just starting to unfurl your new baby leaves and you are out in a field, toasting in the sun. Sun-toasting is a prime source of oxidative damage to cells and the DNA living inside them just look at the skin of an old person who's been outdoors a lot, and remember about
melanoma. Plants can't run indoors to protect their tender, newly-unfurled little leaves (or their precious seed packages "fruit") from toasting in the sun, so what do they do? They make their own anti-oxidant molecules and they pack them into those leaves and seed packages natural SPF. Most of the antioxidants we want come from plants plants who learned to make them so they wouldn't get plant sunburn. The antioxidants are often packaged in molecules of brightly
colored pigments to make them pretty; you can think of the pigments as kind of how plants get "tan." So, eat your fruits and vegetables they're all part of the plan.