Green Tea for Long Life?
Japanese Study Shows Link Between Green Tea Drinkers and Lower Death Risk
More Benefits for Women?
Why do women seem to get more of a benefit from green tea than men do?
Kuriyama and colleagues note that the men in their study smoked more cigarettes than women did. And smokers, overall, got less of a benefit from green tea than nonsmokers.
But Cheng says it's related to estrogen. Green tea studies consistently show a greater effect for women than for men, he says. He suggests that green tea's active ingredients may interact with the female sex hormone estrogen to boost a heart-protective effect.
Green Tea: No Effect on Cancer
Kuriyama and colleagues found no evidence that green tea protects against cancer death.
Kuriyama says that was a surprise to him, as "abundant" evidence from animal and test-tube studies suggests that green tea ingredients fight cancer.
But he notes that the current findings are in line with other, smaller studies that find green tea has no effect on several specific kinds of cancer.
Green Tea Warnings
While it's yet to be proved that green tea really will protect you against early death, there's a lot of evidence that green tea is safe -- with two major exceptions.
Cheng warns that green tea contains vitamin K. Vitamin K affects blood clotting. People taking the blood-thinning drug Coumadin, he says, should not start drinking more green tea.
And Kuriyama warns against drinking your green tea piping hot.
"Drinking green tea at high temperature may be associated with increased risk of esophageal cancer," he says. "Therefore, I recommend that green tea should be consumed at moderate or low temperature."
What's the bottom line? For Lichtenstein, the message is to go ahead and drink green tea if you like it. But to prevent heart diseaseheart disease and strokestroke, what really works is a healthy diet and daily exercise.
Neither Kuriyama nor Cheng would disagree with that. But they both recommend green tea, too.
"I personally drink two to three cups of green tea per day," Kuriyama says. "On the basis of our study results, I would like to recommend the drinking of green tea to my friends and my family because our findings are the best evidence at present."
Cheng says green tea is much better for you than oolong tea or black tea, which lose some healthy properties during fermentation. But that's not why he drinks it.
"I drink two cups a day because I like it," Cheng says.