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Fri March 15, 2013
The Salt

A Daily Habit Of Green Tea Or Coffee Cuts Stroke Risk

Originally published on Mon March 18, 2013 3:58 pm

Whether it's green tea that warms you up, or coffee that gives you that morning lift, a new study finds both can help cut the risk of suffering a stroke.

The study, published in the American Heart Association journal Stroke, included 82,369 men and women in Japan.

Researchers found that the more green tea a person drank, the more it reduced the risk of suffering a stroke.

"It's almost a 20 percent lower risk of stroke in the green tea drinkers" who drank four cups a day, compared with those who rarely drank green tea, explains Dr. Ralph Sacco of the University of Miami. (He's the past president of the American Heart Association, and we asked him to review the study for us.)

And with coffee, researchers found just one cup per day was also associated with about a 20 percent decreased risk of stroke during a 13-year follow-up period.

"I was still feeling rather surprised" about the findings, Dr. Yoshihiro Kokubo, the study's lead author, tells The Salt in an email. Kokubo is a researcher at the Department of Preventive Cardiology, National Cerebra and Cardiovascular Center in Osaka, Japan.

Kokubo says that green tea contains compounds known as catechins, which help regulate blood pressure and help improve blood flow. The compounds also seem to promote an anti-inflammatory effect. Kokubo says coffee, which contains caffeine and compounds known as quinides, likely influences our health through different mechanisms.

It's not just the Japanese who seem to benefit from drinking coffee and green tea. Over the past few years, researchers in the U.S. have documented similar reductions in heart disease risk among Americans.

"The accumulating evidence from a variety of studies is suggesting that green tea and coffee may be protective," says Sacco.

And, in addition, recent studies have linked a regular coffee habit to a range of benefits — from a reduced risk of Type 2 diabetes to a protective effect against Parkinson's disease.

It's interesting to note how much the thinking about caffeine and coffee has changed.

In the 1980s, surveys found that many Americans were trying to avoid it; caffeine was thought to be harmful, even at moderate doses.

One reason? Meir Stampfer of the Harvard School of Public Health says back then, coffee drinkers also tended to be heavy smokers. And in early studies, it was very tough to disentangle the two habits.

"So it made coffee look bad in terms of health outcomes," says Stampfer.

But as newer studies began to separate out the effects of coffee and tea, a new picture emerged suggesting benefits, not risks.

Researchers say there's still a lot to learn here — they haven't nailed down all the mechanisms by which coffee and tea influence our health. Nor have they ruled out that it may be other lifestyle habits among coffee and tea drinkers that's leading to the reduced risk of disease.

And experts say when it comes to preventing strokes and heart attacks, no food or drink is a magic bullet. It's our overall patterns of eating and exercise that are important.

"It's a whole lifestyle approach, and we need to remember that," says Sacco.

So if you are already in the habit of drinking coffee or green tea, this study is one more bit of evidence that you can go ahead and enjoy it.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

RENEE MONTAGNE, HOST:

And here's some good news for those of us who live for that morning coffee, Steve - or, all right, also green tea. A new study of 82,000 men and women in Japan published in the medical journal Stroke found those in the habit of drinking green tea or coffee were significantly less likely to have a stroke. NPR's Allison Aubrey has more.

ALLISON AUBREY, BYLINE: The striking thing about this new study investigating coffee and tea consumption, is not that researchers found an association with less heart disease, it's the extent to which the habit seemed to protect people. Let's start with green tea. Physician Ralph Sacco, the past president of the American Heart Association, says in this study the more green tea a person drank the more it reduced the risk of suffering a stroke.

DR. RAPLH SACCO: It's almost a 20 percent lower risk of stroke in the green tea drinkers.

AUBREY: Who drank four cups a day compared to those who rarely drank green tea. And with coffee, researchers found just one cup per day was also associated with about a 20 percent decreased risk of stroke within the next decade.

SACCO: It's a pretty important effect. It's a large study, so larger study more you can detect effects like this.

AUBREY: Now, Sacco says it's not just the Japanese who seem to benefit. Over the last few years, researchers in the U.S. have documented similar reductions in heart disease risk among Americans.

SACCO: The more accumulating evidence from a variety of studies, suggesting that green tea and coffee may be protective.

AUBREY: Studies suggest a coffee habit may also cut the risk of Parkinson's and Type 2 diabetes. Now, it's interesting to note that not long ago there was completely different thinking about coffee. In the 1980s many Americans were trying to avoid it. Caffeine was thought to be harmful, even at moderate doses. Harvard's Meir Stampfer says one reason for this is that back then coffee drinkers also tended to be heavy smokers.

And in early studies it was very tough to disentangle the two habits.

MEIR STAMPFER: So it made coffee look bad in terms of health outcomes.

AUBREY: As newer studies began to separate out the effects of coffee and tea, a new picture emerged: one suggesting benefits, not risks. Now, the Heart Association's Ralph Sacco says there's still a lot to learn here. Researchers haven't nailed down all the mechanisms by which coffee and tea influence our health.

And he says when it comes to preventing strokes and heart attacks, no one food or drink is a magic bullet. It's our overall patterns of eating and exercise that are important.

SACCO: It's really a whole lifestyle approach, and we need to remember that.

AUBREY: So if you are already in the habit drinking coffee or green tea, this study is one more bit of evidence that you can go ahead and enjoy it. Allison Aubrey NPR News.

MONTAGNE: This is MORNING EDITION from NPR News, made possible by this cup of coffee. I'm Renée Montagne.

STEVE INSKEEP, HOST:

And I'm Steve Inskeep. Transcript provided by NPR, Copyright NPR.