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Green Tea Is Heart-Healthy
Green Tea May Help Keep Your Ticker Ticking
Japanese researchers find reduced risk of heart attack in
those who drink it
By Will Block
  hen Mother Nature takes a shine to something, she can be
most kind and generous. How else can one explain the marvelous properties of
Camellia sinensis, the venerable tea tree? Since time immemorial, imbibing the
humble but delightful beverage called tea has given people pleasure and
comfort—and nourishment as well (although that is not usually a major
consideration). Next to water, tea is the most popular beverage on earth.
Whether alone or at a social gathering, drinking a nice cup
of tea has a civilizing influence, infusing the spirit with a sense of peace
and tranquility. It can foster the feeling, if only for a short while, that the
world is a better place than it really is. If soccer hooligans drank tea
instead of beer, they probably wouldn’t be soccer hooligans.
Now comes news that yet
another “anti” can be added to
the already long list of “anti’s”
for green tea: anti-myocardial
infarction, or, in plain
talk,
anti-heart attack.
So tea warms our hearts, in a manner of speaking, and that
makes us better people, doesn’t it? But wait, there’s more. As we’ll see below,
tea not only warms our tickers, it actually helps keep them ticking so that we
may stay . . . alive. It’s not that we don’t value the human spirit, but it is,
after all, the welfare of our bodies that we’re most concerned with in the
pages of Life Enhancement. Take good care of your body, and your spirit will be
happy to live there.
Green Tea Has Multiple Health Benefits
Last month we saw how tea—green tea, to be precise—suffuses our
bodies with nutrients that play an important role in helping to prevent some
serious diseases.* Green tea contains chemical compounds called catechins
(pronounced cat´-eh-kins), which have remarkable powers to help stave off
diabetes and inhibit the growth of cancer cells, among other things. And when
we drink green tea, or take it as a supplement, we then contain those catechins. (Remember the “Got milk?” advertising slogan? How about one that
says, “Contain catechins?” OK, maybe that’s not quite as cat-eh-chy, but taking
green tea seriously could be a lot more beneficial for your health than
worrying about that white stuff.)
Green tea has been described by scientists as antibacterial,
antiviral, anticarcinogenic, and antimutagenic—and to that list, as we saw last
month, can be added antidiabetic. Now comes news that yet another “anti” can
be added: anti-myocardial infarction, or, in plain talk, anti-heart attack.
Japanese scientists at the National Defense Medical College in Saitama have
reported that green tea seems to confer a protective effect against the risk of
heart attack in humans. Actually, researchers in Finland had previously come
to a similar conclusion, based on a study of flavonoid intake in male smokers.
Flavonoids Are Powerful Antioxidants
Flavonoids, which are found primarily in fruits and vegetables, as well as in tea and wine, are a
broad class of compounds that are widely believed to be highly beneficial to
human health, mainly because of their powerful and varied antioxidant actions.
By neutralizing harmful free radicals that can damage vital cell components,
they protect against a variety of debilitating or fatal diseases and against
some of the effects of aging. Flavonoids thus promote better health and,
therefore, longevity.
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How Green Is Your Tea?
Why does tea have to be green to provide the health benefits
we want? Sounds like blatant discrimination against the other two colors of
tea, oolong and black.* Relax, ACLU, it’s not personal, it’s strictly science.
All true teas—green, oolong, and black—are made from the same young, tender
(and very green) tea leaves, taken only from the outermost ends of the twigs.
Where the teas differ is in the processing of the leaves.
To make green tea, the leaves are steamed before they’re
dried, and the heat inactivates certain enzymes that would destroy most of the
tea’s catechins if given the chance. That chance comes, for oolong and black
teas, in the oxidative fermentation process that gives them their distinctive
characteristics of aroma, flavor, and color, including the loss of the original
green color. (The oxidation turns the leaves brown, just as a slice of apple
oxidizes to a brown color if left to stand in the air.)
For oolong tea, the fermentation is partial, and for black
tea, it’s more or less complete. Thus oolong tea typically retains a fair
amount of catechin activity, whereas black tea typically retains very little.
And that is why, for health purposes, the unfermented green tea is much
superior to oolong or black. Green Power!
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EGCG Is Green Tea’s Ace Molecule
Among the most important classes of flavonoids are
polyphenols, and among the most beneficial of the polyphenols are the
catechins. One catechin in particular, called EGCG (for epigallocatechin
gallate), is considered by some scientists to be among the most promising
natural anticancer compounds ever discovered. As we saw in last month’s
article, EGCG is now also known to be the compound principally responsible for
green tea’s effects in enhancing insulin function, which helps control blood
sugar levels. In other words, EGCG is an antidiabetic agent. (To learn why EGCG is found mainly in green tea,
see the sidebar above.)
Why Do the Japanese Have Fewer Heart Attacks?
Here, however, we are interested in the effects of green tea
on heart disease, which is much less prevalent in Japan than in the United
States. The Japanese researchers enrolled 393 men and women (mostly in their
60s) who were having coronary angiography for suspected coronary artery disease
(CAD), based on risk factors such as hypertension, high cholesterol, and
diabetes. It turned out that 276 of them (70%) had CAD; the rest did not. Those
who did were older, predominantly men, and had lower levels of HDL (the “good
cholesterol”) and higher rates of diabetes and smoking. No surprises there.
Furthermore, 128 of those CAD patients (46%) had a history
of myocardial infarction (MI), or heart attack. (See the sidebar below.)
Compared with the CAD patients who did not have MI in their background, the MI
patients were a little younger, predominantly men, and had lower rates of
hypertension and diabetes. That may seem surprising, but consider that older
people with MI are more likely to be killed by it than younger people are, so
the MI survivors tend to be the younger, “healthier” ones, and the statistics
reflect that.
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How Do You Define CAD and MI?
In the Japanese study discussed in the accompanying article,
CAD (coronary artery disease) was defined as at least one coronary artery
having more than 50% stenosis, a constriction or narrowing of the vessel’s
inner diameter, such as that caused by the buildup of atherosclerotic plaque.
This can be determined by angiography, which is the x-ray examination of blood
vessels following the injection of a radiopaque substance into the bloodstream.
A radiopaque substance is anything that blocks the passage of x-rays, making it
visible on the film; in this case, it makes the blood inside a blood vessel
visible, and the inner diameter of the vessel can thus be measured.
MI (myocardial infarction) was confirmed in the study by the
documentation of coronary artery stenosis plus either elevated levels of
certain cardiac enzymes or certain specific diagnostic changes in the patient’s
electrocardiogram—either one being indicative of a past heart attack.
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The researchers carefully interviewed all the patients
regarding their intake of antioxidant foods and beverages (including any
significant changes in their consumption habits during the preceding five
years), hoping to find an inverse relationship with their heart disease. They
asked, among other things, how much of the following antioxidant beverages the
patients consumed daily: green tea, coffee, black tea, wine, and cocoa. Not
surprisingly for a study conducted in Japan, the overwhelming favorite was
green tea. The percentages of patients drinking one or more cups per day of
green tea and the other four beverages listed were 80%, 46%, 9%, 3%, and 2%,
respectively.
Green Tea Reduces the Risk of Heart Attack
So what did the Japanese researchers find? Between CAD
patients with and without MI, there were no significant differences in the
intakes of antioxidant foods and beverages—except for green tea. For starters,
it turned out that the percentage of those who drank less than one cup of green
tea per day, on average, was higher in CAD patients with MI (27%) than in CAD
patients without MI (14%). In other words, being a non-green-tea drinker (for
all practical purposes) was correlated with a higher risk for MI in those
patients who already had CAD.
Being a non-green-tea drinker
was correlated with a higher risk
for myocardial infarction
in those
patients who already had
coronary artery disease.
But what about those patients who did drink green tea? Well,
they had a reduced risk for MI, whether they had CAD or not. The prevalence of
MI was 29% for those who drank one to three cups per day, and 30% for those who
drank more than three cups per day (no significant difference there). For the
nondrinkers (less than one cup per day), however, the prevalence of MI was much
higher: 45%.
These results were obtained after a multivariate analysis of
the data in which the researchers were able to correct for the effects of
various traditional risk factors (age, gender, hypertension, fat and
cholesterol levels, diabetes, and smoking), and the intakes of fruits and
coffee. Curiously, the researchers found no correlation between green tea
consumption and the risk for CAD—only the risk for MI. In their own words:
In summary, we did
not find any inverse association between green tea intake and CAD in Japanese
patients. However, a green tea intake of one or more cups per day was found to
be inversely associated with MI, suggesting that green tea intake may be
related to a reduced risk of MI in Japanese patients.
Green Tea Is Good for Everyone
Does this mean that the low rate of heart attack in Japan is
caused by the high rate of green tea consumption? No, but the green tea may
well be a factor, along with many others. In any case, if you’re not Japanese,
don’t worry—green tea is probably just as good for you as it is for them. (And
it has very little caffeine, by the way, whereas black tea has quite a lot.)
Patients who drank green tea had
a reduced risk for
myocardial
infarction, whether they had
coronary artery disease or not.
Not only can green tea help prevent diabetes, it may also
help prevent a heart attack, as we have just seen. Now, diabetes is a known
risk factor for cardiovascular disease, so might there be a connection there?
Could the insulin-enhancing effect of EGCG have something to do with the
reduced risk for heart attack? We have no idea. Or could it be that green tea’s
antibacterial action in the mouth has something to do with it?4 High levels of
oral bacteria are another known risk factor for heart disease. Again, no idea.
Be Grateful for Green Tea
The real reason for green tea’s heart-healthy benefit may,
of course, be entirely unrelated to these effects. But it doesn’t matter. What
does matter is that green tea has the marvelous properties we know it has (and
who knows what may yet be discovered?), and that we can benefit from them in
numerous ways, possibly adding years to our lives. Thank you, Mother Nature!
You are too kind.
| Caution: If you have diabetes, do not take any supplement
that may affect your blood sugar levels without first consulting your
physician. Diabetes is a serious disease requiring careful professional
management. |
References
- Anderson RA, Polansky MM. Tea enhances insulin activity.
J Agric Food Chem 2002;50:7182-6.
- Hirano R, Momiyama Y, Takahashi R, Taniguchi H, Kondo K,
Nakamura H, Ohsuzu F. Comparison of green tea intake in Japanese patients with
and without angiographic coronary artery disease. Am J Cardiol 2002;Nov 15;90:1150-3.
- Hirvonen T, Pietinen P, Virtanen M, Ovaskainen ML,
Hakkinen S, Albanes D, Virtamo J. Intake of flavonols and flavones and risk of
coronary heart disease in male smokers. Epidemiology 2001;12:62-7.
- PDR for Herbal Medicines, 2nd ed. Medical Economics Co.,
Montvale, NJ, 2000, p 370.
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The Lowdown on High Tea
 You gotta love the British. Aside from a few deplorable
aberrations, such as warm beer and soccer hooligans, they’re so classy. They
have the pomp and pageantry of the royals, the wit and wisdom of the BBC, and a
sense of style and elegance that sets them apart from the rabble. And, of
course, they have “high tea,” which many of us on the left side of the Atlantic
regard with some awe as a genteel ritual, long on manners and graciousness of a
kind we have never really mastered. Our tea heritage seems to derive more from
the spirit of the Boston Tea Party than from that of a London drawing room.
But wait a minute—how high is that tea, really? Must one be
a refined society lady or gentleman to partake of this tradition without making
a fool of oneself? Is “high” really about the height of British gentility, or
could it be about the height of . . . uh, British barstools?
Oops! The secret is out: it’s barstools! That’s what the
“high” in high tea refers to. Furthermore, it’s not even so much about tea as
it is about the evening meal—and not that of the upper crust, either.
A long-ago tradition of the British working class was to
take this hearty meal (with tea, of course) sitting atop barstools in a teashop
or at a counter. And when they sat on the stools, they and their tea were,
well, high. So high tea is just a quaint old term for . . . supper. (Can you
spell “disillusionment”?)
There is a saving grace, however, and it’s called “afternoon
tea.” That’s the classy affair, elegantly served at four o’clock with scones,
crumpets, and other delicacies, and steeped in the British gentility we so
admire.
So here’s to afternoon tea—and for the sake of your health
and longevity, make it green!
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Will Block is the publisher and editorial director of Life
Enhancement magazine.
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