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What Is It
The traditional process that yields green tea is simple: The
leaves from the tea plant are first steamed, then rolled and
dried. The steaming kills enzymes that would otherwise ferment
the leaves. With other types of tea, the leaves are allowed
to ferment either partially (for oolong tea) or fully (for
black tea). The lack of fermentation, however, gives green
tea its unique flavor and, more important, preserves virtually
all of the naturally present polyphenols (strong antioxidants that can protect against cell damage). Other substances in
green tea that also may be beneficial are fluoride, catechins,
and tannins.
What Does It Do
Green tea possesses compounds that may provide powerful protection
against several cancers and, possibly, heart disease. Studies
indicate that it also fights infection and promotes longevity.
Common Uses
• May help prevent cancer.
• Protects against heart disease.
• Inhibits tooth decay.
• Promotes longevity.
Prevention
The rate of certain types of cancer is lower among people
who drink green tea. In one large-scale study, researchers
found that Chinese men and women who drank green tea as seldom
as once a week for six months had lower rates of rectal, pancreatic,
and possibly colon cancer that those who rarely or never drank
it. In women, the risk of rectal and pancreatic cancer way
nearly cut in half. Preliminary research suggest that green
tea may also fight breast, stomach, and skin cancer.
Studies investigating how green tea might guard against cancer
have pointed to the potency of its main antioxidant, a polyphenol
dubbed EGCG (for epigallocatechin-gallate). Some scientists
believe EGCG may be one of the most effective anticancer compounds
ever discovered, protecting cells from damage and strengthening
the body's own production of antioxidant enzymes. According
to a study from Ohio's Case Western Reserve University, EGCG
seems to signal cancer cells to stop reproducing by stimulating
a natural process of programmed cell death called apoptosis.
Remarkably, EGCG does not harm healthy cells. In addition,
research at the Medical College of Ohio indicates that EGCG
inhibits the production of urokinase, an enzyme that cancer
cells need in order to grow. In animals, blocking urokinase
shrinks tumors, and sometimes causes cancer to go into complete
remission.
Additional Benefits
The antioxidant effect of green tea's polyphenols may also
help protect the heart. In test-tube studies, these compounds
appeared to suppress the damage to LDL cholesterol, thought
to be an initial step in the buildup of plaque in the arteries.
A Japanese study of 1,371 men linked daily green tea consumption
to the prevention of heart disease. In addition, green tea
contains fluoride, which may help protect against tooth decay,
and provides an overall antibacterial effect.
How To Take It
Dosage: You can get the benefits of green tea either
by taking green tea capsules or tablets, or by drinking several
cups of the brew each day. Your aim should be to get 240 to
320 mg of polyphenols.
When using supplements, buy those standardized to contain
at least 50% polyphenols. At this concentration, two 250 mg
supplements would provide 250 mg of polyphenols. Studies show
that four cups of freshly brewed green tea also supply a recommended
amount of polyphenols.
Guidelines For Use: Take green tea supplements
at meals with a full glass of water. Drink freshly brewed
green tea on its own or with meals. To make tea, use 1 teaspoon
of green tea leaves per cup of very hot water. Let brew steep
for three to five minutes; then strain and drink it.
Possible Side Effects
Green tea is very safe, both as a supplement and as a beverage.
People who are sensitive to caffeine, however, may not want
to drink too much green tea, because each cup contains about
40 mg of caffeine. (Indeed, for this reason, pregnant women
and those who are breast-feeding should limit their consumption
to two cups a day.) Green tea supplements, however, have very
little caffeine. The recommended dose of green tea supplements
provides the same amount of polyphenols as four cups of green
tea, but generally contains only 5 to 6 mg of caffeine.
Latest Findings
According to researchers at the University of Kansas, green
tea's main antioxidant (EGCG) is 100 times more powerful than
vitamin C and 25 times more potent than vitamin E in protecting
DNA from the kind of damage thought to increase cancer risk.
Facts and Tips
• Green tea leaves contain hefty amounts of vitamin
K, but a cup of brewed tea or green tea supplements have virtually
none. This means that people taking anticoagulant drugs for
heart disease (who may have been told to avoid large servings
of food rich in vitamin K because of the vitamin's influence
on blood clotting) can enjoy green tea with no fear of side
effects.
• Drinking boiling hot green tea can damage your throat
and esophagus and may over time increase your cancer risk.
Try the traditional Asian method; Heat cold water until just
before it boils (or boil it and let it cool for a few minutes),
then pour the hot-but-not-boiling water over the tea leaves.
This method also helps accent the delicate flavor of green
tea.
• Imported from China, gunpowder tea is simply green
tea presented in tiny pellets resembling gunpowder. When placed
in hot water, the leaves slowly unfold.
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