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You've heard about green
tea's health benefits. Read the details here, reprinted from
an article in Tea Magazine.
ACCORDING TO A SEATTLE market-research
firm, the Sage Group, in the five years between 1990 and 1995,
tea sales in America quadrupled to four billion dollars
a year. Tea is a drink whose time has come — again.
In the American colonies, tea was the most
popular beverage until England's efforts to monopolize the tea
trade, undercut American tradesmen, and capitalize on tea taxes
turned the colonists against it. Besides throwing British tea
into the Boston Harbor, the Americans expressed their rebellion
by switching to a thicker, more bitter source of caffeine: coffee.
But the Tea Tax no longer exists, and there are good reasons
to switch back — not political this time, but scientific.
For years, studies in China and Japan have
shown that the folklore about tea does contain some truth —
it does promote longer life. In lung-cancer experiments with
rats, the rats drinking green tea had only half the cancer rate
as the non-tea-drinking rats. In other animal experiments, green
tea was found to protect against colon cancer, skin cancer, stomach
cancer, and breast cancer.
Japanese smokers have only half the lung
cancer rate as American smokers. In areas of Japan where the
most tea is drunk, the rate of stomach cancer (a big killer in
Japan) is the lowest. In a study of 6000 Japanese women, those
who drank five cups or more of green tea per day cut their risk
of strokes by 50%.
GREEN EAST VERSUS BLACK WEST
In the West, we've been slow to study tea
because, even with the increase in the popularity of tea, merchants
still sell four times as much coffee. In addition, the studies
emanating from Asia are about green tea, and Westerners
customarily drink black tea.
Does black tea have the same health-promoting
effect? Zhi-Yuan Wang of Rutgers University wanted to find out.
He gave mice some carcinogens that normally cause skin tumors.
A fourth of his mice were given green tea, a fourth got black
tea, another fourth got decaffeinated black, and the last fourth
got plain water. Sure enough, the green-tea-drinking mice developed
70% fewer tumors than the water drinkers. SEVENTY PERCENT
FEWER! These are the kinds of findings that have awakened
so much interest in tea. The numbers are big.
There are a lot of things people can do
to improve their health, but usually the effect of any one of
them is relatively small. Tea is different. For something so
easy and pleasant to do, it is startling how great a difference
it can make. The good news for us black tea lovers is the the
black-tea-drinking mice also had 70% fewer tumors than
the water drinkers. The decaf-tea drinkers had 60% fewer tumors
— still a good showing.
RESEARCH ACCELERATION
Many studies are now being done in the
West. Not only does tea reduce the rate of the cancers already
mentioned, but it lowers the incidence of esophageal and liver
cancers, too — also by dramatic amounts. And there is even
more good news: tea lowers the risk of heart disease.
The two deadliest diseases for Americans
are cancer and heart disease, and here is one substance —
a substance that is easily available, inexpensive, and contains
no calories — that lowers the incidence of both,
and by a large margin!
A fifteen-year study in the Netherlands
on 552 Dutch men aged 50-69 found that those who drank more than
two cups of (in this case, black) tea daily were 50% less likely
to have a fatal heart attack. The same study found that those
who drank five cups of tea a day were 69% less likely to suffer
a stroke than those men who only drank half as much tea.
In a study at the University of Southern
California School of Medicine, elderly people who drank more
than two cups of tea per day and had done so for a long time
had a 63% lower risk of pancreatic cancer than people who had
drunk less than a cup per day. The Norwegian government did a
large-scale study (20,000 people) and found that the overall
death rate was lower for those who drank at least one cup of
tea per day.
Studies in both Norway and Israel have
found that tea drinkers have lower blood cholesterol. This partially
explains the reduced risk of heart disease and stroke, but it's
even better than that: studies have shown that LDL, the "bad"
cholesterol, only clogs arteries when it is damaged by oxidation.
Tea is full of phytochemicals (chemicals found in plants) which
act as powerful antioxidants. In a test-tube study of 39 food-derived
antioxidants, the phytochemicals in tea were the most
potent inhibitors of LDL oxidation. In fact, one compound in
tea was found to be 20 times stronger than the potent antioxidant
vitamin C.
One of the antioxidants in green tea is
epigallocatechin gallate (EGCG); when you brew a cup and then
let the water evaporate, half of what you have left is
EGCG. Fifty percent of the solid matter of a cup of tea is a
potent antioxidant.
We've all heard that a glass of red wine
per day is good for us, primarily because of its antioxidants,
one of the most potent being catechins. Let's compare
tea with wine: a glass of red wine contains 300 milligrams of
catechins; a cup of black tea, 210 milligrams. That's quite good;
but the winner is green tea, with a whopping 375 milligrams per
cup, and you can drive home afterwards.
A Dutch study of some 800 men found that
those who had the most flavonoids (another kind of phytochemical)
in their diet were 66% less likely to develop heart disease than
those who consumed the least. For those who got the most flavonoids,
their main source was black tea.
Research is exploding to the point where
previous studies are being re-examined. The famous "Seven
Countries Study" done in the 1960s has been re-analyzed
in light of what we now know about tea. This study achieved fame
because it was the first to show that the amount of fat in the
diet affects heart disease. Re-analyzed, it seems that a high
intake of antioxidants, mainly from tea, explains the lower incidence
of heart disease in the tea-drinking countries.
An assistant professor at the University
of Minnesota, Wei Zheng, MD, PhD, studied the tea-drinking habits
of 35,369 postmenopausal women. Over an eight-year period, the
women who drank at least two cups of tea per day had 32% fewer
cancers of the digestive tract (including colon and esophagus)
than women who only drank tea occasionally or never. They were
also 60% less at risk from cancers of the bladder and kidneys.
The women who drank at least four cups of tea had even
fewer of these cancers.
ANTIOXIDANTS AND BEYOND
The ways in which tea produces its healthy
effects go on and on. Women's livers metabolize estrogen and
then send it through the gall bladder into the bile to be eliminated.
Certain kinds of bacteria in the intestines change that estrogen
into a potent cancer-producing hormone, which is then reabsorbed
by the intestines, contributing to the development of breast
cancer. Studies show that tea stops those bacteria from changing
the estrogen into something dangerous, according to Herb Piersen,
PhD, former director of the National Cancer Institute's Designer
Foods Program.
Another way tea creates a healthy effect
is by neutralizing nitrosamines (from cured meats) and heterocyclic
amines (from cooked meats). "Drinking tea with meals in
Japan and China," says a cancer researcher at the University
of British Columbia, "is thought to be a major reason for
the low cancer rates in these countries."
Tea also helps prevent tooth decay in several
ways. It contains a solid dose of fluoride, and according to
researchers at the Tokyo Dental College, it fights the kinds
of bacteria in the mouth that cause gum disease and the eventual
loss of the teeth. It worked better, in fact, than the antibiotic
tetracycline. It also kills Streptococcus mutans, the
greatest cavity-causing bacteria in the mouth.
Substances in green tea also lower hypertension
in mice. The findings go on and on. In the test-tube, tea inhibits
the proliferation of viruses, including influenza.
There is a downside to tea: it increases
the passage of B and C vitamins and calcium through the body,
although not very much. If you take a vitamin-mineral supplement,
you're probably getting enough extra B and C vitamins to neutralize
this effect.
One of the paradoxically valuable things
about tea is that it contains caffeine. Caffeine is addicting.
Once you start drinking tea, you tend to do so regularly, and
this turns out to be a good thing. It keeps an uninterrupted
flow of antioxidants going through your cells, cleaning up the
damaging oxygen, killing dangerous bacteria, neutralizing carcinogens,
lowering your cholesterol, preventing cancer, and keeping your
veins from clogging.
Americans turned away from tea as a rebellion
against oppression. Now we're switching back. Times are changing,
and so are we — for the better, for our health. We have
a new slogan: Drink your TEA. It does a body good.
Editor's note: Iced tea works as well as
hot tea in bestowing healthy benefits, as long as it is brewed
and not instant iced tea. Iced tea is an American invention and
very rare in the rest of the world, but 80% of the tea Americans
drink is iced.
This article originally appeared in TEA a magazine
in the June/July 1997 issue.
THIS JUST IN: A new study by Purdue University researchers
discovered that tea reduces the amount of mercury from fish you
body digests. One of the dangers of eating fish is that it contains
the heavy metal, mercury. In the study, when people were given
a tea extract along with mackerel, up to 92 percent less mercury
was absorbed than those who ate fish without the tea extract.
They tried both black and green tea extracts,
which both worked well. Green tea extract worked a little better. |
