All About Green Tea And Polyphenols
-A discovery is said to be an accident meeting a prepared mind,
Albert von Szent-Gyorgyi (1893 - 1986)
Or as I like to say... When the student is ready, the teacher
shall appear! By the way, have I said how much I passionately
enjoy green tea, the personal benefits I have witnessed from
green tea and what a fantastic unearthing this 'ancient
medicine' is for modern western living?
After a good deal of research, I have found that there isn't any
other food or drink in general consumption reported to have the
innumerable health benefits that green tea possesses...none!
The Chinese have known about the medicinal benefits of green tea
since ancient times, using it to treat everything from headaches
and lethargia to depression. And did you know that green tea has
been used as a medicine in China for over 4,000 years... When
will we westerners learn?
At present, in both Asia and America, scientific research is
providing a more than solid substantiation for the health
benefits long associated with drinking green tea. For instance,
in 1994 the Journal of the National Cancer Institute published
the results of an epidemiological study demonstrating that
drinking green tea reduced the risk of esophageal cancer in
Chinese men and women by nearly sixty percent. Conversely,
University of Purdue researchers recently concluded that a
compound in green tea inhibits the growth of cancer cells. There
is also research indicating that drinking green tea lowers total
cholesterol levels, as well as improving the ratio of good (HDL)
cholesterol to bad (LDL) cholesterol.
To abridge just a few of the medical conditions in which
drinking green tea has proved to be helpful:
impaired immune system function
cardiovascular disease
cancer
rheumatoid arthritis
elevated cholesterol levels
numerous types of infections
muscle wasting diseases
Green tea's 'secret' lies in the fact it is rich in catechin
polyphenols, particularly epigallocatechin gallate (EGCG). EGCG
is a powerful anti-oxidant: besides inhibiting the growth of
cancer cells, it kills cancer cells without harming healthy
tissue. It has also been exceedingly effective in lowering LDL
cholesterol levels, and inhibiting the abnormal formation of
blood clots. The preceding takes on added importance when you
consider that thrombosis (the formation of abnormal blood clots)
is the foremost cause of heart attacks and stroke. Quite
startling, don't you think?
For The Record Books...
Correlates are being drawn between the effects of drinking green
tea and the "French Paradox." For years, researchers were
mystified by the fact that, despite consuming a diet rich in
saturated fat, the French have a lower incidence of heart
disease than Americans. The answer was found to lie in red wine,
which contains resveratrol, a polyphenol that limits the
negative effects of smoking and a fatty diet. In a 1997 study,
researchers from the University of Kansas concluded that EGCG is
twice as powerful as resveratrol, which may explain why the rate
of heart disease among Japanese men is significantly low, even
though in excess of seventy-five percent are smokers.
So why don't other Chinese teas have similar earth-shaking
health benefits? Green, oolong, and black teas all come from the
leaves of the Camellia sinensis plant. What sets green tea apart
is the way it is processed.In particular, green tea leaves are
steamed, which prevents the EGCG compound from being oxidized.
By contrast, black and oolong tea leaves are processed from
fermented leaves, which results in the EGCG being transformed
into other compounds that are not nearly as effective in
preventing and fighting various conditions and diseases.
Some Additional Benefits...
The latest evidence emerging is that green tea can even help
dieters attain success more rapidly an efficiently. In November,
1999, the American Journal of Clinical Nutrition published the
results of a study at the University of Geneva in Switzerland.
Researchers found that men who were given a combination of
caffeine and green tea extract burned more calories than those
given only caffeine or a placebo.
Incidentally, green tea can even help prevent tooth decay! Just
as its bacteria-destroying abilities can help prevent food
poisoning, it can also kill the bacterium that causes dental
plaque. Meanwhile, skin preparations containing green tea - from
deodorants to creams - are starting to appear on the market
showing positive effects.
The Potential Unsafe Effects?
As of today, the only adverse side effect reported from drinking
green tea is mild insomnia due to the fact that it contains
caffeine. On the other hand, green tea contains much less
caffeine than coffee and most soda: there are approximately
thirty to sixty mg. of caffeine in six - eight ounces of tea,
compared to over one-hundred mg. in eight ounces of coffee and
can you imagine the huge contrast in caffeine content between
green tea and these 'new' high-tech energy drinks that are
currently being consumed by the masses with such ravenous
voracity.
Green Tea Polyphenols, What Are They You Ask?
Specifically, tea polyphenols are compounds in tea leaves that
are natural plant antioxidants. Antioxidants have been proven to
prevent damage caused by free radicals to DNA and other
molecules.
How Do They Work?
Green tea polyphenols have corroborated several cancer
preventive properties. In addition to antioxidant activity,
these compounds may as previously mentioned have shown to reduce
abnormal cell growth and inflammation; help the body get rid of
cancer-causing agents; and restore communication between
different cells in the body.
On Cancer... The Facts
The relationship between green tea consumption and human cancer
has been studied in several different populations and at various
cancer sites. Some of the studies comparing green tea drinkers
to non-green tea drinkers support the claim that green
tea-drinking, in fact prevents certain types of cancer. Certain
dietary, environmental, and population differences may account
for these discrepancies. In animal studies, different tea
extracts, tea polyphenol mixtures, purified tea components, and
tea infusions as the sole drinking fluid have more consistently
been shown to prevent cancer, including cancers of the colon,
esophagus, liver, stomach, lung, breast, pancreas, and skin. The
purified component, epigallocatechin gallate (EGCG), prevented
colon cancer, but did not prevent cancer of the esophagus in
animal models. A polyphenol mixture with EGCG, called Polyphenon
E, has also shown cancer preventive properties in animals.
Animal studies were inconclusive as to whether EGCG or
Polyphenol E caused DNA mutations that might trigger cancer
growth. Both EGCG and Polyphenon E are being tested for safety
and efficacy in humans.
Slower Prostate Cancer Cell Growth Found From Consumption Of
Green And Black Tea
A study at The Experimental Biology 2004, in Washington, D.C.,
reported as part of the scientific program of the American
Society of Nutritional Sciences, anti-tumor effects of green and
black tea polyphenols in human tissue. And researchers at the
University of California at Los Angeles found and were able to
detect tea polyphenols in prostate tissue after a very limited
consumption of the tea. More notably, the scientists found that
prostate cancer cells grew more slowly when placed in a medium
containing blood serum of men who had consumed either green or
black tea for five days compared to serum collected before the
men began their tea-drinking regimen. Serum from men who drank
comparable amounts of diet or regular soda showed no such
slowing in cancer cell proliferation.
Consequently, Dr. Susanne Henning, UCLA Center for Human
Nutrition, pronounced that the UCLA research team - a
combination of nutrition scientists and urologists - focused on
the feasible outcome of tea polyphenols on factors named
polyamines and the enzymes responsible for the production of
polyamines. Elevated levels of polyamines have been connected
with malignancy in humans, including prostate cancer, and -
since polyamines are current in prostate tissue in high
concentration - are considered a logical target for
chemoprevention of prostate cancer.
Prostate cancer is one of the most widespread cancers among
males in the United States, and more than a fourth of all those
patients with prostate cancer are known to use alternative
therapies, including green tea. This study suggests that both
black and green tea are promising natural dietary supplements
useful for chemoprevention of prostate cancer, according to Dr.
Henning. She plans to investigate if this effect can be enhanced
by consuming larger amounts of tea polyphenols in the form of
green tea extract supplement capsules.
So If It's That Good, How Much Should I Drink?
Strangely enough, there are as many answers to this question as
there are researchers investigating the beneficial properties of
green tea and polyphenols. Herbs for Health magazine mentions a
Japanese report citing that men who drank ten cups of green tea
per day stayed cancer-free for three years longer than men who
drank less than three cups a day (there are approximately 240 -
320 mg of polyphenols in three cups of green tea).
Meanwhile, a study by Cleveland's Western Reserve University
concluded that drinking four or more cups of green tea per day
could help prevent rheumatoid arthritis, or reduce symptoms in
individuals already suffering from the disease. And Japanese
scientists at the Saitama Cancer Research Institute have
discovered that there were fewer recurrences of breast cancer,
and the disease spread less quickly, in women with a history of
drinking five cups or more of green tea daily.
A University of California study on the cancer-preventative
qualities of green tea concluded that you could probably attain
the desired level of polyphenols by drinking merely two cups per
day. So which is it? I personally don't buy the hype that those
that manufacture and sell green tea products are
propagating...moderation is, like with all things probably your
best bet! But given all the evidence, it is almost certainly
safe to plan on drinking four to five cups of green tea daily.
If you're a real aficionado, by all means imbibe more; but
whether or not you'll derive added health benefits remains to be
determined.
Okay, enough science... Let's all just relax and have a cup of
green tea or if you like your beverages cold like I do, a glass
of 'iced' green tea.