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``Based
on epidemiological and mouse models, we can say drinking
four or five cups a day may be very helpful for protection,''
the report's author, Santosh Katiyar of Case Western Reserve
University, said in a phone interview.
But
he cautioned that green tea was a preventive step, not
a cure, for skin cancer.
``It
is a prevention. ... As long as I take it, I am protected,''
said Katiyar, who drinks two cups of green team a day.
The
report appeared in the Archives of Dermatology, a journal
published by the American Medical Association.
The
leaf and bud of the camellia plant are the basis of both
green and black tea. But unlike black tea, which is fermented,
green tea is steamed dry immediately after harvesting,
which leaves it with larger amounts of polyphenols.
Its
most effective polyphenol is epigallocatechin gallate
(EGCG), the report said.
Past
studies of mice exposed to ultraviolet light have shown
that feeding them green tea or applying EGCG to their
skin protected them from the reddening, blistering and
cell division associated with the early stages of skin
cancer.
Recent
experiments have shown that when applied to human skin
that has been exposed to the sun, EGCG prevented both
inflammation and the development of leukocytes, white
blood cells that can be a marker for cancer, Katiyar said.
Many
skin care manufacturers have used the mouse research to
justify including green tea extracts in their skin care
products, he said. But he challenged the effectiveness
of skin care products incorporating green tea.
``It
is unlikely that these skin care products have been tested
in controlled clinical trials, and the concentration of
(polyphenolic compounds) in these preparations is not
uniform,'' he said. He urged further clinical testing
and trials.
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