``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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