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Tea was discovered in China more than 4,000 years ago and
today is one of the world's most popular drinks. All teas
are made from the leaf of the Camellia sinensis plant and
there are only three types of tea--green, oolong, and black.
They differ only in the duration of fermentation. Black tea
is fully fermented, oolong is partially fermented, and green
is not fermented at all, only steamed. Types of tea, like
Ceylon and Darjeeling, refer to the region where the tea is
grown. Herbal and flavored teas are an infusion of
ingredients other than or in combination with Camellia
sinesis.
But tea is more than a steamy, comforting brew. Evidence
of green tea's health-promoting properties is becoming more
widespread, says Nicole Nisly, M.D., UI Health Care
physician specializing in alternative medicines at the UI
Family Care Center. The Chinese have known about the
medicinal benefits of green tea since ancient times, using
it to treat everything from headaches to depression.
Western research is providing evidence supporting the
health benefits of drinking tea, especially green tea. "I
recommend green tea regularly to my patients with cancer,"
says Nisly. The Journal of the National Cancer
Institute has published several articles about green
tea, including the results of an epidemiological study
indicating that drinking green tea reduced the risk of
esophageal cancer in Chinese men and women by nearly 60
percent.
There is also research indicating that the antioxidants
in green tea lower total cholesterol levels, as well as
improve the ratio of good (HDL) cholesterol to bad (LDL)
cholesterol. Green tea is loaded with catechin polyphenols,
a type of photochemical with 100 times the antioxidant kick
of vitamin C.
But beware, you'll have to swallow a lot of green tea to
gain some of the health-promoting benefits. While there are
no scientific standards set for how much green tea can be
beneficial, studies touting the success of green tea report
that subjects drank between three and six cups of tea daily.
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A good cup of tea
While a good cup of tea is as distinctive as the person
drinking it, here are a few tips on how to brew a cuppa to
get the most health benefits from green tea:
Size of tea leaves--small loose leaf green tea is
the best choice because it infuses quickly.
Loose leaf or teabag--loose leaf is best. If you
use a teabag, continually dunk the teabag in the water to
increase extraction of the catechin polyphenols.
Water temperature--boiling water promotes the
extraction of catechin polyphenols.
Steeping time--for two to five minutes. Catechin
polyphenols content increases with steeping time.
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For more information:
Listed above are several Web sites that offer additional
information on this topic. University of Iowa Health Care
does not sponsor or endorse these sites, or guarantee the
accuracy of the information contained on these sites. These
links are here for general information only, and should not
be used for personal diagnosis or treatment. If you have any
questions, please contact UI
Health Access.
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