A green tea extract may pack
a stronger antioxidant punch than the beverage itself
does, new research suggests.
The findings, say the
study authors, indicate that a capsule can retain the
benefits of tea, without the caffeine.
Green tea extract could
therefore be used in clinical trials looking at whether
large doses of tea antioxidants can lower the risk of
certain cancers, the researchers report in the American
Journal of Clinical Nutrition.
A number of studies have
suggested that green tea may have health benefits that
include a lower risk of heart disease and certain cancers.
Researchers suspect the explanation may lie in plant
compounds called flavonoids, which are found in tea,
wine, and a variety of fruits and vegetables. Flavonoids
act as antioxidants, which means they help counter the
potentially cell-damaging effects of substances found
in the body called oxygen free radicals.
For the new study, Dr.
Susanne M. Henning and her colleagues at the University
of California, Los Angeles, tested 30 volunteers' absorption
of antioxidants from a single, large dose of green tea,
black tea or green tea extract in the form of a capsule.
Every participant was
given each of the teas and the extract, on three separate
occasions. After drinking the tea or taking the capsule,
the men and women gave several blood samples over the
following 8 hours.
Henning and her colleagues
found that while volunteers consumed equal antioxidant
doses from the teas and the extract, the latter got
more of the antioxidants into their blood.
The findings, according
to the researchers, suggest that antioxidants from green
tea extract are more easily absorbed, and lead to a
"small but significant increase" in antioxidant activity
in the blood.
"Our findings," Henning's
team concludes, "suggest that green tea extract supplements
retain the beneficial effects of green and black tea."
These extracts, they
add, could be used in future cancer-prevention research
to provide large antioxidant doses without the side
effects of caffeine.
SOURCE: American Journal
of Clinical Nutrition, December 2005.
