catechin
May Help Prevent
Alzheimer's
disease
The compounds
principally responsible for this
cornucopia of health benefits belong
to a class of strongly antioxidative
polyphenols called catechins.
One catechin stands out from the
rest as a kind of biochemical
superstar: epigallocatechin
gallate (EGCG), which has been
described as possibly the most
potent natural anticancer agent yet
discovered. Fortunately, it turns
out that EGCG is the most prevalent
of the catechins in green tea.
The catechin content of black tea is
much lower than that of green tea,
owing to the oxidative fermentation
process by which tea leaves are
converted from green to black
(sometimes the fermentation is
carried out only partially, the
result being oolong tea). The
fermentation destroys most of the
catechins (mainly by causing their
polymerization) and, therefore, most
of their biological activity. But in
another stroke of good fortune, it
turns out that the polymeric
compounds to which some of the
catechins are converted—called
theaflavins and thearubigins—have
significant health virtues of their
own. Thus black tea, although it has
only about one-sixth the antioxidant
power of green tea, is still a
potent beverage in its own right.
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