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Epigallocatechin gallate (EGCG) is one of four major catechins in
green tea.
Catechins belong to the flavan-3-ol class of flavonoids. Green tea
catechins are the flavan-3-ols found in green tea leaves. All
catechins including EGCG are polyphenolic substances. Black tea
leaves have a much lower content of these catechins. That's because
black tea leaves undergo extensive fermentation, during which the
majority of the catechins are enzymatically oxidized to the major
pigments of black tea leaves, theaflavin and
thearubigen.
Green tea catechins, especially EGCG, make up
approximately thirty percent of the dry weight of green tea leaves.
Of the catechins, EGCG is the most abundant one in green tea leaves.
Green tea has and continues to be a popular beverage in the Orient
(especially in China and Japan). In this region, it is thought to
have a number of health-promoting benefits, and it is used in the
management of various disorders. Clinical studies suggest that green
tea may have cancer chemo preventive, as well as anti-atherogenic
properties.
The catechins in green tea are responsible for
the possible health benefits of the plant. These catechins are
antioxidants with EGCG appearing to be the most power antioxidant of
all the green tea catechins.
Dosage and
Administration
A large number of green tea extract
formulas containing EGCG are used today. EGCG is the principal
catechin in these supplements. An average dose of green tea is 125
mg to 250 mg daily. However, other research suggests as much as 10
cups (2,500 ml) per day is necessary to obtain observable benefits
from green tea ingestion.
To brew green tea, 1 teaspoon (5
grams) of green tea leaves are combined with 1 cup (250 ml) of
boiling water and steeped for three minutes. Other forms of green
tea supplementation are available in the form of ingestible tablets
and capsules containing standardized extracts of
EGCG.
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