About Green Tea EGCG

What is 10EGCG® green tea?

It is a tea beverage that contains at least 710 mcg/ml (-)epigallocatechin gallate (EGCG). This represents the chemical antioxidant level that the National Cancer Institute (NCI) defines as “typical” green tea used in cancer research and in potential cancer controls. Based on laboratory studies and human data observed in traditional green tea-drinking populations, the NCI calculated the lowest effective anticancer dose in an average adult to be an equivalent of 800 ml per day of this "typical" green tea. Many cancer experts recommend daily consumption of 1.5 times this dose for chemoprevention. Since 1% of dry tea leaves in hot water is customarily used to brew green tea, the typical dry green tea leaves must contain at least 7.1% extractable EGCG in dry weight to meet this NCI standard.

[Reference: NCI, DCPC, Chemoprevention Branch and Agent Development Committee, Clinical development plan: tea extracts green tea polyphenols epigallocatechin gallate. J Cell Biochemistry 1996;26S:236-257.]

What is the relationship between EGCG and other chemical names, such as polyphenols, flavonoids (flavanoids), catechins, and antioxidants?

EGCG is a specific chemical and can be defined and measured in weight. It is one of the four catechins in green tea, being the most abundant and most active antioxidant of the four. Therefore, it is chosen as the surrogate yardstick to measure the antioxidant level in tea drinks and in tea leaves. EGCG is the most active antioxidant of the tea catechins, which are chemically members of the flavonoid category, which are in turn polyphenols. Not all flavonoids and not all polyphenols have antioxidant properties. After the tea catechins have lost their antioxidant activities, they can still be referred to as flavonoids or polyphenols. Unlike EGCG, the amount of flavonoids or polyphenols in a tea beverage does not reflect its antioxidant strength.

How are green tea leaves graded?

Traditionally, green teas are graded by aroma, taste and appearance of the tea leaves. In general, the tips or the young leaves of plants harvested in early spring are the highest grades and have been valued at about two ounces of pure gold per pound for the past 1,000 years in China and Japan. These expensive green teas usually meet the 710EGCG® standard. However, there is no absolute correlation between price and the EGCG level in green teas.