Green tea extract comes from the natural dried leaves of the tea plant (Camellia sinensis). Black tea is derived from oxidized green tea leaves. Both Green and Black tea have been used for thousands of years in Asia, both as a beverage and a herbal medicine.
Researchers studying green tea have found it to be an excellent source of potent, bioflavonoid-rich compound that is high in polyphenols, a special class of bioflavonoids. The most important of the polyphenols isolated from green tea are the catechins, and in particular (-)Epigallocatechin Gallate (EGCG), a strong antioxidant that is used in food production and antioxidant research.
The phenol groups in green tea polyphenols are extremely active, easily able to capture and neutralize free radicals and other pro-oxidants. Researchers have found that EGCG is over 200 times more powerful than vitamin E in neutralizing pro-oxidants and free radicals that attack lipids (oils and fats). EGCE is also 20 times more potent than vitamin E in reducing the formation of dangerous and potentially mutagenic peroxides that form in rancid fats and lard.
EGCE is also known to confer protection against respiratory and digestive infections and food poisoning, while encouraging acidophilus growth and regularizing bowel habits. In laboratory studies, 500 mg. of green tea catechins per day have been shown to significantly lower blood pressure and possess anti-mutagenic activity. Additionally, at very high levels (0.5% to 1% of daily diet) green tea catechins reduced high total- and LDL-cholesterol levels in animal studies.
Green tea blocks the attachment of bacteria to the teeth, protecting against cavities. Green tea extract is non-toxic, both in acute doses and high long-term doses. There is no potential for causing mutation or birth defects, and no adverse effect on fertility, pregnancy or nursing.