This herb comes from a small, native Chinese evergreen tree with green pointy leaves. It is grown primarily in China, India, and Japan.
• Fresh leaves
Major Chemical Compounds
• Polyphenols 8 to 12 percent
• Flavonoids (such as epigallo catechin gallate)
• Alkaloids (such as caffeine)
Green Tea: Clinical Uses
Mechanism of Action
Catechins have an antioxidant role in the prevention of certain cancers. Polyphenols have antimutagenic and anticarcinogenic effects.
Green Tea: Dosage
Normal consumption in Japan is 3 cups per day with meals. Use 1 teaspoon of green tea leaves per cup of boiling water. Cool water slightly before steeping. Steep for about 3 minutes, strain, and drink. Antioxidants are released immediately in the cup. Do not reuse tea bags. Standardized green tea extract is 90 percent total polyphenols.
Green tea may elevate the international normalized ratio. It has milder caffeine side effects than black tea or coffee. Green tea made from tea bags contains about 29 to 47 mg of caffeine (1-5-minute brewing time); made from loose tea, it contains about 36 mg. Japanese green tea contains about 21 mg. Black tea made from loose tea has about 41 mg. Coffee made in a drip system has about 139 mg.
• Green tea is contraindicated for infants.
Pregnancy and Breast-Feeding
Pregnant women should avoid caffeine.
Green tea is not recommended for infants.
Summary of Studies
Imai & Nakachi (March 1995). This cross-sectional study included 1371 men over age 40. Results: Green tea acted protectively against cardiovascular disease and disorders of the liver.
Stick (1992). This in vitro study suggests that taking green tea with food exerts a protective, beneficial effect.
Mukhatar et al. (1992). Data from this study suggest that polyphenols possess antimutagenic and anticarcinogenic effects.
Wang et al. (1989). According to this study, green tea polyphenols affect carcinogen metabolism, DNA formation, and the scavenging of free radicals.
Green Tea: Warnings
• Green tea has milder caffeine side effects than black tea or coffee. Green tea made from tea bags contains about 29 to 47 mg of caffeine (1-5-minute brewing time); made from loose tea, it contains about 36 mg. Japanese green tea contains about 21 mg. Black tea made from loose tea has about 41 mg. Coffee made in a drip system has about 139 mg.
• Green tea should not be given to infants.
• Pregnant women should avoid caffeine.