Green Tea (Camellia sinensis)

Medical Uses

Green tea is used as an antioxidant, for its anticancer effects, and for its effects as a sunscreen protection.

Historical Uses

Green tea was first used by Buddhists in China and India and during meditation ceremonies in Japan. Traditional Chinese medicine recommends green tea “to prolong life”).

Growth

This herb comes from a small, native Chinese evergreen tree with green pointy leaves. It is grown primarily in China, India, and Japan.

Part Used

• Fresh leaves

Green tea comes from the fresh leaf, lightly steamed to avoid oxidation of the polyphe-nol components, in contrast to black tea,which is allowed to oxidize.

Major Chemical Compounds

• Polyphenols 8 to 12 percent

Flavonoids (such as epigallo catechin gallate)

• Tannins

Quercetin

• Alkaloids (such as caffeine)

Green Tea: Clinical Uses

Green tea is used as an antioxidant, for its anticancer effects, and for its effects as a sunscreen protection.

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.

Side Effects

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.

Contraindications

• Green tea is contraindicated for infants.

Herb-Drug Interactions

Green tea should be used cautiously if the patient is taking an anticoagulant.

Pregnancy and Breast-Feeding

Pregnant women should avoid caffeine.

Pediatric Patients

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.

Katiyar et al. (1992). This study found that green tea and its compounds could prevent carcino-genesis in animal tumor bioassay systems.

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.

• Use green tea cautiously if you take a blood thinner. Green tea may increase the risk of bleeding.

• Pregnant women should avoid caffeine.