GREEN TEA
SCIENTIFIC NAME: Camellia sinensis L. Kuntze. Family: Theaceae
COMMON NAMES: Tea, Green tea, AR25®, Camellia, Camellia assamica, Camellia sinensis, Camellia sinensis (L.) Kuntze, Camellia tea, Catechins, Chinese Tea, EGCG, Epigallocatechin-3-gallate, Exolise®, GTE, Green Tea Extract, Matsu-cha Tea, Thea sinensis, Thea bohea, Thea viridis, Theanine, Theifers.
HISTORY
The dried, cured leaves of C. sinensishave been used to prepare beverages for more than 4000 years.3 The method of curing determines the nature of the tea to be used for infusion, and green tea is type of cured tea. Green tea is prepared from the steamed and dried leaves; by comparison, black tea leaves are withered, rolled, fermented, and then dried. Oolong tea is semifermented and considered to be intermediate in composition between green and black teas. Green tea is less popular in America and Europe than the black tea varieties. Tea has been used medicinally for centuries, and the Chinese regarded the drink as a cure for cancer, although the tannin component is believed to be carcinogenic. Tea has been known to act as a diuretic and has been used to relieve headaches.
USES
Uses based on scientific evidence
Cancer prevention
Heart attack prevention
High cholesterol
Mental performance/alertness
Memory enhancement
Dental cavity prevention
Sun protection
Asthma
Weight loss
Arthritis
Menopausal Symptoms
Uses based on tradition, theory or limited scientific evidence
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Alcohol intoxication, antioxidant, astringent, bone density improvement, cataracts, cognitive performance enhancement, Crohn's disease, detoxification from alcohol or toxins, diabetes, diarrhea, diuretic (increasing urine), fibrosarcoma, flatulence, fungal infections, gastritis, gum swelling, headache, heart disease, Helicobacter pylori infection, HIV/AIDS, improving blood flow, improving urine flow, improving resistance to disease, inhibition of platelet aggregation, ischemia-reperfusion injury protection, joint pain, kidney stone prevention, liver cancer, longevity, lung cancer, neuroprotection, oral leukoplakia, ovarian cancer, Parkinson's disease prevention, promotion of digestion, protection against asbestos lung injury, regulation of body temperature, stimulant, stomach disorders, bleeding of gums or tooth sockets, stroke prevention, sunburn, tired eyes, vomiting.
TOXICOLOGY
There is evidence that in animals caffeine can be teratogenic, and the FDA has advised that women who are or may become pregnant should avoid caffeine-containing products. Caffeine-containing beverages may also alter female hormone levels, including estradiol.
There is evidence that condensed catechin tannin of tea is linked to a high rate of esophageal cancer in regions of heavy tea consumption. This effect may be overcome by adding milk, which binds the tannin, possibly preventing its detrimental effects.
SUMMARY
Green tea is a widely popular beverage, particularly in Asia. Because of its unique preparation process, green tea retains many of the chemical characteristics of the fresh leaf. Pharmacologically, a wealth of information is available concerning green tea's effects on lipid levels, dental caries prevention, antimicrobial, antimutagenic, and antioxidative actions. It appears that green tea components may exert a chemoprotective effect that may contribute to a reduced incidence of cancers and other life-threatening diseases. Because of the caffeine present in the tea, it should be avoided by pregnant women. The tea may be an asthma-inducing agent.
PATIENT INFORMATION — Green Tea
Uses: Traditionally consumed as a beverage, green tea retains many chemicals of the fresh leaf. It is thought to reduce cancer and other fatal diseases, lower lipid levels, help prevent dental caries, and possess antimicrobial, antimutagenic, antioxidative, and other effects.
Side Effects: The FDA advises those who are or may become pregnant to avoid caffeine. Heavy consumption may be associated with esophageal cancer. Tea may impair iron metabolism.
Dosing: Green tea has been studied as a component of diet for its cancer preventative and caries preventative properties. A typical tea bag contains 2 g of leaf. Doses of 4 to 5 cups/day (corresponding to ca. 300 mg caffeine) are considered high, depending on the patient's caffeine tolerance. The content of polyphenols increases with extended brewing time. Green tea extracts are available standardized to 25%, 60%, and 80% total polyphenols, compared with a content of 8% to 12% in the leaf. Use of this extract can avoid the inconvenience of drinking large volumes of liquids.
