Archive for category Green tea'

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 Read more […]

Green tea: Interactions. Contraindications. Pregnancy Use. Practice Points

Adverse Reactions Due to the caffeine content of the herb, CNS stimulation and diuresis is possible when consumed in large amounts. One clinical study found an absence of any severe adverse effects when 15 green tea tablets were taken daily (2.25 g green tea extracts, 337.5 mg EGCG and 135 mg caffeine) for 6 months. Significant Interactions Controlled studies are not available for green tea, so interactions are speculative and based on evidence of pharmacological activity. Therefore, clinical significance is unknown. ANTICOAGULANTS Antagonistic interaction — a case of excessive consumption (2.25-4.5 L of green tea/day) was reported to inhibit warfarin activity and decrease the INR. Intake of large quantities of green tea should be done with caution. HYPOGLYCAEMIC AGENTS Caffeine-containing beverages can increase blood sugar levels when used in sufficient quantity (200 mg of caffeine); however, hypoglycaemic activity has been reported for green tea, which could theoretically negate this effect — the outcome of this combination is uncertain, therefore observe patient. IRON Tannins found in herbs such as Camellia sinensis can bind to iron and reduce its absorption — separate doses by at least 2 hours. Read more […]

Green tea: Uses. Dosage

Clinical Use Evidence is largely based on epidemiological studies with few clinical studies available. CANCER PREVENTION Epidemiological studies have generally shown a decreased occurrence of cancer in those individuals who drink green tea regularly, although this has not been observed in all studies. A 2003 prospective cohort study using 13-year follow-up data found increased green tea consumption was associated with an apparent delay of cancer onset and death, and all cause deaths. A phase 2 RCT evaluated the effects of green tea on oxidative DNA damage in 143 heavy smokers over 4 months and found a significant reduction in damage as evaluated from urine and plasma. A small, controlled, pilot study concluded with similar results when cells from the oral mucosa of smokers showed much less oxidative damage when compared with controls. These trials indicate that green tea may be effective in reducing cancer in smokers, but much larger trials are needed. In contrast, a 2001 prospective study in Japan found no association between green tea consumption and cancer incidence. CANCER TREATMENT Overall, the current evidence does not support the use of green tea as a cancer treatment; however, there are some exceptions, Read more […]

Green tea: Actions

Main Actions It is suspected that the polyphenol content is chiefly responsible for the chemoprotective, antiproliferative, antimicrobial and antioxidant activity of green tea. The caffeine content is predominantly responsible for central nervous system activity and an interaction between both appears necessary for increasing thermogenesis. ANTIOXIDANT Green tea has consistently demonstrated strong antioxidant activity. In a recent controlled human trial, 24 healthy women consumed 2 cups of green tea (250 mg catechins/day) for 42 days. The results showed a significant increase in plasma antioxidant status, reduced plasma peroxides and reduced LDL-cholesterol when compared with controls. Several other in vitro animal and human studies have also demonstrated that green tea inhibits lipid peroxidation and scavenges hydroxyl and superoxide radicals. ANTIBACTERIAL ACTIVITY Green tea extract has moderate and wide-spectrum inhibitory effects on the growth of many types of pathogenic bacteria, according to in vitro tests, including seven strains of Staphylococcus spp., seven strains of Streptococcus spp., one strain of Corynebacterium suis, 19 strains of Escherichia coli and 26 strains of Salmonella spp. Green tea has Read more […]

Green tea: Background

Historical Note Tea has been a popular beverage for thousands of years and was originally grown in China, dating back 5000 years, where it has been used as part of various ceremonies and to maintain alertness. Green tea and the partially fermented oolong tea have remained popular beverages in Asia since that time, whereas blacktea is the preferred beverage in many English-speaking countries. Tea was introduced to the Western culture in the 6th century by Turkish traders. Second to water, tea is now considered to be the world’s most popular beverage. Common Name Green tea Other Names Chinese tea, camellia tea, grunertea, Matsu-cha Botanical Name / Family Camellia sinensis (family Theaceae) Plant Part Used Leaf Chemical Components The composition of green tea varies according to the growing and harvesting methods, but the most abundant components are polyphenols, which are predominantly flavonoids (e.g. catechin, epicatechin, epicatechin gallate, epigallocatechin gallate, proanthocyanidins). Caffeine content in green tea varies but is estimated at about 3%, along with very small amounts of the other common methylxanthines, theobromineand theophylline. It also contains many other constituents, such as tannin, Read more […]