History Green tea is made from the dried leaves of Camellia sinensis, a perennial evergreen shrub. Green tea has a long history of use, dating back to China approximately 5,000 years ago. Green tea has been used as traditional medicine in areas such as India, China, Japan and Thailand to help everything from controlling bleeding and helping heal wounds to regulating body temperature, blood sugar and promoting digestion.
Green or Black? Green tea and black tea are derived from the same leaf. The difference lies in how they are processed. When making green tea the leaves are plucked processed immediately to prevent them from fermenting. Unfermented leaves contain large amounts of catechins, which are powerful disease fighters and potent antioxidants. When making black tea, the leaves are picked and are left to ferment. This changes the chemical structure of the catechins into substances called thearubigens and theaflavins, which have some health benefits but not nearly as many as the catechins.
Brewing and Dosage Generally, 2.25 grams of tea per 6 ounces of water, or about one teaspoon of green tea per cup, should be used. The average 6-ounce cup of green tea contains between 50 and 100 mg catechins. Most studies have concluded that you need 3-10 cups of green tea per day, or up to 1,000 mg. of catechins in order to get the healthy benefits of green tea
What Can Green Tea Prevent? Alzheimer’s disease Parkinson’s disease Cancer HIV multiple sclerosis LDL cholesterol Cardiovascular disease Raise metabolism insulin sensitivity hypertension tooth decay cholera And anything else you can think of….
Catechins  family of flavan-3-ols – Sub group of flavanoids –technically not a flavanoid due to lack of carbonyl group Are polyphenyl groups which have been shown to have anti-oxidant and anti-carcinogenic properties Catechins make up slightly less than 30% of dry weight
Catechins Epicatechin and epogallocatechin most commonly found in nature Epigallocatechin gallate most frequent catechin found in Green Tea – Thought to hold most antioxidant activity – Gallic acid attached to catechin Gallic acid found freely and within tannins in many other plants
Other Active Components Vitamin C – antioxidant B Vitamins – Metabolize carbohydrates – Manufacture fatty acids and amino acids Vitamin E – Antioxidant Fluoride – Protection of tooth decay and gum disease – Caffeine (3-4%) – About a quarter of that of coffee
The Asian Paradox  Next to Green Tea, cigarettes are mostly widely consumed product in Asia Asians have some of the lowest cardio-related death rates in the world Clinical studies have been performed to view different aspects and health benefits of green tea that lead to this paradox
Pharmacokinetics  Changes in blood count and blood chemistry profiles not significant in individuals given EGCG dosages Non-significant difference in amount of tea catechins found after initial dosage and 4 weeks later after daily regimen of EGCG at 800 mg/day and 400 mg/ day >60% increase in the systemic availability of free EGCG after chronic green tea polyphenol administration at 800 mg/day
Pharmacokinetics  Side Effects found in this study: – Excess gas – Upset stomach – Heartburn – Abdominal pain – Dizziness – Headache – Muscle pain All reported as mild events
Pharmacokinetics  Found that EGCG levels rose significantly at about 3 hours and peaked between 8-15 hours after a single dosage 90% of EGC and EC excreted in urine between 0-8 hours Supports other study with similar results
Clinical Trials; Heart Disease In a double-blinded, randomized, placebo-controlled trial,240 adults were given either theaflavin-enriched green tea extract in form of 375mg capsule daily or a placebo. After 12 weeks, patients in the tea extract group had significantly LDL cholesterol and total cholesterol (16.4% and 11.3% lower than baseline, p<0.01) than the placebo group  A meta-analysis examining the effect of green tea on cardiovascular heart health found a decrease in the rate of heart disease outcomes with increasing tea consumption.  However, two studies from the United Kingdom  and two studies from the United States  indicated an increased risk with increasing tea consumption, whereas the other studies indicated a decrease in risk.
Clinical Trials; Cancer EGCG and other tea polyphenols inhibited growth of human lung cancer cell line, PC-9 cells with G 2 /M arrest.  Many studies have studied the inhibitory effects of EGCG and green tea extract on carcinogenesis in various organs of rodents 
Skin Cancer  2 groups of lab mice (30 each) subjected to equal amounts of UVB radiation One group treated with 1.25% green tea drinking water and other with 2.5% green tea drinking water, control with distilled water Decreased number of skin tumors and substantially reduced size of tumors
Breast Cancer  In vitro – green tea catechins inhibits proliferation of ER-positive MCF-7 breast cancer cells In vivo – Mice studied had increased levels of catechins in mammary fat pads and levels were relative to how much tea was administered to each group In both aspects of the study catechins used with tamoxifen, a orally active selective estrogen receptor modulator, showed the best results in comparison to catechins or tamoxifen alone
Clinical Trials; Obesity Mice that were fed high fat diets supplemented with tea catechins for 11 months resulted in a significant reduction of diet-induced weight gain  Ingestion of tea catechins stimulated O 2 consumption and energy expenditure and decreased the respiratory quotient in humans.  Injection of EGCG modulates appetite and reduces food intake through the leptin receptor-independent pathway in rats.
Clinical Trials; Diabetes Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat models of diabetes  Some studies have shown that plasma glucose levels in diabetic rats are lowered when the rats are given (-) epicatechin  
Gastrointestinal  Test of each catechin found in green tea to find which best treats GI infection by Helicobacter pylori – chronic gastritis, peptic ulceration, and gastric cancer In vivo study – Mongolian gerbils inoculated with equal levels of H. pylori – fed different diet containing (0,.5, 1, or 2%) catechins for 2 weeks – H. pylori was eradicated in about 10% of the gerbils – In ones not eradicated, 10-36% decrease of H. pylori – Similar to success rate in human cell in vitro studies with antibiotics – More studies need on impacts of catechins on H. pylori other than eradication
Epidemiological Studies  Few have been done and ones completed take place in Asia So many variables to account for, e.g. smoking, alcohol consumption, diet, exercise it is hard to derive results One study looked at over 18000 men from Shanghai and said there was a slight decrease in cancer rates, but results seem to be unverifiable due to high variability of subjects
Contraindications  Caffeine only substance that has potential to do harm – Pregnant/nursing women should limit caffeine intake Should not be taken if used with Warfarin – Vitamin K interacts with anticoagulation
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