Archeological evidence suggests that tea leaves steeped in boiling water were consumed as many as 500,000 years ago. Historical evidence from China indicates that tea infusions have been used as a beverage for approximately the past 4700 years. The cultivation of tea is believed to have begun in China or India. Today, tea is the world's most popular beverage next to water. Green tea, black tea, oolong tea and white tea are all derived from the camellia sinensis plant and all have traditionally been consumed for their health benefits. The differences in the teas is in their processing. Green tea is made from unfermented leaves and is reputed to contain the highest concentration of polyphenols. In traditional Chinese and Ayurvedic medicine, green tea has been used as a stimulant, diuretic, astringent, and heart tonic.

Antioxidant properties of Green Tea

      The polyphenols in green tea are antioxidants. Antioxidants neutralize free radicals that can damage cells and induce genetic mutations. Free radicals contribute to the aging process and the development of cancer and heart disease. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (EGCG). The polyphenol that has been most researched and is believed to have the most potent health benefits is EGCG. Green tea contains roughly 30% to 40% polyphenols and black tea contains only 3% to 10% polyphenols. The average cup of green tea contains about 50 to 150 mg polyphenols.

Green Tea and Heart health

      Epidemiological studies indicate that the antioxidant properties of green tea may help prevent atherosclerosis, particularly coronary artery disease. Green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people. One epidemiological study found that men who drink green tea are more likely to have lower total cholesterol thank those who do not drink green tea. Polyphenols in green tea may block the intestinal absorption of cholesterol and promote its excretion from the body.

Green Tea and Cancer

      Epidemiological, animal and clinical studies have demonstrated anti-cancer properties for green tea. The polyphenols in green tea are believed to play an important role in the prevention of cancer. In addition to their antioxidant properties, green tea polyphenols are believed to help kill cancer cells and stop its progression.

      The types of cancers that may be favorable affected by green tea polyphenols includes bladder cancer, breast cancer, colorectal cancer, esophageal cancer, lung cancer, pancreatic cancer, prostate cancer, skin cancer, and stomach cancer. While there is evidence that green tea polyphenols may inhibit the growth of many types of cancer cells, there is enough contradictory and inconclusive results from studies to make it difficult to draw hard conclusions based on published research. Some studies show that green tea may reduce cancer rates while others suggest that it may actually increase cancer rates.

Antiviral Properties of Green Tea

      Results from several animal and human studies suggest that the polyphenols present in green tea may help treat viral hepatitis. In these studies, catechin was isolated from green tea and used in very high concentrations. It has not been proven that drinking green tea confers these same benefits to people with hepatitis.

      The catechins in green tea have also demonstrated activity against Influenza A and B viruses. EGCG was observed to have the highest antiviral activity but the other polyphenols also contributed to antiviral activity and the natural combination was more effective than any of the isolates. Recent studies done in Japan and China demonstrated that green tea catechins in general could inhibit the reverse transcriptase or polymerases of several types of viruses including HIV-1 and herpes simplex 1. Various polymeric oxidation products of polyphenols have also been found to inhibit the herpes simplex virus.

      Tea and tea extracts have also been used as a topical treatment for herpes virus outbreaks. A patent has been filed in the UK (Number 2,293,548). Joan Hibberd , a medical doctor, found that ordinary tea works better than acyclovir as a topical treatment for herpes lesions. According to Dr Hibberd, within four or five days the lesions crust over, then disappear and do not recur for at least several months after treatment.

Green Tea and Weight loss

      Green tea extract may boost metabolism and help burn fat. This effect may be attributed to the catechins in the green tea. In addition to the polyphenols, green tea also contains alkaloids including caffeine, theobromine, and theophylline. These alkaloids provide green tea's stimulant effects. Green tea has been used traditionally to control blood sugar in the body and may help regulate glucose in the body. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. Obesity is often associated with the development of diabetes.

Green Tea Fluoride and Aluminum

      Tea, including green tea, is known to contain high concentrations of fluoride and aluminum. There is evidence that in recent times the concentration of aluminum and fluoride in tea has increased as a result of exposure to increasing air and water pollution. It appears that the tea plant has a strong tendency to concentrate aluminum and fluoride. It is likely that plant concentrations of aluminum and fluoride are highly variable depending on the soil, water, cultivation practices and local pollution. This has not been adequately studied nor is it monitored.

      Fluoride in particular is a serious political issue with proponents of fluoridation claiming that fluoride is good for us and pushing for fluoridation of drinking water, table sale and dental products. The opponents content that fluoride is harmful to human health and should be restricted. The proponents have the upper hand in politics and media, but a close examination of the science validates the opponents of fluoridation.

      Fluoride is a chemical antagonist of iodine. Iodine is necessary for normal thyroid function. Much hypothyroidism is believed to be due in large part to suboptimum iodine levels. In addition, fluorosis, a disease affecting teeth and bones, especially in growing children and young adults has been epidemiologically associated with heavy tea consumption and increased consumption of caffeinated beverages which also tend to be high in fluorides.

      The element aluminum is abundant and widely distributed in nature. It is usually chemically bound in ways that make it difficult for plants to concentrate it and for the human body to absorb it. Aluminum that is absorbed into the body is believed to contribute to the development of alzheimer's disease, renal and neurological disorders. The presence of high concentrations of fluorides makes aluminum more absorbable. Studies have shown that increased aluminum absorption is associated with tea consumption.

      A more detailed and well referenced article on this topic can be found at Green Tea, Fluoride & the Thyroid

Green Tea Drug Interactions

      The U.S. Food and Drug Administration (FDA) includes tea on their list of "Generally Recognized As Safe" substances.

      Green tea does contain caffeine and people who drink excessive amounts may experience irritability, insomnia, heart palpitation, and dizziness. Caffeine overdose can cause nausea, vomiting, diarrhea, headaches, and loss of appetite.

      Some (not all) of the potential drug interactions that can occur with green tea include:

• Adenosine: The caffeine content in green tea may inhibit the hemodynamic effects of adenosine.
• Atropine: The tannin content in green tea may reduce the absorption of atropine.
• Iron supplements: The tannin content in green tea may reduce the bioavailability of iron. Green tea should be taken either 2 hours before or 4 hours following iron administration.
• Codeine: The tannin content in green tea may reduce the absorption of codeine.
• Benzodiazepines: Caffeine has been shown to reduce the sedative effects of benzodiazepines.
• Beta-blockers: Caffeine may increase blood pressure in people taking propranolol and metoprolol.
• Blood Thinning Medications: Green tea should not be taken with blood thinning medications because the herb may prevent platelets from clotting.
• Chemotherapy: Green tea may increase the effectiveness of come chemotherapy medications, specifically doxorubicin and tamoxifen. Green tea may also have an adverse effect on prostate cancer.
• Clozapine: Green tea may reduce the effectiveness of clozapine.
• Ephedrine: Green tea may increase the effects of ephedrine.
• Lithium: Green tea has been shown to reduce blood levels of lithium.
• Monoamine oxidase inhibitors: Green tea may cause a severe increase in blood pressure when taken together with MAOIs used to treat depression.
• Oral contraceptives: Oral contraceptives can prolong the amount of time caffeine stays in the body and may increase its stimulating effects.

Green Tea Summary

      Tea, including green tea, clearly has some good and bad characteristics. Most of the clinical and laboratory research has focused on the antioxidant polyphenols. This research has demonstrated numerous benefits including weight loss, heart health, anticancer effects and antiviral effects. Its negative effects are attributed to its aluminum, fluoride, caffeine and other stimulants.

      These negative effects are too well documented to be ignored. Until there is a system created to produce tea with low fluoride and aluminum content and certify its safety, consumption of tea in all forms should probably be limited. An alternative for individuals wishing to consume the beneficial polyphenols found in green tea is to use the standardized extracts that are widely available.

Where to get Green Tea Polyphenols

      For a high quality source of Green Tea Polyphenols and other Health and Life Extension Supplements:

Get Green Tea Polyphenols and other Professional Supplements from Vitamin Research Products

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