Monday, May 25, 2009

Green Tea

Go to Health – Green Tea

Archeological evidence suggests that people consumed tea leaves steeped in hot water as many as 500,000 years ago! Green tea tastes good, and is both energizing (caffeine) and calming (theanine). Recently scientists have been investigating the potential cancer preventive and therapeutic effects of green tea. The polyphenols in green tea, known as catechins, are considered to be the beneficial molecules The most active of these is known as EGCG (epigallocatechin gallate). Researchers at the Medical Sciences Center, University of Wisconsin-Madison have found that EGCG has several ways in which it may be active against cancer - altering the expression of genes involved in cell growth and division, growth of new blood vessels in the cancer (angiogenesis), cancer cell death (apoptosis) and metastasis. These laboratory studies have been augmented by population-based studies in groups of people who drink a lot of green tea – mostly in China and Japan. Such studies are suggestive, but not definitive.

*Bladder Cancer – women who drank black tea and powdered green tea were less likely to get bladder cancer, and men with bladder cancer who drank green tea had a better survival rate.

*Breast Cancer - In one study of 472 women with various stages of breast cancer, researchers found that women who consumed the most green tea experienced the least spread of cancer. Women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to suffer recurrences of the disease after completion of treatment. However, women with late stages of breast cancer experienced little or no improvement from drinking green tea. . In one very large clinical study from Japan, researchers found that drinking green tea was not associated with a reduced risk of breast cancer.
*Ovarian Cancer - In a clinical study conducted on ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day survived longer with the disease than those who didn’t drink green tea. In fact, those who drank the most tea lived the longest.

*Prostate Cancer - Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study conducted in Southeast China researchers found that the risk of prostate cancer declined with increasing frequency, duration and quantity of green tea consumption. However, both green and black tea extracts also stimulated genes that cause cells to be less sensitive to chemotherapy drugs. Given this potential interaction, people should not drink black and green tea (as well as extracts of these teas) while receiving chemotherapy.

Pancreatic Cancer - In one large-scale clinical study researchers compared green tea drinkers with non-drinkers and found that those who drank the most tea were significantly less likely to develop pancreatic cancer.. However, it is not clear from this population-based study whether green tea is solely responsible for reducing pancreatic cancer risk.

*Colorectal, Esophageal, Lung, Stomach Cancer -– conflicting results, including possible increased risk. Extremely hot drinks are can damage the esophagus.

Green tea extracts are also being studied for possible help with inflammatory bowel disease, diabetes, alcoholic liver disease, arthritis, weight loss, dental caries, genital warts, and even prevention of cold and flu symptoms. Stay tuned for more studies.

Green tea contains 20-30 mg of caffeine per cup, compared to 100 mg in a cup of coffee; you can also make decaf green tea.. Pills containing green tea extracts are available, some without caffeine.
Sadja Greenwood, MD - back issues on my blog –

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