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| Chinese Pu-erh tea |
Study finds tea lowers risk for all common breast cancers
The study, reported in the January edition of Cancer Epidemiology Biomarkers and Prevention, examined the association of regular tea consumption with the risk of breast cancer in a large population-based, case-controlled study completed in the U.S. Researchers examined data from 5,082 women with breast cancer between the ages of 20 and 74 years from population-based cancer registries, along with 4,501 age-matched controls. Information on usual tea consumption five years prior to the interview and other breast cancer risk factors were analyzed.
Results showed that among women less than 50 years old, those consuming three or more cups of tea per day had a 37% reduction in breast cancer risk when compared with women reporting no tea consumption. This relationship was consistent for invasive breast cancers and in situ, and for ductal and lobular breast cancers.
Whether it is Black, Green, White or Oolong, tea is the world's second most commonly consumed beverage
After water, people around the world rely on this beverage staple from ancient China. Throughout history, people have believed that tea aids the liver, destroys the typhoid germ, purifies the body, and preserves mental equilibrium. In recent times, scientists have documented that many of the health benefits of tea reported through the ages are more than folklore. Black, green, white, and oolong teas all derive their leaves from the Camellia sinensis plant. Research on tea has yielded profound results no matter which variety is used. All the teas from this magical plant provide a wealth of health benefits.
Tea provides potent flavonoids and antioxidants
Flavonoids in tea are naturally occurring compounds that have antioxidant properties. Antioxidants work to neutralize free radicals, believed to damage elements in the body over time, contribute to chronic disease, and accelerate the aging process.
Tea is a research superstar against cancer
A study from the January edition of International Journal of Cancer examined the association between endometrial cancer risk and usual consumption of black tea and coffee among 541 women with endometrial cancer and 541 women without such diagnosis at Rosewell Park Cancer Institute in New York. They found a non-significant association with endometrial cancer risk among women who reported drinking more than 2 cups of regular coffee. In women who drank more than 2 cups of tea, a significant decrease in endometrial cancer risk was shown. A significant decrease in risk was also reported for women who drank more than 4 cups of combined coffee and tea.
Tea drinking has been shown to play an important role in human cancer reduction by inhibiting uncontrolled cell growth, known as cell proliferation, and by promoting appropriate programmed cell death, known as apoptosis. A recent study found that smokers who drank four cups of decaffeinated green tea per day showed a 31 percent decrease in oxidative DNA damage in white blood cells as compared to those who drank four cups of water. Oxidative DNA damage is implicated in the promotion of many forms of cancer.
Epigallocatechin gallate (EGCG), an abundant polyphenol in green tea, may protect normal cells from carcinogens as well as eliminate cancer cells through promotion of apoptosis. In a test of EGCG with hamsters, researchers found that EGCG suppressed DNA changes and damage, and inhibited growth and multiplication of cancer cells.
Consumption of 2.5 cups or more of any tea from the Camellis sinensis plant resulted in a 60 percent drop in rectal cancer risk among Russian tea drinking women compared to those who drank less than 1.2 cups of tea per day. The women who drank between 1.2 and 2.5 cups per day had a 52 percent decrease in risk of rectal cancer.
The Iowa Women's Study, which followed post-menopausal women between the ages of 55 and 69 for eight years, found that those who drank two or more cups of tea per day had a 32 percent reduced risk of developing digestive cancers, and a whopping 60 percent decreased risk of developing urinary tract cancers.
In a large population-based control study, male participants drinking 4.5 cups of tea per day showed an 18 percent decrease in colon cancer risk, a 28 percent reduction in rectal cancer, and a 47 percent reduced risk of pancreatic cancer. Women who drank 3 cups of tea a day showed a drop in colon cancer risk of 33 percent, a decrease in rectal cancer risk of 43 percent, and a reduction of pancreatic cancer risk by 37 percent. Pancreatic cancer is an especially deadly form of cancer.
The major polyphenols of black tea and green tea have been shown to inhibit proteins which are closely associated with tumor growth and metastasis. Black tea polyphenols have also been shown to prevent oxidative DNA damage to colon mucosa.
A study at the University of Arizona found that drinking iced black tea with citrus peel provided a 42 percent reduction in risk of skin cancer, while hot black tea consumption was associated with significantly lower risk of squamous cell carcinoma.
Consumption of green or black tea decreased the number of tumors in mice following exposure to UV radiation. Topical treatment of green tea polyphenols on human skin prior to UV exposure inhibited DNA damage, thus inhibiting UV induced skin cancer. Green and black tea, or topical preparations of specific tea flavonoids, inhibited the growth of established non-malignant and malignant skin tumors in tumor-bearing mice. In addition, drinking black tea enhanced cell death in the animals.
A case-control study from China found that tea consumption decreased risk of ovarian cancer. The more tea that was consumed and the greater the frequency of consumption, the lower was the risk.
Compounds in tea work together to provide broad support for cardiovascular health
Human population studies have found that people who regularly consume three or more cups of black tea per day have a reduced risk of heart disease and stroke. Studies have shown this risk reduction may be due to improvement in cholesterol levels, blood vessel function, and reduction in oxidative damage.
Researchers are examining the mechanisms by which tea flavonoids function in maintaining cardiovascular health. Some studies suggest that several mechanisms work together to collectively improve markers. Blood vessel and endothelial function, ability of blood vessels to dilate to allow for proper blood flow, serum cholesterol levels, and LDL cholesterol are areas currently under study. All of these factors impact the risks for heart attacks, strokes, cardiovascular disease, and other cardiac events.
Tea and obesity
Preliminary research findings have suggested that drinking tea has an effect on weight, fat accumulation and insulin activity in the body. Researchers have found that:
1. Green tea extract significantly increased 24 hour energy expenditure and fat oxidation in healthy men.
2. The weight of modestly obese patients decreased by 4.6 percent, and waist circumference decreased by 4.48 percent after three months of consumption of green tea extract.
3. Mice fed tea catechins for 11 months showed a significant reduction of high-fat, diet-induced body weight gain and visceral and liver fat accumulation.
4. Fat cell assay testing found that tea, as normally consumed, increased insulin activity more than 15 fold. Green, black and oolong tea all yielded insulin increasing results. Several known compounds found in tea were shown to enhance insulin and help cells recognize and respond to insulin.
Tea and osteoporosis
Although it has been suggested that caffeine intake is a risk factor for reduced bone mineral density (BMD), research shows that tea drinking does not negatively impact BMD, and preliminary research suggests that tea may even be protective of bone health. A study published in the April, 2000 American Journal of Clinical Nutrition found that older women who drank tea had higher BMD measurements than those who did not drink tea. The researchers suggested that flavonoids in tea might influence bone mass.
Green and white teas are the least processed
Although black, green, white and oolong teas all come from the same plant, each is processed differently. The more processing tea leaves undergo, the darker they will turn, indicating black tea to be the most processed variety. White tea is derived from young silvery leaves in early spring. It contains no chlorophyll. Black and oolong teas are partially dried, crushed and fermented, while green and white teas are simply steamed. Regardless of the processing method, each of these teas contains polyphenols. In fact, tea ranks as high as or higher than many fruits and vegetables in ORAC score, a measure of free radical scavenging ability.
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