Cha Thé Tea

Thursday, December 20, 2007 Reuters

TOKYO -- Drinking green tea may reduce the risk of advanced prostate cancer, according to a study by researchers at Japan's National Cancer Center.

It said men who drank five or more cups a day might halve the risk of developing advanced prostate cancer compared with those who drank less than one cup a day.

"This does not mean that people who drink green tea are guaranteed to have reduced risk of advanced prostate cancer," said Norie Kurahashi, a scientist who took part in the study.

"We are just presenting our results. But the study does point to the hope that green tea reduces the risk of advanced prostate cancer."

Prostate cancer is much less common among Asian men than Western men, and that may be partly due to the effects of the high consumption of green tea in Asia, the study said.

But it said further studies are needed to confirm the preventive effects of green tea on prostate cancer, including well designed clinical trials.

The study, published in the American Journal of Epidemiology, compiled data from 50,000 men aged 40-69 over a period of up to 14 years from 1990.

British charity Cancer Research UK says on its Web site that a study of almost 20,000 Japanese men published in the British Journal of Cancer in 2006 found no relationship between green tea and prostate cancer.

Coffee, tea linked to lower risk of kidney cancer

Coffee and tea lovers may have a slightly reduced risk of developing kidney cancer, research hints.

Coffee and tea lovers may have a slightly reduced risk of developing kidney cancer, research hints.

The findings, based on an analysis of 13 previous studies, suggest that coffee and tea may be protective against kidney cancer, while milk, soda and juice seem to have no effect one way or the other.

Across the studies, people who drank three or more cups of coffee a day were 16 per cent less likely to develop kidney cancer than those who averaged less than a cup per day. And those who sipped just one cup of tea each day had a 15 per cent lower risk of the disease than non-drinkers.

The findings appear in the International Journal of Cancer.

While the study cannot show that coffee or tea directly lower kidney cancer risk, there are reasons why the beverages could be beneficial, according to the researchers, led by Dr Jung Eun Lee of Harvard Medical School in Boston.

For example, they explain, coffee and tea may increase the body's sensitivity to the blood-sugar-regulating hormone insulin, and researchers say that insulin levels determine whether the kidney is healthy or gets sick.

Coffee and tea also contain antioxidant compounds that may help protect cells in the kidney from cancer-promoting damage, the researchers point out.

For their study, the investigators combined the results of 13 long-term studies that included a total of 530,469 women and 244,483 men. Each study collected information on participants' diets at the outset and then followed them for seven to 20 years.

Coffee and tea consumption were linked to a lower risk of kidney cancer even when the researchers accounted for a number of factors known to affect people's risk of the disease – such as obesity, smoking and high blood pressure.

"Our results suggest that coffee and tea consumption may be associated with a modestly lower risk of (kidney) cancer, whereas intakes of milk, juice and soda were not associated with risk," Lee's team writes.(Agencies)

研究：喝茶和咖啡有助于預防腎癌

一項研究表明，愛喝咖啡和茶的人患腎癌的風險可能略低。

研究人員對此前十三項研究的結果進行了分析，分析結果表明，喝咖啡和茶能夠預防腎癌，而喝牛奶、汽水和果汁對腎臟健康則似乎沒什麼影響。

之前的研究顯示，每天喝三杯或三杯以上咖啡的人比平均每天喝咖啡不足一杯的人患腎癌的風險低16%；而且每天只喝一杯茶的人比不喝茶的人患腎癌的風險低15%。

該研究結果在《國際癌症研究期刊》上發表。

研究人員稱，盡管研究不能直接證明喝咖啡和茶能夠預防腎癌，但還是能找到一些科學依據的。該研究由波斯頓哈佛醫學院的李貞恩博士負責。

比如，咖啡和茶能夠增加人體對血糖調節激素——胰島素的敏感度。研究人員稱，胰島素水平是影響腎臟健康的主要因素。

此外，研究人員指出，咖啡和茶中含有的抗氧化物質能夠保護腎臟細胞免受傷害。

研究人員綜合分析了13項長期研究的結果，這13項研究共有530469名女性和244483名男性參加。每項研究最初都搜集了研究對象的飲食信息，然後對他們進行了為期7年至20年的跟蹤調查。

這一研究結果是在綜合考慮了可能誘發腎癌的各種因素後得出的，比如肥胖、吸煙和高血壓。研究人員在研究報告中寫道：“研究結果表明，喝茶和咖啡能略微降低患腎癌的風險，而喝牛奶、果汁和蘇打水等飲料對此則沒什麼影響。”

Sunday, December 9, 2007
By Megan Rauscher, Reuters Health

NEW YORK -- An extract of green tea wards off colorectal cancer, animal experiments show.

According to research reported at the Sixth International Conference on Frontiers in Cancer Prevention, sponsored by the American Association for Cancer Research, a standardized green tea polyphenol preparation (Polyphenon E) limits the growth of colorectal tumors in rats treated with a substance that causes the cancer.

"Our findings show that rats fed a diet containing Polyphenon E are less than half as likely to develop colon cancer," Dr. Hang Xiao, from the Ernest Mario School of Pharmacy at Rutgers University, Piscataway, New Jersey, noted in a statement.

These results are consistent with previously published results, which showed that green tea consumption was associated with lower colon cancer rates in Shanghai, China, he also noted.

In the study, Xiao and colleagues injected rats with azoxymethane, a chemical known to produce colorectal tumors that share many characteristics with colorectal cancer in humans.

Then they fed the animals a high-fat Western-style diet with or without Polyphenon E for 34 weeks. The amount of Polyphenon the animals took in was roughly equal to about four to six cups of green tea per day.

Polyphenon E decreased the total number of tumors per rat and decreased tumor size, compared with control rats that were not given Polyphenon E, Xiao told the conference.

"In the control group," he said, "67 percent of rats developed malignant tumors while in the treated group only 27 percent of rats had malignant tumors.

Most important, tea polyphenols decreased the number of malignant tumors per rat by 80 percent compared to the control group."

When the researchers analyzed blood and colon tissue samples, they found a "considerable amount of tea polyphenols in those samples in treated animals, and those levels of tea polyphenols were comparable to the human situation after ingestion of tea leaves or tea beverage," Xiao noted.

The researchers believe these findings will pave the way for clinical trials with green tea polyphenols in humans.

Print friendly - News from The China Post