Green Tea May Fight Cancer
A new Japanese study has found that drinking 5 or more cups of green tea per day may significantly reduce the risk of blood and lymph based cancers, such as leukemia, lymphoma and myeloma.
The study, led by Toru Naganuma from Tohoku University School of Medicine in Japan, was published online in the July 2009 issue of the American Journal of Epidemiology.
The study included 41,761 Japanese adults aged 40-79 years with no history of cancer at the beginning of the study.
Researchers determined green tea consumption using food frequency questionnaires which the participants completed in 1994.
During nine years of follow-up, 157 cancers of the blood were documented, including 119 cases of lymphoid tumors and 36 cases of bone marrow tumors.
When the researchers compared the participants who drank 5 or more cups of green tea daily to those who drank 1 or less they found a 42% reduction in incidences of blood and lymph based cancers.
While this study does not prove that the lower cancer rates are due to green tea consumption, these results do support a large number of previous studies which have linked tea consumption with a number of health benefits.
These various health properties, which range from heart health to digestion to protection from osteoporosis, are often attributed to naturally occurring antioxidants in tea leaves called polyphenols.
There are several types of tea, the most popular being green, black and more recently, white. All are from the same plant (Camellia sinensis) and vary only in the amount of oxidation they are exposed to during fermentation, which directly effects polyphenol levels.
White tea is purported to contain the greatest percentage of polyphenols because it is not fermented or oxidized. Green tea is slightly oxidized and contains the second highest level of polyphenols. Black tea, which is green tea that has been oxidized by fermentation, contains the least amount of polyphenols of the three.