Mushrooms, green tea may lower breast cancer risk

NEW YORK Fri Mar 13, 2009 3:27pm EDT

NEW YORK (Reuters Health) - Women who get plenty of mushrooms and green tea in their diets may have a lower risk of developing breast cancer, new study findings suggest.

The study, of more than 2,000 Chinese women, found that the more fresh and dried mushrooms the women ate, the lower was their breast cancer risk.

The risk was lower still among those who also drank green tea everyday.

It's known that the rate of breast cancer in China is four- to five- times lower than rates typically seen in developed countries -- though the rate has been climbing over the past few decades in the most affluent parts of China.

The current findings suggest that traditional diets -- and specifically, large quantities of mushrooms and green tea -- may help explain China's lower breast cancer incidence, according to lead researcher Dr. Min Zhang, of the University of Western Australia in Perth.

She and her colleagues report the findings in the International Journal of Cancer.

The study was conducted in southeast China and involved 1,009 breast cancer patients between the ages of 20 and 87, and an equal number of healthy women the same age. All completed a detailed dietary questionnaire that asked them how often they ate specific foods.

Overall, Zhang's team found, women who ate the most fresh mushrooms -- 10 grams or more per day -- were about two thirds less likely to develop breast cancer than non-consumers of mushrooms. Meanwhile, women who ate 4 grams or more of dried mushrooms per day had half the cancer risk of non-consumers.

Finally, mushroom eaters who also drank green tea everyday had only 11 to 18 percent of the breast cancer risk of women who consumed neither.

The study does not prove cause-and-effect, the researchers point out.

They did account for several kinds of risk factors for breast cancer - such as the women's weight, education level, and exercise frequency and smoking habits -- but there could be other factors that explain the findings.

This is also the first study linking high dietary amounts of mushrooms and green tea to lower breast cancer risk, Zhang told Reuters Health.

Therefore, she said, it's too early for women to assume that the foods will help them avoid the cancer.

Still, it is biologically plausible, the researchers point out.

Lab research has shown that mushroom extracts have anti-tumor properties and, in animals, can stimulate the immune system's cancer defenses. For its part, green tea contains antioxidant compounds called polyphenols that have been shown to fight breast tumors in animals.

SOURCE: International Journal of Cancer, March 15, 2009.

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