Two foods commonly eaten as part of the traditional Chinese diet can reduce a woman's risk of breast cancer by as much as 90 percent, according to a study conducted by researchers from the University of Western Australia in Perth, and published in the International Journal of Cancer.

Researchers compared consumption of mushrooms and green tea between two groups of Chinese women, one with breast cancer and one without. They found that women who ate at least 10 grams (0.35 ounces) of fresh mushrooms per day had a 64 percent lower risk of developing breast cancer than those who did not eat as much. Those who also regularly drank green tea reduced their risk by a total of 90 percent. Dried mushrooms also reduced breast cancer risk, although they were not as effective as fresh ones.

The protective benefit of mushrooms and green tea remained significant even after researchers adjusted for other breast cancer risk factors, including weight, exercise, smoking and education level.

Breast cancer rates are four to five times lower in China than in most Western countries, a fact widely attributed to a different lifestyle.

"Breast cancer incidence rates do vary in different countries, and China has lower rates than the United Kingdom," said Sarah Cant of Breakthrough Breast Cancer. "This is likely to be due to cultural and lifestyle differences such as having children earlier or exercising more [as well as diet]."

Previous research has supported the cancer-fighting properties of both mushrooms and green tea. Mushrooms are believed to suppress tumor growth and boost the immune system, and may also block production of the hormone estrogen. Green tea contains polyphenols, which have been shown to remove free radicals from the blood and hamper breast tumor development.

Julie Sharp of Cancer Research UK noted that mushrooms and green tea alone cannot make up for an otherwise unhealthy lifestyle.

"It is important to remember there is no one particular 'super' food that will protect you from cancer," she said. "Large scientific studies have proven that the best way to reduce your risk of many cancers is to eat a healthy balanced diet."