Davis fed a diet with whole walnuts to mice that had been genetically programmed to get prostate cancer. After 18 weeks, they found that consuming the human equivalent of 2.4 ounces of walnuts per day resulted in significantly smaller, slower-growing prostate tumors compared to mice consuming the same diet with an equal amount of fat, but not from walnuts. They also found that not only was prostate cancer growth reduced by 30 to 40 percent, but that the mice had lower blood levels of a particular protein, insulin-like growth factor (IGF-1), which has been strongly associated with prostate cancer. Additionally, Davis and his research colleagues looked at the effect of walnuts on gene activity in the prostate tumors using whole mouse gene chip technology, and found beneficial effects on multiple genes related to controlling tumor growth and metabolism.

"This is another exciting study from UC Davis nutrition researchers, where truly promising results that have a molecular footprint are having beneficial effects against cancer," said Ralph deVere White, UC Davis Cancer Center director and a prostate cancer researcher. "We have to find a way to get these kinds of studies on nutritional products funded so that we can truly evaluate their effects on cancer patients."

Davis, whose research was funded by a grant to UC Davis from the California Walnut Board, said additional research is needed to further explore how walnuts reduce tumor cell growth.

"The bottom line is that what is good for the heart -- walnuts -- may be good for the prostate as well," he said.

Source: University of California - Davis - Health System