walnut

A diet with whole walnuts was fed to mice that had been genetically programmed to get prostate cancer. After 18 weeks, researchers 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. (Courtesy: iStockphoto)

UC DAVIS (US)—Walnut consumption slows the growth of prostate cancer in mice and has beneficial effects on multiple genes related to the control of tumor growth and metabolism.

“This study shows that when mice with prostate tumors consume an amount of walnuts that could easily be eaten by a man, tumor growth is controlled,” says Paul Davis, a nutritionist at University of California, Davis. “This leaves me very hopeful that it could be beneficial in patients.”

Davis announced the findings March 22 at the annual national meeting of the American Chemical Society in San Francisco.

Numerous clinical studies have previously demonstrated that eating walnuts—rich in omega-3 polyunsaturated fats, antioxidants, and other plant chemicals—decreases the risk of cardiovascular disease. These findings prompted the U.S. Food and Drug Administration in 2004 to approve, for the first time, a qualified health claim for reducing heart disease risk for a whole food.

A diet with whole walnuts was fed to mice that had been genetically programmed to get prostate cancer. After 18 weeks, researchers 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.

The researchers 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.

Davis and his 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 where truly promising results that have a molecular footprint are having beneficial effects against cancer,” says Ralph deVere White, director of the UC Davis Cancer Center and a prostate cancer researcher.

Davis says 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.”

The research was funded by a grant from the California Walnut Board.

UC Davis health news: www.ucdmc.ucdavis.edu/newsroom/releases/