Men's health

Walnuts may help prevent prostate cancer

Slows tumour growth, says new study

Eating walnuts may help prevent prostate cancer, new research suggests.

Each year around 35,000 men are diagnosed with prostate cancer in the UK, and 10,000 die from it.

But experiments carried out on mice have shown that eating walnuts on a daily basis can reduce both the size and growth of prostate cancer.

Walnuts are a rich source of healthy nutrients including omega-3 fatty acids, gamma tocopherol (a form of vitamin E), antioxidants and polyphenols.

Past research by scientists from the University of California at Davis found that walnuts can help fight heart disease by lowering the level of endothelin in the blood, a compound linked to the inflammation of blood vessels.

As men with prostate cancer have higher levels of endothelin, the scientists wanted to know whether eating walnuts could benefit people with the disease.

Using mice which had been genetically altered to develop prostate cancer, the scientists found that mice which had been fed walnuts as part of their diet developed significantly smaller prostate tumours. Tumour growth was also slowed by 30% to 40% compared to mice fed an ordinary diet.

The mice were fed with the equivalent of approximately a handful of complete walnuts a day, rather than a supplement.

"We decided to use whole walnuts in the diet because when a single component of a food linked to cancer prevention has been tested as a supplement, that food's cancer-preventitive effects disappear in most cases," said Dr Paul Davis, who led the study.

They also found that the mice who were fed walnuts had lower blood levels of a protein called insulin-like growth factor (IGF-1), which has been strongly associated with prostate cancer.

Dr Davis, whose research was funded by the California Walnut Board, said: "Walnuts should be part of a prostate-healthy diet.

"They should be part of a balanced diet that includes lots of fruits and vegetables."

Commenting on the findings, Helen Rippon, head of research management at the The Prostate Cancer Charity, said: "This new research, which is yet to be fully peer-reviewed, does provide new clues about the development of prostate cancer and how a man's diet might help prevent the disease."

The research was presented at the annual meeting of the American Chemical Society in San Francisco.

This article was published on Tue 23 March 2010

Image © Nick Parker -

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