Walnuts Reduce Prostate Cancer Growth Rate

SAN FRANCISCOA diet rich in walnuts may reduce the size and growth rate of prostate cancer as well as help ward off cardiovascular disease (CVD), according to a new study presented at the 239th National Meeting of the American Chemical Society (ACS).

Walnuts should be part of a prostate-healthy diet, said lead researcher Paul Davis, Ph.D., University of California-Davis. They should be part of a balanced diet that includes lots of fruits and vegetables.

The researchers noted walnuts are a rich source of omega-3 fatty acids, gamma tocopherol (a form of vitamin E), polyphenols and antioxidants. An earlier study showed walnuts could help fight heart disease by reducing levels of endothelin, a substance that increases inflammation of blood vessels. This effect was in addition to walnuts reducing levels of bad cholesterol (low-density lipoprotein cholesterol (LDL)) in the blood.

Knowing that people with prostate cancer have elevated levels of endothelin, scientists tested whether eating walnuts could be beneficial in prostate cancer. Researchers fed lab mice genetically programmed to develop prostate cancer the equivalent of about 2.5 ounces of walnuts per dayequivalent to 14 shelled nutsfor two months. A control group of mice got the same diet except with soybean oil. The walnut-fed mice developed prostate cancers that were about 50-percent smaller than the control mice. Those cancers also grew 30-percent slower.

Walnut-fed mice had lower levels of insulin-like growth factor-1. High levels of the protein may increase the risk of developing prostate cancer in the first place. Scientists used gene-chip technology to look for changes in gene levels in the tumor itself as well as the mouses liver. They found that walnuts also had large, beneficial effects in both tumor and liver on genes that have been shown to be involved in controlling tumor growth.