There has been a lot of publicity about the possible health-promoting properties of walnuts, but here’s a new one for men's health: protection against prostate cancer.

A recent study* conducted on mice at the University of California, Davis concluded that this might be the case! For the study, mice genetically engineered to develop prostate cancer were fed different diets and had tumor sizes assessed at 9, 18 and 24 weeks. They found that the mice that consumed the human equivalent of 2.8 ounces of whole walnuts daily gained weight at the same rate as mice fed a soybean oil diet formulated to match the nutrients, fat levels and fatty acid profiles of the walnut diet. At 18 weeks, however, the tumor weight of the walnut-fed group was approximately half that of the mice consuming the soybean oil diet. Overall, the rate of tumor growth was 28 percent lower in the walnut-fed mice.

Men have traditionally been encouraged to follow a low-fat diet to reduce their risk of prostate cancer or to slow the growth of existing cancers. But Paul Davis, a nutritionist and the lead author of the study believes there is now reason to rethink this recommendation and hints that while more research still needs to be done (on humans), the initial studies performed with mice are promising.

“If additional research determines that walnuts have the same effect in men as they do in mice, adhering to a diet that excludes walnuts to lower fat would mean that prostate cancer patients could miss out on the beneficial effects of walnuts,” says Davis.

Prostate cancer is common. One in six American men will be diagnosed with it in their lifetime, most commonly in later life. But relatively few -- one in 36 -- will die from the disease because most tumors do not spread beyond the local site, according to the National Cancer Institute.

"These characteristics of prostate cancer make adding walnuts to a diet attractive as part of prostate cancer prevention," Davis said.