The risk of Breast cancer dropped significantly in mice when their regular diet included a modest amount of walnuts, according to US research.

The study compared the effects of a typical diet and a diet containing walnuts across the lifespan: through the mother from conception through weaning, and then through eating the food directly. The amount of walnut in the test diet equates to about 2 ounces a day for humans.

During the study period, the group whose diet included walnut at both stages developed Breast cancer at less than half the rate of the group with the typical diet. In addition, the number of tumors and their sizes were significantly smaller.

"These reductions are particularly important when you consider that the mice were genetically programmed to develop cancer at a high rate," The lead author said. "We were able to reduce the risk for cancer even in the presence of a pre-existing genetic mutation."

The paper notes that dietary modification studies do not show whether benefits result from what is added to a diet or what is removed. In this case, adding healthy fat and other components meant that unhealthy fat was reduced to keep total dietary fat balanced in the mice. The author said other studies have clearly shown, however, that multiple ingredients in walnuts reduce the risk of cancer or slow its growth.

Using genetic analysis, the study found that the walnut-containing diet changed the activity of multiple genes that are relevant to Breast cancer in both mice and humans. Other testing showed that increases in omega-3 fatty acids did not fully account for the anti-cancer effect, and found that tumor growth decreased when dietary Vitamin E increased.

These findings highlight the vital role diet plays in health, as the lead author explained:

"Food is important medicine in our diet,"

"What we put into our bodies makes a big difference - it determines how the body functions, our reaction to illness and health. The simple stuff really works: eat right, get off the couch, and turn off the TV.

"The results of this study indicate that increased consumption of walnut could be part of a healthy diet and reduce risk for cancer in future generations."

Research Paper Details:

Hardman WE, Ion G, Akinsete JA, Witte TR. Dietary walnut Suppressed Mammary Gland Tumorigenesis in the C(3)1 TAg Mouse. Nutr cancer. 2011 Aug-Sep;63(6):960-70. Epub 2011 Jul 20.