Although studies in the past have established the health benefits of a walnut-enriched diet in terms of breast cancer development, not a lot of research has been launched into what other forms of cancer it could prevent. A research team from the School of Medicine at The University of Texas Health Science Center San Antonio has now added prostate cancer prevention to the walnut's growing list of health benefits.

"The data to date suggest that using walnuts on a regular basis in the diet may be beneficial to defer, prevent or delay some types of cancer, including breast and prostate," said Russel Reiter, Ph.D., the study's senior author and professor of cellular and structural biology at the Health Science Center.

Reiter and his colleagues set up two animal control groups, including 16 mice that were fed a diet complete with walnuts ground up into a powder so they wouldn't just eat the nuts and a control group of 32 mice that were fed a diet with no walnuts.

"The walnut portion was not a large percentage of the diet," Reiter said. "It was the equivalent to a human eating about 2 ounces, or two handfuls, a day, which is not a lot of walnuts."

Results of the analysis showed that only three of the mice who were fed a walnut-enriched diet developed prostate tumors compared to 14 of the mice who weren't fed walnuts. Researchers also noted that walnut-fed mice displayed prostate tumors one-fourth the size of those featured in mice who were not fed walnuts.

"We found the results to be stunning because there were so few tumors in animals consuming the walnuts and these tumors grew much more slowly than in the other animals," Reiter added.

"We were absolutely surprised by how highly effective the walnut diet was in terms of inhibition of human prostate cancer."

The study's co-author W. Elaine Hardman, Ph.D., of the Joan C. Edwards School of Medicine at Marshall University, was also involved with a study back in 2011 that examined the effects of walnut-rich diets on breast cancer.

"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," said Hardman.

"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."

Source: Tan D, Manchester L, Korkmaz A, Fuentes-Broto L, Hardman E, Reiter R. A Walnut-Enriched Diet Reduces the Growth of LNCaP Human Prostate Cancer Xenografts in Nude Mice. Cancer Investigation. 2013.