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Food, Health, and Eco-news
Walnuts Curbed Breast Cancer in Mice
We heard Professor Elaine W. Hardman, Ph.D., speak about her research on cancer and diet at the 2005 Seafood & Health conference in Washington, D.C.
She was invited to present the results of her studies in rodents, which found that omega-3s from fish oil and certain plant foods curbed tumor growth, while the omega-6 fatty acids in common vegetable oils tended to promote cancer.
Many scientists familiar with food-borne fats' impacts on human health express deep concern over Americans' relatively recent, dramatic rise in consumption of vegetable oils, and packaged or prepared foods made with them.
This shift produced a big, unprecedented, imbalance in Americans' intake of omega-3 and omega-6 fats. As famed Columbia University Professor Mehmet Oz, M.D., said, “Maintaining the right balance between omega-3 and omega-6 fats is absolutely vital for your health.”
In our 2006 article titled “Cancer: The Promising Potential of Omega-3s”, we quoted Dr. Hardman's warning about the danger of the “omega imbalance” in most Americans' diets:
“Inadvertently, we may be setting up our daughters to develop breast cancer 50 years from now.”
Elaine Hardman ... an omega-3/cancer research pioneer
We were impressed by the importance of the work being done by this little-known university researcher, and made a point of speaking with her at the 2005 Seafood & Health conference.
And we turned to her for guidance in 2006, when the authors of a just-published “meta-analysis” of existing population studies concluded that dietary omega-3 fatty acids are unlikely to prevent cancer.
As we wrote then, “The fatty acid and cancer experts we consulted consider this statement an inexplicable, unjustified interpretation of the evidence. Consequently, their thoroughly odd conclusion does a serious public disservice.”
The experts we consulted were Dr. Hardman and William E. Lands, Ph.D., who ranks high among the leading researchers in the world on the subject of dietary fatty acids and health.
Dr. Hardman and Dr. Lands concurred that most of the 38 studies examined in that meta-analysis suffered from shortcomings that rendered them virtually useless for the purpose of measuring the actual power of omega-3s to reduce specific cancer risks in humans.
Now, Dr. Hardman has published an intriguing mouse study that focused on diet and breast cancer (Hardman WE et al. 2011).
We've summarized the results below, which Dr. Hardman discusses in a YouTube video.
Mouse study finds walnuts curb cancer
Certain plants foods contain a “short-chain” omega-3 fatty acid called ALA (alpha-linolenic acid), one to 10 percent of which the body converts into the “long-chain” omega-3s (EPA and DHA) it actually needs.
Dietary ALA is not essential to human health – unless you consume little or no omega-3 HUFAs from fish or fish oil – but it does exert beneficial effects on heart and overall health.
And prior studies suggest that, like fish-form omega-3s, the omega-3 ALA found mostly in walnuts, beans, flaxseed, canola oil, and dark leafy greens (e.g., spinach, kale, and chard) may curb the growth of cancer.
The new study was led by Dr. Hardman, who is now a professor at West Virginia's Marshall University School of Medicine (Hardman WE et al. 2011).
Her team compared the effects of a typical mouse diet, and a test diet containing walnuts, across the full lifespan of the mice in the trial, which were bred to be susceptible to cancer. Both diets contained the same amounts of total calories and fat calories.
Mother mice in the test group were fed walnuts through the weaning of their pups, and then the young mice were fed walnuts directly.
The amount of walnut in the test diet equated to about 2 ounces a day for humans, on an intake-per-pound of body weight basis.
Dr. Hardman said that 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,” Hardman said. “We were able to reduce the risk for cancer even in the presence of a preexisting genetic mutation.”
And the study showed that the walnut-enriched diet changed the activity of multiple genes that influence breast cancer risk and growth in mice and humans
Omega-3s aren't the only heroes in walnuts
Other testing by Dr. Hardman's team – in which they fed mice foods containing walnuts components, but not added omega-3 ALA – showed that the increases in omega 3 ALA intake from walnuts did not fully account for the anti-cancer effect, and linked part of the decreased tumor growth to the vitamin E in walnuts.
Dr. Hardman noted that the antioxidants (polyphenols) and sterols in walnuts could help account for some of the cancer-curbing effect seen in the mice ... and that prior studies showed that these and other constituents in walnuts help curb cancer growth.
This makes sense, since walnuts have much more omega-6 fat – which, when eaten to the excess seen in the standard American diet, appears to promote cancer – than omega-3 fat.
The authors drew an encouraging conclusion: “The results of this study indicate that walnut consumption could contribute to a healthy diet to reduce risk for breast cancer.” (Hardman WE et al. 2011)
Dr. Hardman  said the findings highlight the vital role diet plays in health:
“Food is important medicine in our diet,” she said, echoing Hippocrates. “What we put into our bodies makes a big difference – it determines how the body functions, our reaction to illness and health.” (MU 2011)
Hear, hear, Dr. Hardman!
  • 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.
  • Hardman WE, Ion G. Suppression of implanted MDA-MB 231 human breast cancer growth in nude mice by dietary walnut. Nutr Cancer. 2008;60(5):666-74.
  • Hardman WE, Sun L, Short N, Cameron IL. Dietary omega-3 fatty acids and ionizing irradiation on human breast cancer xenograft growth and angiogenesis. Cancer Cell Int. 2005 Apr 28;5(1):12.
  • Hardman WE. (n-3) fatty acids and cancer therapy. J Nutr. 2004 Dec;134(12 Suppl):3427S-3430S. Review.
  • Hardman WE. Dietary canola oil suppressed growth of implanted MDA-MB 231 human breast tumors in nude mice. Nutr Cancer. 2007;57(2):177-83.
  • Hardman WE. Maternal or offspring consumption of omega 3 fatty acids to prevent breast cancer. Proc Amer Assoc Cancer Res 2005;46:3472.
  • Ion G, Akinsete JA, Hardman WE. Maternal consumption of canola oil suppressed mammary gland tumorigenesis in C3(1) TAg mice offspring. BMC Cancer. 2010 Mar 6;10:81.
  • Marshall University (MU). Breast cancer risk drops when diet includes walnuts, researchers find. September 1st, 2011. Accessed at