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Walnuts In Your Diet Help With Breast Cancer Prevention

Breast Cancer Prevention May Be In a Nutshell, Says Dr. Elaine Hardman


Updated September 17, 2009

Dr. Elaine Hardman

Dr. Elaine Hardman

Photo © Marshall University School of Medicine

Walnuts aren't just a good snack - they should become part of your anti-cancer diet. Researchers now think that having two ounces of walnuts every day may reduce your risk of developing breast cancer. But walnuts have even more health benefits to tempt you.

Walnuts Pack a Nutritional Wallop
Dr. Elaine Hardman, at the Marshall University School of Medicine has studied walnuts for 15 years. Dr. Hardman says that walnuts contain at least three nutrients that account for their anti-cancer activity. Omega-3 fatty acids, antioxidants, and phytosterols appear to be the most important components of the walnut's anti-cancer arsenal. Walnuts also contain other healthy nutrients such as natural melatonin, dietary fiber, and plant protein.

Omega-3s and Breast Cancer
While doing a lab study on mice with breast tumors, Dr. Hardman found that when the mice ate walnuts as part of their daily diet, the mice were less likely to develop breast tumors, and those that did had smaller, slower-growing tumors. Even though omega-3 fatty acids are known to have great effects on tumor growth, she thinks that omega-3s can't be isolated from walnuts, and have the same powerful effect. "It's probably different components working together to provide the benefit," said Dr. Hardman.

Roasted, Toasted, or Raw?
While we often eat walnuts that are roasted, Dr. Hardman worked with raw walnuts. So what about those walnuts that you put in your brownies? Does cooking walnuts decrease their health benefits? Dr. Hardman speculated, "My best guess is that light toasting is okay, this would not be long enough to break down the fat and change the benefit compared to what I did. As for longer cooking, I just don't know - it is possible that some of the components would be even more effective after cooking (for example, the lycopene in tomato is more active after cooking than in a raw tomato) or they could be degraded, or no difference. That is another study."

Don't Deconstruct Your Walnuts
So although walnut oil might be good for you when added to salad dressing or baked goods, the oil alone would not be sufficient to prevent or fight breast cancer. During the research study, the walnut oil by itself was not tested. However, Dr Hardman says that, "The oil would contain the omega-3 fat and lipid soluble components but would be missing other components that would be retained in the pulp." She doesn't recommend taking nutritional supplements instead of eating the natural foods. "When we start trying to take the foods apart, we rarely see the kind of [cancer-preventative] effect we get from a whole food."

Fats, Inflammation, and Cancer
Not all dietary fats are the same - some are even good for you. The omega-3 fatty acids in walnuts, fish, soy, and flaxseed can reduce your LDL cholesterol levels, lower your blood pressure, and reduce inflammation. Research about inflammation and cancer incidence is ongoing, but it appears that inflammation can influence the development of cancer. Preventing or reducing inflammation may suppress cancer growth. Omega-6 fatty acids can increase inflammation and cell proliferation, if consumed habitually in excessive amounts. Omega-6s occur in vegetable oils, meats and eggs - all too common in Western diets. Both types of fatty acids are essential for good health, but should be kept in balance.

Walnuts Are Part of Your Anticancer Action Plan
"Epidemiology data indicates that a healthy diet based on fruits, vegetables, whole grains, nuts and fish and containing little red meat or added fat would help lower the risk for many types of cancer including breast cancer," Dr. Hardman reminds us. How much of an impact does a healthy diet have? "30 to 70 percent of cancers are probably preventable with lifestyle changes," says Dr. Hardman, although experts vary in their opinions. To get the best anticancer action plan going for your life, eat a healthy diet, avoid tobacco and alcohol, do regular exercise, maintain a healthy weight, don't skip your annual mammogram, and remember to do your monthly breast self-exam.


Correspondence with Dr. W. Elaine Hardman, September 11, 2009.

Walnuts Ward Off Breast Cancer in Mice. American Association for Cancer Research 100th Annual Meeting, Denver, April 18-22, 2009. W. Elaine Hardman, PhD, associate professor of biochemistry, Marshall University School of Medicine, Huntington, W.Va.

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