Walnuts are rich in compounds including vitamin E, ellagic acid, flavonoids, and melatonin, all of which confer antioxidant properties.  As well, walnuts are a good source of alpha linolenic acid, and thus are an important plant-based source of omega-3 fatty acid.  Emerging research suggests a number of potentially beneficial health effects of consuming walnuts.

Yale University (Connecticut, USA) researchers report improved function of the blood vessel lining and reduced cholesterol levels in diabetics who consume walnuts daily.  In a study that enrolled 14 women and 10 men, median age 58 years, with type 2 diabetes, some subjects were assigned to consume 56 grams of walnuts daily, for 8 weeks. At the conclusion of the study period, the researchers found significant improvements in the function of the blood vessel lining (endothelium), with blood flow improved by 2.2% in the group that consumed walnuts (as compared to 1.2% in the non- supplemented group).  The walnut-enriched diet also increased lowered serum total cholesterol and low-density lipoprotein.  The study authors conclude that: "A walnut-enriched … diet improves endothelium-dependent vasodilatation in type 2 diabetics, suggesting a potential reduction in overall cardiac risk.”

A team from the University of California/Davis (California, USA) has discovered that walnut consumption slows prostate cancer progression, in an animal model of the disease.  Mice that had been genetically programmed to get prostate cancer were fed the human equivalent of 2.4 ounces of walnuts per day. After 18 weeks, the animals exhibited significantly smaller, slower-growing prostate tumors, as compared to mice consuming the same diet with an equal amount of fat, but not from walnuts. The team also found that not only was prostate cancer growth reduced by 30 to 40%, but the mice had lower blood levels of a protein marker of prostate cancer.

New York State Institute for Basic Research in Developmental Disabilities (New York, USA) researchers studied the effect of dietary supplementation of walnuts on the memory, anxiety and learning skills, in a mouse model of Alzheimer’s Disease.  Among those mice fed walnuts, mental skills were preserved; as compared to the Alzheimer-model mice that were not fed the nuts who suffered a dramatic loss in learning, memory and physical and emotional control.  Positing that walnuts helped to destroy harmful free radical chemicals that are implicated in dementia, the study authors conclude that:  “Our results suggest that dietary supplementation of walnuts may have beneficial effect in reducing the risk, delaying the onset or slowing the progression of Alzheimer’s disease."

Walnuts also improve the stress response.  A team from Penn State University (Pennsylvania, USA) studied 22 healthy adults with elevated LDL (low-density lipoprotein) cholesterol, supplying each subject with meal and snack foods during three diet periods of six weeks each.  The three diet periods consisted of:  first diet as an "average" American diet – a diet without nuts that reflects what the typical person in the U.S. consumes each day;  the second diet included 1.3 ounces of walnuts and a tablespoon of walnut oil substituted for some of the fat and protein in the average American diet; and the third diet was comprised of walnuts, walnut oil and 1.5 tablespoons of flaxseed oil. The researchers found that including walnuts and walnut oil in the diet lowered both resting blood pressure and blood pressure responses to stress in the laboratory. Results also showed that average diastolic blood pressure was significantly reduced during the diets containing walnuts and walnut oil. The study authors conclude that: This study shows that a dietary change could help our bodies better respond to stress."

Plant sources of polyunsaturated omega-3 fatty acids such as walnuts are highlighted in the new USDA MyPyramid food construct, encouraging Americans to consume more polyunsaturated fat (and less saturated and trans fat) in order to achieve a healthy diet. 

Learn more at: http://www.mypyramidtracker.gov/