Based on several research studies, walnuts may be thought of as the superfood of nuts. A few years ago, studies indicated that a diet including walnuts may have a beneficial effect in reducing the risk, delaying the onset, and slowing the progression of, or preventing Alzheimer's disease.

More recently, breast surgeons Mary Legenza, M.D., of Marshall University Joan C. Edwards School of Medicine and Edwards Comprehensive Cancer Center, and James Morgan, M.D., formerly of St. Mary's Medical Center, linked walnut consumption as a contributing factor that could suppress growth and survival of breast cancers.

In their clinical trial, changes in gene expression in the surgical specimen compared to baseline were determined in each individual woman in walnut-consuming (n=5) and control groups (n=5). RNA sequencing expression profiling revealed that expression of 456 identified genes were significantly changed in the tumor related to walnut consumption.

A Penn State study, one of the first to try to uncover which parts of the walnuts help support heart health, showed that eating walnuts also may help lower blood pressure in patients at risk for cardiovascular disease. Walnuts contain alpha-linolenic acid (ALA), a plant-based omega-3, and the researchers wanted to pinpoint whether the major contributor to heart health was ALA or other bioactive components, such as polyphenols.

For this study, the researchers recruited 45 participants with overweight or obesity (ages 30 to 65 years). After a two-week run-in diet that included 12% of calories from saturated fat, participants were randomly assigned to 1 of 3 study diets, all of which included less saturated fat than the run-in diet.

The diets included one that incorporated whole walnuts, one that included the same amount of ALA and polyunsaturated fatty acids without walnuts, and one that partially substituted oleic acid for the same amount of ALA found in walnuts, without any walnuts.

All three diets substituted walnuts or vegetable oils for 5% of the saturated fat content of the run-in diet, and all participants followed each diet for six weeks.

After each diet period, participants were assessed for cardiovascular risk factors, including central systolic and diastolic blood pressure, brachial pressure, cholesterol, and arterial stiffness.

Each treatment diet had a positive effect on cardiovascular outcomes, but the diet with whole walnuts provided the greatest benefits, including lower central diastolic blood pressure, in contrast to brachial pressure.

According to Penny Kris-Etherton, distinguished professor of nutrition at Penn State, walnuts are a good substitute for saturated fat. Instead of reaching for fatty red meat or dairy products for a snack, we should consider having some skim milk and walnuts.