Walnuts Improve Stress Reaction

A diet rich in walnuts and walnut oil may prepare the body to deal better with stress, according to a team of Penn State researchers who looked at how these foods, which contain polyunsaturated fats, influence blood pressure at rest and under stress.

Previous studies have shown that omega-3 fatty acids -- like the alpha linolenic acid found in walnuts and flax seeds -- can reduce low-density lipoproteins, the so-called bad cholesterol. These foods may also reduce c-reactive protein and other markers of inflammation.

"People who show an exaggerated biological response to stress are at higher risk of heart disease," says Sheila G. West, associate professor of biobehavioral health. "We wanted to find out if omega 3-fatty acids from plant sources would blunt cardiovascular responses to stress."

The researchers studied 22 healthy adults with elevated LDL cholesterol. All meals and snacks were provided during three diet periods of six weeks each.

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. Participants gave a speech or immersed their foot in cold water as a stressor. Adding flax seed oil to the walnut diet did not further lower blood pressure. They report their findings in the current issue of the Journal of the American College of Nutrition.

"This is the first study to show that walnuts and walnut oil reduce blood pressure during stress," says West. "This is important because we can't avoid all of the stressors in our daily lives. This study shows that a dietary change could help our bodies better respond to stress."