Walnuts, Walnut Oil Lowers Blood Pressure

UNIVERSITY PARK, Pa.New findings from Penn State researchers suggests a diet rich in walnuts and walnut oil helps a body cope with stress by lowering both resting blood pressure and blood pressure responses to stress.

The study, published in the Journal of the American College of Nutrition, examined walnuts and walnut oils, which contain polyunsaturated fats, influence blood pressure at rest and under stress. Previous studies have shown that omega-3 fatty acidslike the alpha linolenic acid found in walnuts and flax seedscan reduce low density lipoproteins (LDL) and may 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," said 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."

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

"This is the first study to show that walnuts and walnut oil reduce blood pressure during stress," said 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."

A subset of the participants also underwent a vascular ultrasound in order to measure artery dilation. Results showed that adding flax oil to the walnut diet significantly improved this test of vascular health. The flax plus walnuts diet also lowered c-reactive protein, indicating an anti-inflammatory effect. West said that also may reduce risk of cardiovascular disease.