Walnuts may help combat stressAnd lower blood pressure
Eating walnuts may help the body cope better with stress, as well as lowering blood pressure, scientists claim.
Past studies have shown that omega-3 fatty acids can reduce low density lipoproteins (LDL) or "bad cholesterol" in the blood, and help reduce the risk of heart disease.
So U.S scientists looked at how eating walnuts, which contain alpha linolenic acid, affect blood pressure during stressful situations.
"People who show an exaggerated biological response to stress are at higher risk of heart disease," said Professor Sheila West, from Penn State University. "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 raised LDL cholesterol levels. Each of the participants tried three six week diets; one without walnuts, one with walnuts and walnut oil and a third with walnuts, walnut oil and flaxseed oil.
The walnuts, walnut oil, and flaxseed oil were either mixed into the participants food or eaten as a snack. An average daily serving of nuts consisted of 18 halves or 9 whole walnuts.
After each diet the volunteers underwent stress tests; they had to either give a speech or immerse a foot in ice-cold water. Blood pressure was monitored throughout the tests.
The results showed that the average diastolic blood pressure - the "bottom number," or the pressure in the arteries when the heart is resting - was significantly reduced during the diets containing walnuts and walnut oil.
"These results are in agreement with several recent studies showing that walnuts can reduce cholesterol and blood pressure," said Professor West.
"This work suggests that blood pressure is also reduced when a person is exposed to stress in their daily life."
Adding flax seed oil - a richer source of omega-3 fatty acids- to the walnut diet did not further lower blood pressure. The study did not look at how flaxseed oil alone affected blood pressure.
"This is the first study to show that walnuts and walnut oil reduce blood pressure during stress," continued Professor 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."
The findings are published in the Journal of the American College of Nutrition.
This article was published on Mon 4 October 2010
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