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||Last Updated: Nov 12th, 2006 - 20:38:00
Walnuts may prove to be more beneficial to the health of the arteries and the heart than olive oil to consumers following a Mediterranean-type diet, according to a small Spanish study. However the researchers cautioned that eating walnuts did not mean that they could indulge in any kind of foods.
Walnuts are a rich source of omega-3 alpha-linolenic acid (ALA). Omega-3 fatty acids are known to prevent many types of diseases including cancer. In the current study, researchers tried to test the effect of walnuts and olive oil on arteries after the consumption of a fatty meal.
The researchers from the Universitat Autonoma de Barcelona enrolled 12 healthy men and women as well as 12 patients with high cholesterol for the study. The subjects were randomly assigned a high-fat meal containing 80 g fat, 35 per cent of which was saturated fat. The meal was later supplemented with 40 grams of walnuts or 25 grams of olive oil.
The participants followed their diet for a week after which they were switched over to the opposite diet. That is, the group consuming walnuts were given olive oil and vice versa.
Researchers tabulated the blood vessel activity following the fatty meal and measured lipoprotein levels, markers of oxidative stress, and plasma levels of asymmetric dimethylarginine (ADMA). The latter is a breakdown product of protein metabolism and has the ability to interfere with the production of nitric oxide in the body.
Nitric oxide is important since it mediates the constriction and dilation of smooth muscles. This in turn increases the blood flow.
In the current study, researchers found eating a walnut-supplemented meal increased a parameter called flow-mediated dilation (FMD), which denotes the blood flow in the arm. Researchers reported a 24 percent increase in blood flow in the walnut group. However, FMD seemed to actually decrease by 36 percent in the olive oil group.
“The fact that a single walnut meal positively affects postprandial vasoactivity further supports the beneficial effects of walnuts on cardiovascular risk,” wrote lead author Berenice Cortés in the online edition of the Journal of the American College of Cardiology.
Mediterranean diet, which seems to rely exclusively on cereals, fruits, nuts, legumes and whole grains, fish and olive oil, has been projected as a life-lengthening diet. Patrons of the diet say that it protects the heart as well.
The presence of fish and olive oil were believed to confer the cardio-protective effects. However, the present study says that walnuts also play an important part in keeping the heart healthy.
“Recently, [other researchers] reported increased FMD in diabetic patients after meals enriched with either marine n-3 PUFA or ALA, thus supporting the beneficial role of ALA-rich walnuts on endothelial," the researchers added.
Walnuts, recognized as brain foods are rich in ALA and are known to reduce the risk of heart disease, cancer, stroke, diabetes, high blood pressure, obesity and clinical depression. Walnuts are also known to decrease the levels of inflammation. Walnuts have earned the sobriquet of a "SuperFood."
The study was funded by the California Walnut Commission and the Spanish Ministry of Health.
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