Walnuts Improve Endothelial Function

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April 1, 2004 — Substituting walnuts for monounsaturated fatty acids

(MUFA) in the Mediterranean diet improves endothelial function,

according to the results of a randomized study published in the

April 6 issue of Circulation.

" This is the first time a whole food, not its isolated components,

has shown this beneficial effect on vascular health, " lead author

Emilio Ros, MD, from the Hospital Clinic of Barcelona, Spain, says

in a news release. " Walnuts differ from all other nuts because of

their high content of alpha-linolenic acid (ALA), a plant-based

omega-3 fatty acid, which may provide additional anti-atherogenic

properties. "

Other beneficial components in walnuts include L-arginine, folic

acid, fiber, gamma-tocopherol, and other antioxidants, which also

appear to help prevent atherosclerosis.

In this crossover-design trial, 21 men and women, aged 25 to 75

years with high cholesterol, received a cholesterol-lowering

Mediterranean diet for four weeks, followed or preceded by a four-

week diet of similar energy and fat content in which walnuts

replaced roughly 32% of the energy from monounsaturated fat. Based

on each subject's total caloric intake, the daily intake of walnuts

was approximately 1.4 to 2.3 ounces (40-65 g or 8-13 walnuts).

After each diet, subjects had fasting blood and ultrasound

measurements of brachial artery vasomotor function. Eighteen

subjects completed the study and had suitable ulrasound studies.

" Compared with the Mediterranean diet, the walnut diet increased

endothelium-dependent vasodilation (EDV) by 64% and reduced levels

of vascular cell adhesion molecule-1 by 20%, " Dr. Ros says. " In

addition, as in previous studies, the walnut diet decreased total

cholesterol and low-density lipoprotein (LDL) cholesterol [P < .05

for all comparisons]. "

Changes in EDV were inversely correlated with changes in cholesterol

to high-density lipoprotein (HDL) ratios, suggesting that the

benefit of the walnut diet was in part mediated by changes in the

lipid profile. However, the authors suggest that other factors

including ALA could be equally important.

Study limitations include the use of outpatient intervention diets,

and evaluation of only postprandial and not of fasting measurements

of endothelial function.

" The encouraging results of this study provide physicians and

patients with a powerful, yet simple, nutritional tool in their

fight against heart disease, " Dr. Ros concludes.

The California Walnut Commission, Spanish Ministry of Health, and

Fundacio Privada Catalana de Nutricio I Lipids supported this study.

Circulation. 2004;109:1609-1614