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Walnut and parsley salad.
Walnuts, like those featured in this parsley and walnut salad, provide fiber as well as minerals and other nutrients. Image courtesy of the Walnut Marketing Board.

Walnuts' Potential New Link to Heart Health Reported

By Marcia Wood
July 31, 2006

Walnuts, already shown in some studies to reduce "bad" (LDL) cholesterol, may have yet another way of enhancing cardiovascular health.

University of California-Davis (UC-Davis) scientists and their Agricultural Research Service (ARS) and University of Padova (Italy) co-investigators have found that laboratory hamsters that ate feed containing walnuts had significantly lower levels of a natural chemical called endothelin. The compound causes inflammation of arteries and growth of sticky deposits—called plaque—on blood vessels. These conditions contribute to heart disease, the leading cause of death in the United States.

In this six-and-one-half-month study of about 100 hamsters, walnuts apparently suppressed heart artery endothelin. Walnuts had that effect at all levels tested, which were the equivalent of a human eating from three to eight handfuls of walnuts a day.

For the study, scientists used English walnuts, the kind sold in supermarkets nationwide, adding them to the hamsters' meals as a finely ground powder.

Research chemist Wallace H. Yokoyama, with the ARS Western Regional Research Center in Albany, Calif., collaborated in the study, which was led by research nutritionist Paul A. Davis at UC-Davis.

The study, reported earlier this year in the Journal of Nutrition, builds upon observations by researchers elsewhere that eating walnuts may affect blood vessels directly. The California study is the first to demonstrate this by showing walnuts' ability to suppress artery endothelin in lab animals. Additional studies are needed to determine if this beneficial effect occurs in people who eat a moderate amount of walnuts.

Walnuts are a good source of fiber, healthful fatty acids and minerals. They can be sprinkled on breakfast cereal, tossed with crisp greens for a lunch or dinner salad, or simply eaten out of hand as a snack.

ARS is the U.S. Department of Agriculture's chief scientific research agency.