The research team put the young men on three successive diets: a healthy heart plan with 25 percent of calories from fat and 8 percent saturated fat; a diet with 30 percent of calories from fat and 8 percent saturated fat plus 1.5 ounces of pistachios daily; or a diet with 34 percent of calories from fat and eight percent saturated fat plus three ounces of pistachios.

At the end of four weeks on each of the three diets, the researchers checked the participants’ blood pressure, assessed the elasticity of their blood vessels when at rest, and gave them two stress tests.

They found that the 1.5-ounce pistachio diet lowered systolic (the top number) blood pressure by 4.8 mm of mercury; the three ounce pistachio diet reduced systolic blood pressure by 2.4 mm of mercury and also relaxed the arteries, a beneficial change that reduces the heart’s overall workload.

The study was sponsored by the California Pistachio Commission and was reported at an Experimental Biology conference in April 2007.

True, nuts such as pistachios are generally high in fat, but most of them contain monounsaturated fat that is good for the heart. In fact, eaten in moderation, nuts of all kinds appear to lower your risk of heart disease and heart attack.

The ongoing Nurses Health Study at Brigham and Women’s Hospital in Boston and the Harvard School of Public Health, which is monitoring the health of 86,000 nurses, found that those who ate more than five ounces of nuts per week (about the total you would get by eating a single airline packet daily) had one third fewer heart attacks than those who rarely or never ate nuts. Other studies have supported these findings.