Sarah K. Gebauer, a post-doctoral research associate at Pennsylvania State University, conducted a randomized, crossover design, controlled feeding experiment to test the effects of pistachios added to a heart healthy moderate-fat diet on cardiovascular disease risk factors.
The participants ate a typical American diet consisting of 35 percent total fat and 11 percent saturated fat for two weeks. They tested three diets for four weeks each, with about a two-week break between each diet.
All three diets were variations of a cholesterol-lowering diet. The diets included, as a control, a diet with no pistachios and about 25 percent total fat and 8 percent saturated fat. The pistachio enhanced diets had 10 percent to 20 percent of the energy supplied by pistachio nuts, respectively.
The study, published in the American Journal of Clinical Nutrition, found that compared to the control diet, the 20 percent pistachio diet lowered low-density lipoprotein, or LDL, the "bad" cholesterol, about 12 percent and the 10 percent energy pistachio diet lowered LDL cholesterol by 9 percent, which suggests a 9 percent to 12 percent decrease in coronary heart disease risk.