Snacking on pistachio nuts may help to lower levels of so-called “bad” LDL cholesterol, suggest results of a study by researchers at Penn State University.

Professor Penny Kris-Etherton and colleagues studied the effects of three cholesterol-lowering diets, one without pistachios and two with varied levels of pistachios, on 28 adults with borderline-high LDL cholesterol levels.

The participants spent the first two weeks of the study eating the typical American diet. Following this, they spent a month eating a low-fat, pistachio-free diet. Next, for another month, they followed a healthy diet that included one daily serving of pistachio nuts. For the last month of the study they kept on following the healthy diet, but this time ate two daily servings of pistachios. All diets provided the same amount of saturated fat and cholesterol, but different amounts of unsaturated fat delivered by the pistachios.

Results showed that the participants LDL cholesterol levels fell when they ate pistachios. LDL cholesterol fell by 9% during the month that participants ate one serving of the nuts, and 12% in the month in which they ate two daily servings. The drop in cholesterol levels was not enough to put participants LDL cholesterol into the optimal range, but it was enough to get them out of the borderline-high category. To the surprise of the researchers, the low-fat diet had no effect on LDL cholesterol levels.

Gebauer SK, West SG, Kay CD, Alaupovic P, Bagshaw D, Kris-Etherton PM. Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study. Am J Clin Nutr. 2008;88:651-659.