The health benefits of pistachios are similar to those of other nuts that provide a high content of monounsaturated fat and arginine. Additionally, pistachios are a very good source of both magnesium and potassium, two minerals that protect against high blood pressure.
Given their heart-healthy constituents, it's not surprising that two recent clinical research trials have demonstrated that including pistachios regularly in the diet significantly improves lipid profiles in humans with both normal and moderately elevated blood levels of cholesterol. In one study, pistachios were substituted for 20 percent of the daily caloric intake in ten patients with moderately elevated blood cholesterol levels who followed a traditional American diet (35 to 39 percent of their calories from fat). After three weeks, the result was a significant decrease in both total and LDL (bad) cholesterol levels, plus an increase in levels of beneficial HDL cholesterol. In the other study, including 2 to 3.5 ounces of pistachios in a low-fat diet (30 percent calories from fat) produced a 5 to 12 percent lowering of total cholesterol and a 10 to 15 percent drop in LDL cholesterol.
In addition to their healthy fats and sterols, pistachios contain a compound with anti-inflammatory effects. In a 2001 animal study, this compound, oleanolic acid, was found to alleviate dermatitis because of its ability to inhibit the production of the proinflammatory agent leukotriene B4.
Another recent study evaluated the long held belief in Jordanian folk medicine that pistachios are an effective treatment for jaundice. When intoxicated rats were given a dose of 4 milliliters per kilogram of body weight of a water extract of pistachio, the liver-damaging activity of three enzymes -- alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase -- was significantly reduced, along with bilirubin levels. (Bilirubin is a yellowish pigment in bile whose accumulation is a primary symptom of jaundice.) Thus it appears that the practice of using pistachios as a folk remedy for jaundice has merit.