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Pistachio nuts are the product of the pistachio tree (Pistacia vera), which is native to the Middle East and Mediterranean region (e.g., Syria, Iran, Turkey, Greece, Pakistan, India). Today the pistachio tree is also grown and cultivated in other areas of the world, including the United States. The pistachio tree belongs to the Anacardiaceae family, which includes as its members the mango, cashew, poison ivy, and sumac.
Prostate Health Benefits
Pistachio nuts have demonstrated an ability to improve erectile function, reflected in a significant improvement on the International Index of Erectile Function (IIEF) scores. The IIEF measures erectile function, satisfaction with sexual intercourse, orgasmic function, sexual desire, and overall satisfaction. The study involved 17 married men who had had erectile dysfunction for at least one year. Before and after the three-week study, all the men completed the IIEF. During the three weeks, each day all the men consumed 100 grams of pistachios during lunch.
At the end of the study, the IIEF scores had increased significantly, from an average of 36 before the diet up to 54.2 after the diet. The men also experienced significant reductions in total cholesterol and low-density lipoprotein (LDL) cholesterol along with a significant increase in high-density lipoprotein (HDL) levels, as well as a significant decrease in testosterone levels.
Although the reason why pistachios may help erectile function is not known, the authors note that the nuts are a very good source of the amino acid arginine, which appears to help maintain flexible arteries and enhance blood circulation by improving the ability to nitric oxide to relax blood vessels. This action can improve erectile function. The reduction in testosterone may be associated with phytosterol, a phytonutrient in pistachios that has been shown in animal studies to reduce testosterone levels. (Aldemir 2011)
Other Health Benefits
In July 2003, the Food and Drug Administration issued a statement concerning nuts, including pistachios, noting that “Scientific evidence suggest but does not prove that eating 1.5 ounces (42.5 g) per day of most nuts, such as pistachios, as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.” (FDA 2003)
Pistachios have also demonstrated an ability to lower total cholesterol while boosting the “good” high-density lipoprotein (HDL) cholesterol. In a study published in Nutrition, Metabolism and Cardiovascular Disease, researchers from Harran University in Turkey randomly assigned 44 healthy volunteers (average age, 33 years; 24 men, 20 women) to a regular diet or to a test diet with 20 percent of the daily calorie intake from pistachios.
After three weeks on the diets, the volunteers in the pistachio group had a 12 percent decline in total cholesterol levels compared with baseline, and a 26 percent increase in their HDL levels. In addition, the ratio of total cholesterol to HDL, which is a specific lipid risk factor for cardiovascular disease, declined by 21 percent. The volunteers who consumed a regular diet did not have any significant changes in their cholesterol levels.
The scientists suggested pistachios may help improve cholesterol levels because they are high in monounsaturated fat and/or their high concentration of phytosterols. Pistachios are also a rich source of vitamin A and vitamin E (gamma-tocopherol). (Kocyigit 2006)
In 2010, a study from Penn State University reported that pistachio nuts, when included as part of a healthy diet, can raise the levels of antioxidants in the blood of adults who have high cholesterol. The authors of the study, which appeared in the Journal of Nutrition, stated that “pistachios are high in lutein, beta-carotene and gamma-tocopherol relative to other nuts; however, studies of the effects of pistachios on oxidative status are lacking.”
To determine the antioxidant potency of pistachios, the researchers conducted a controlled study to test the impact of pistachios on antioxidant levels when they were added to a heart-healthy moderate-fat diet. The investigators tested three diet variations: one contained no pistachios, one included 1.5 ounces of pistachios, and one included 3 ounces of pistachios. Individuals who participated in either of the pistachio diets had higher blood serum levels of beta-carotene, lutein, and gamma-tocopherol than did subjects in the control diet. Subjects who ate pistachios also showed a decrease in LDL levels. (Kay 2010)
Side Effects
Pistachios contain a substance called urushiol, an irritant that can cause an allergic reaction in some people. (Mabberley 1993) The pistachio nut also has several proteins that may trigger hypersensitivity reactions in a small number of people. (Fernandez 1995)
Eating Pistachios
The pistachio tree produces nuts with kernels that can be eaten fresh or roasted, included in salads, or used in desserts. For health benefits, the preferred forms are fresh or dry roasted pistachios, as a snack or added to a fruit or vegetable salad. The amounts used in studies have ranged from 1 to about 3.5 ounces. Men who need to watch their weight should make allowances for the addition of pistachios to their diet.
References
Aldemir M et al. Pistachio diet improves erectile function parameters and serum lipid profiles in patients with erectile dysfunction. Intl J Impotence Res 2011; 23:32-38
FDA. Office of Nutritional Products, Labeling and Dietary Supplements (2003-07-23). “Qualified Health Claims: Letter of Enforcement Discretion – Nuts and Coronary Heart Disease (Docket No 02P-0505)”. Center for Food Safety and Applied Nutrition.
Fernandez C et al. Allergy to pistachio: crossreactivity between pistachio nut and other Anacardiaceae. Clin Exp Allergy 1995 Dec; 25(12): 1254-59
Kay CD et al. Pistachios increase serum antioxidants and lower serum oxidized-LDL in hypercholesterolemic adults. J Nutr 2010 Jun; 140(6): 1093-98
Kocyigit A et al. Effects of pistachio nuts consumption on plasma lipid profile and oxidative status in healthy volunteers. Nutr Metab Cardiovasc Dis 2006 Apr; 16(3): 202-9
Mabberley DJ. The Plant Book. Cambridge: Cambridge University Press, 1993; 27.
