Pistachio

Scientific Name(s): Pistacia vera L.
Common Name(s): Akbari, Pistachio

Medically reviewed by Drugs.com. Last updated on Jan 1, 2023.

Clinical Overview

Use

Pistachio nut consumption has been studied for effects on aging, cardiometabolic risk factors, diabetes, gut microbiota, hypercholesterolemia, and multiple sclerosis (MS). However, clinical trial data are lacking to recommend use for any indication.

Dosing

Quantities of pistachios consumed (often as part of a diet) and treatment durations have varied among studies.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Most adverse reactions are associated with hypersensitivity to the plant or with allergic reactions.

Toxicology

No data.

Scientific Family

• Anacardiaceae (sumac)

Botany

P. vera is a native of Central and West Asia, and is also distributed throughout the Mediterranean basin. It is grown in the United States (ie, California, Arizona) and other countries where it has been introduced.(Alma 2004, USDA 2022) A related species is Pistacia lentiscus, commonly known as mastic.(USDA 2022)

P. vera is a spreading, partially deciduous tree that grows up to 10 m in height. Leaves occur in 1 to 5 pairs of thick, oval leaflets. Tiny, brown-green flowers give way to clusters of the oblong pistachio kernel.(Alma 2004, Gentile 2007) The exudate of the plant forms a gum that is traditionally used for medicinal purposes.(Alma 2004)

History

Records of consumption of pistachios as a food date to 7000 BC.(Tsokou 2007) Pistachio is commonly used for flavoring candy and cakes, and in toothpaste and dentistry.(Alma 2004, Tsoukou 2007)

Traditional uses include treatment of toothache and other periodontal conditions, blood clotting, dyspepsia, asthma, jaundice, diarrhea, and renal stones, and as an anti-inflammatory, antibacterial, and antiviral agent.(Alma 2004, Bozorgi 2013, Tsokou 2007)

Pistachio gum has traditionally been used for respiratory diseases (anti-infective); for its anti-inflammatory effects in stomach conditions, hemorrhoids, and asthma; and as a lip balm. It is also used as a protectant for glass, porcelain, bone, wood, and metal objects.(Alma 2004, Borzorgi 2013, Orhan 2006b)

Chemistry

The fruits of pistachio are high in protein, oil, and vitamin E compared with hazelnut. Unsalted, pistachio nuts are high in potassium and low in sodium. The kernels are rich in linoleic and linolenic fatty acids.(Ozcelik 2005)

The essential oil of the leaves contains alpha-pinene (30%), terpinolene (18%), and bornyl acetate (11%), while the essential oil of the fruits contains alpha-pinene (55%), terpinolene (approximately 30%), limonene, 3-carene, and beta-pinene (approximately 1% each), which is similar to mastic gum oil. Alpha-pinene and terpinolene have shown antibacterial and antifungal activity, while terpinolene has some antioxidant activity.(Tsokou 2007) Reviews of the chemical composition are available.(Bozorgi 2013, Rauf 2017)

Vitamin E alpha- and gamma-tocopherol, vitamin C, proanthocyanidins, transresveratrol, isoflavones, daidzein, and genistein have been identified in the edible nut.(Gentile 2007, Tsokou 2007) The antioxidant activity is substantially affected by toasting.(Gentile 2007)

The essential oil of the gum contains mostly monoterpene hydrocarbons, oxygenated monoterpenes, and diterpenes, including alpha-pinene (75%), beta-pinene (9%), transverbenol (3%), and camphene, limonene, and pinocarveol (approximately 1% each).(Alma 2004)

Uses and Pharmacology

Efficacy may be affected by the geographical source of the nuts and degree of processing.(Alma 2004, Orhan 2006a)

Aging

Clinical data

In a randomized, crossover trial of prediabetic patients with a body mass index (BMI) no more than 35 kg/m² and fasting plasma glucose concentration between 100 and 125 mg/dL (N=54 randomized; 49 patients included for analysis), consumption of a pistachio-rich diet (57 g/day of pistachios) for 4 months significantly reduced oxidative DNA damage (P=0.009) as well as upregulated genes related to telomere maintenance (P<0.05) but did not significantly impact telomere length compared with the 4-month nut-free control diet phase. However, a significant inverse correlation was observed between telomere length and changes in insulin resistance as assessed by homeostatic model assessment of insulin resistance (HOMA-IR) (P=0.021), and a significant positive correlation was noted between telomere length and changes in telomerase gene expression (P=0.044). In patients in whom telomere gene expression was upregulated during the pistachio phase, fasting plasma glucose and degree of HOMA-IR was significantly reduced compared with those in whom telomerase was downregulated (P<0.05).(Canudas 2019)

Anti-inflammatory effects

Animal data

In an experiment in mice, extracts from the fruit, leaves, and branch parts, as well as the exudates, were evaluated for anti-inflammatory and antinociceptive effects. The plant part extracts were ineffective, but an extract of the gum showed a dose-dependent effect on induced abdominal contractions and induced paw edema.(Borzorgi 2013, Orhan 2006b)

Clinical data

Topical application from pistachio skin and seeds reduced ultraviolet-B–induced skin erythema in human volunteers. An additional antioxidant effect was also suggested based on the phenolic content of the seed.(Martorana 2013)

Antimicrobial activity

In vitro data

In vitro studies show little action against human bacterial pathogens, but antifungal activity comparable with nystatin has been demonstrated by plant extracts and the essential oil of the gum.(Alma 2004, Ozcelik 2005)

The skin of the woody shell, fresh kernels, and unripe seeds collected from southeastern Turkey showed antiviral action against herpes simplex virus when compared with acyclovir.(Ozcelik 2005) Extracts of the branches of the plant showed activity against Leishmania donovani, while an extract from the leaves was active against Plasmodium falciparum.(Orhan 2006a)

Cardiometabolic risk factors

Clinical data

Pooled data from 11 randomized controlled trials (N=506; mean of 46 patients per study) showed that pistachio consumption was associated with a significant mean weight increase of 0.19 kg (no heterogeneity) and significant mean decreases in fasting blood glucose (−3.73 mg/dL), total cholesterol/HDL ratio (−0.46), LDL/HDL ratio (−0.24), glycosolated hemoglobin (HbA_1c) (−0.14%), insulin (−2.43 milliunits/mL), systolic blood pressure (−3.1 mm Hg), and malondialdehyde (−0.36 mmol/L). Heterogeneity was significant for the majority of comparisons. No overall effects on waist circumference, LDL, HDL, triglycerides, total cholesterol, insulin resistance, diastolic blood pressure, C-reactive protein, or flow-mediated dilatation were observed. The overall quality of the trials was good and the mean duration of intervention was approximately 10 weeks (range, 3 to 24 weeks). Healthy participants (n=130) were studied in 3 trials whereas the remaining 8 enrolled patients with MS (n=150), diabetes (n=104), dyslipidemia (n=70), or obesity (n=52).(Ghanavati 2020)

Data were pooled from 4 randomized controlled trials (N=178) evaluating the effects of pistachio on endothelial reactivity in adults who were mildly dyslipidemic, normolipidemic, or with well-controlled type 2 diabetes. Results reflected a significant effect of pistachio consumption on brachial artery diameter (weighted mean difference, +0.04%; 95% CI, 0.03% to 0.06%; P<0.001) but not on flow-mediated dilatation. Two of the studies were of crossover design and 2 were parallel; the duration of studies ranged from 4 to 12 weeks; and quantities of pistachios consumed varied among the studies.(Fogacci 2019)

Diabetes and metabolic syndrome

Clinical data

A systematic review identified 6 randomized controlled trials that assessed the effects of pistachio nut consumption in patients with type 2 diabetes or at risk for type 2 diabetes (ie, Parkinson disease, MS). Half of the studies were rated as poor quality and study population sizes were not reported. Reported dosing ranged from 42 to 70 g/day; duration of interventions ranged from 4 to 24 weeks. Meta-analyses of pooled data revealed a significant reduction in fasting blood glucose with pistachios compared with controls overall (odds ratio [OR], 1.7 [95% CI, 1.2 to 2.4]; P=0.002; no heterogeneity; 5 studies) and in the subgroup of patients with Parkinson disease (OR, 2.5 [95% CI, 1.3 to 5]; P=0.01; 1 study) but not in the diabetes or MS subgroups. No significant difference was found for HbA_1c; however, 1 of the 4 studies reporting this outcome was only 4 weeks in duration, which is insufficient to determine HbA_1c changes. Insulin resistance as measured by HOMA-IR was also significantly improved with pistachios compared with controls overall (OR, 1.5 [95% CI, 1 to 2.4]; P=0.043; no heterogeneity; 3 studies) as well as in the Parkinson disease subgroup (OR, 2.1 [95% CI, 1.1 to 4.3]; P=0.033; 1 study) but not the diabetes subgroup. In contrast, no effect was observed on fasting plasma insulin.(Nowrouzi-Sohrabi 2020) Pistachio consumption was associated with significant mean decreases in fasting blood glucose (−3.73 mg/dL) and insulin (−2.43 milliunits/mL) in a meta-analysis of 11 randomized controlled trials enrolling patients with cardiometabolic risk factors (N=506; mean of 46 patients per study). No overall effect was found on triglycerides or insulin resistance. Only a portion of participants had diabetes (n=104); the majority had MS (n=150), followed by healthy participants (n=130) and those with dyslipidemia (n=70) or obesity (n=52). Heterogeneity was significant for the majority of comparisons.(Ghanavati 2020)

GI effects

Clinical data

A systematic review exploring the effects of nuts on gut microbiota, gut function, and gut symptoms identified 1 study that assessed pistachios. In healthy adults enrolled in a crossover controlled trial (N=34), consumption of 42 g/day or 84 g/day of pistachio nuts for 18 days decreased the number of lactic acid fecal bacteria but had no effect on Bifidobacteria, diversity of taxa within a sample, or predominant fecal bacteria phyla compared with controls. Pistachios were found to have a greater effect on diversity of taxa between samples than almonds.(Creedon 2020)

Hypercholesterolemia

Animal and in vitro data

Animal and in vitro experiments suggest an antioxidant action may be responsible for the serum lipid effects observed in clinical trials.(Aksoy 2007, Gentile 2007) A 60% loss in antioxidant action by roasting is suggested to be due to a loss in total phenol content, with isoflavones being affected by heat.(Gentile 2007)

Clinical data

Studies among healthy volunteers(Kocyigit 2006) and in individuals with moderate hypercholesterolemia(Edwards 1999, Gebauer 2008, Sheridan 2007) have shown that inclusion of unroasted pistachio nuts in the diet affects lipid profiles. Decreases were observed for mean plasma total cholesterol and total cholesterol/HDL and LDL/HDL ratios; increased HDL levels were reported. No changes were found for triglycerides or LDL levels. No change in blood pressure or body weight was observed.(Edwards 1999, Gebauer 2008, Kocyigit 2006, Sheridan 2007) One trial evaluated changes in apolipoproteins and reported a decrease in apolipoprotein B.(Gebauer 2008)

Effects on lipid profiles were demonstrated after 2 doses of pistachios in 1 trial,(Gebauer 2008) and other studies evaluated effects after 3 weeks of supplementation.(Edwards 1999, Kocyigit 2006, Sheridan 2007)

Data pooled from 11 randomized controlled trials (N=506; mean of 46 patients per study) found that pistachio consumption was associated with significant mean decreases in the ratios of total cholesterol/HDL (−0.46) and LDL/HDL (−0.24). No overall effects were found on LDL, HDL, triglycerides, or total cholesterol. Heterogeneity was significant for the majority of comparisons. The mean duration of intervention was approximately 10 weeks (range, 3 to 24 weeks). Only a small portion of participants had dyslipidemia (n=70); the majority had MS (n=150), followed by healthy participants (n=130) and those with diabetes (n=104) or obesity (n=52).(Ghanavati 2020)

Melanogenesis effects

Animal and in vitro data

Tyrosinase, the key enzyme in melanin biosynthesis, was strongly and dose-dependently inhibited by a pistachio hull extract in vitro. This potential antimelanogenic activity was confirmed in an animal model in which the extract demonstrated a significant reduction in melanogenic activity (P<0.001) compared with the negative control, without toxicity.(Smeriglio 2021)

Multiple sclerosis

Clinical data

Data from 28 women with symptomatic relapsing-remitting MS who completed a phase 1, double-blind, randomized, placebo-controlled trial (N=39) indicated significant improvements in the mean number of relapses (2 vs 3.8 with placebo), Expanded Disability Status Scale scores (2.5 vs 3.8), and T2 lesions (8 vs 12), respectively, in patients given 5 mL/day of 10% peglated nanoliposome of pistachio unsaturated oils for 24 weeks compared with placebo (P<0.05 for each). The effect was determined to be a result of anti-inflammatory effects of the pistachio oil treatment, as significant decreases in Th2 cytokines (ie, IL-4, IL-5, IL-10) and significant increases in interferon-gamma and IL-17 were observed (P<0.05). This anti-inflammatory profile is a positive signal and has been associated with a good recovery process.(Hassanshahi 2022)

Weight control and dietary effects

Clinical data

Data from approximately 2,000 participants in 2 meta-analyses reflect similar small changes in body weight (−0.22 kg and 0.19 kg), waist circumference (0.76 cm and 0.67 cm), and BMI (−0.18 kg/m² and −0.21 kg/m²) with pistachio nut consumption compared with nut-free controls. The statistical significance of these results was equivocal, and heterogeneity was very high among the majority of comparisons.(Ghanavati 2020, Xia 2020)

A systematic review of randomized controlled trials identified 11 studies (N=1,593) that assessed the effects of pistachio nut consumption on weight parameters (ie, body weight, BMI, waist circumference). Of the 11 studies, 5 were crossover and 6 were parallel-controlled; 3 trials included healthy adults whereas the other 8 included patients with diabetes, hypercholesterolemia, or obesity. Pooled data indicated that pistachio intake had an insignificant effect on body weight (net change, −0.22 kg [95% CI, −0.5 to 0.07]; n=1,461) or waist circumference (0.76 cm [95% CI, −0.11 to 1.63]; n=232), but significantly improved BMI (net change, −0.18 kg/m² [95% CI, −0.26 to −0.11]; P<0.001; n=1,375; no significant heterogeneity).(Xia 2020) In contrast, pooled data from 11 randomized controlled trials that assessed effects of pistachio consumption on cardiometabolic risk factors (N=506; mean of 46 patients per study) showed pistachio consumption had a statistically significant increasing effect on weight (weighted mean difference [WMD], 0.19 kg [95% CI, 0.12 to 0.26]; no heterogeneity) but a statistically insignificant effect on BMI (WMD, −0.21 kg/m² [95% CI, −0.77 to 0.34 ]) and waist circumference (WMD, 0.67 cm [95% CI, −0.27 to 1.61]). The majority of participants in these studies had MS (n=150), followed by healthy participants (n=130) and those with diabetes (n=104), dyslipidemia (n=70), or obesity (n=52).(Ghanavati 2020)

In a 4-month behavioral intervention trial in nondiabetic adults with obesity or who were overweight (N=100), participants received approximately 1.5 oz (42 g) of pistachios, making up 18% of energy intake, to be consumed daily; the pistachios were unsalted, roasted, and shelled. Consumption of a pistachio-rich diet did not significantly affect percent weight loss, BMI, or waist circumference compared with a diet devoid of nuts. The pistachio group showed a significant increase in percent energy from fat, higher intake of high-protein foods, lower intake of sweets, lower intake of added fat, and higher intake of poly- and monounsaturated fats compared with controls (P≤0.05 for each). No other differences between groups were significant (ie, blood pressure, lipid parameters, glucose, insulin).(Rock 2020)

A randomized, controlled pilot study in 60 healthy, sedentary French females (18 to 50 years of age) with a BMI between 18.5 and 25 kg/m², inclusive, evaluated the effects of pistachios on dietary profiles. Participants were not menopausal or perimenopausal. No significant differences were noted in evening energy intake, total energy intake, subjective ratings of satiety, body weight, waist and hip circumference, or body composition following consumption of 56 g of pistachios (roasted, lightly salted, in shells) as an afternoon snack for 4 weeks compared with those who consumed an isoenergetic/equiprotein savory cheese cookie. Sporadic significant differences included decreased hunger 90 minutes after the snack in the pistachio group (P=0.022) at week 1 and higher fullness after breakfast in the cookie group (P=0.048) at week 4. However, the pistachio group exhibited significantly higher micronutrient values at weeks 1 and 4 compared with the cookie group, with an average increase of 37% in thiamine, 31% in vitamin B₆, 68% in copper, and 20% in potassium.(Carughi 2019) Similar results (including significant increases in micronutrients) were found in healthy, nonobese premenopausal females following 44 g of pistachios consumed as a morning snack in a randomized, controlled noninferiority trial.(Fantino 2020)

Dosing

Quantities of pistachios consumed (often as part of a diet) and treatment durations have varied among studies. Pistachio dosages used in trials to evaluate effects on cardiometabolic risk factors, weight/dietary profile, GI health, and aging ranged from 32 to 84 g/day.(Canudas 2019, Carughi 2019, Creedon 2020, Fantino 2020, Gebauer 2008, Nowrouzi-Sohrabi 2020, Rock 2020)

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

Most adverse reactions are associated with hypersensitivity to the plant species or allergic reactions. Anaphylaxis is reported to be uncommon despite widespread use in food.(Fernandez 1995) Cross-sensitivity has occurred with other tree nuts,(Goetz 2005, Liccardi 1999, Parra 1993) the aromatic spice mahaleb from the St Lucie cherry (Prunus mahaleb; in the same genus as almonds),(Benoit 2020) and the pink peppercorn (in the same botanical family [Anacardiaceae] as cashews and pistachios).(Fong 2019)

Toxicology

Studies are lacking. One study found no cytotoxicity of plant extracts against mammalian cells.(Orhan 2006a)

Index Terms

• Pistacia lentiscus

References

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