Pistachios and Antioxidants | American Pistachio Growers

Antioxidants and Other Biologically Active Compounds

Multiple studies have assessed pistachios’ antioxidant capacity and shown that pistachios contain a range of antioxidant compounds that may be beneficial to overall health from anti-inflammatory and antimicrobial activity to slowing down brain aging and preventing heart disease.

A new study conducted by Cornell University and published in the journal Nutrients found that pistachios have a high antioxidant capacity. In fact, the antioxidant capacity of pistachios rivals that of popular antioxidant-containing foods, including blueberries, pomegranates, cherries and red wine.

The high antioxidant capacity of pistachios was confirmed by a research team lead by Dr. Rui Hai Liu using two different methods of measuring antioxidants—the accepted measurement established by the United States Department of Agriculture, called ORAC, which stands for Oxygen Radical Absorbance Capacity; and CAA, short for Cellular Antioxidant Activity, which is a new method that looks more closely at what might happen with cells in the human body.

[Yuan W, Zheng B, Li T, Liu RH. Quantification of Phytochemicals, Cellular Antioxidant Activities and Antiproliferative Activities of Raw and Roasted American Pistachios (Pistacia vera L.). Nutrients. 2022; 14(15):3002. https://doi.org/10.3390/nu14153002]

Below you’ll find a handful of additional studies on pistachios and antioxidants.

For more research on the health benefits of nuts in general, visit nuthealth.org.

Açar Q, et al. Direct evaluation of the total antioxidant capacity of raw and roasted pulses, nuts and seeds. Eur Food Res Technol. 2009; 229:961–969.

In this paper, a direct procedure for the extraction-independent measurement of the total antioxidant capacity named QUENCHER was applied to raw and roasted pulses, nuts and seeds.
The results highlighted a high value of total antioxidant capacity (TAC) for some raw seed and pulses. Total antioxidant capacity values of nuts were in this order: walnut > pistachio > hazelnut > almond (with skin) >peanut > cashew nut > pinenut > coconut flour > almond(without skin). Roasting results in a substantial loss of antioxidant activity.

Alasalvar C, et al. Natural antioxidants in tree nuts. Eur J Lipid Sci Technol. 2009;111,1056–1062.

The levels of natural antioxidants and phytochemicals present in tree nuts are reported.
In general, tree nuts are not good sources of vitamins A and C. Among them, pistachio has the highest amount of vitamin A (28 mg RAE/100 g edible nut). Pistachio has the highest total isoflavones(176.9 mg/100 g), lignans (198.9 mg/100 g), and phytoestrogens (382.5 mg/100 g). Walnut contains massive amounts of antioxidant (23.07 mmol/100 g), followed by pecan (8.33 mmol/100 g), chestnut (4.67 mmol/100 g), and pistachio (1.27 mmol/100 g).

Ballistreri G, et al. Influence of ripeness and drying process on the polyphenols and tocopherols of Pistacia vera L. Molecules. 2009;14(11):4358-69.

Changes in the phenolics fraction (anthocyanins, flavonoids and stilbenes) and tocopherols of unpeeled pistachios with ripening, and the effect of the sun-drying process are investigated.
Total polyphenol levels increased with ripening, while the sun drying process caused a substantial loss.
These results suggest that unpeeled pistachios can be considered an important source of phenolics, particularly of anthocyanins. Moreover, in order to preserve these healthy characteristics, new and more efficient drying processes should be adopted.

Bisignano C, et al. In vitro antimicrobial activity of pistachio (Pistacia vera L.) polyphenols. FEMS Microbiol Lett. 2013;341(1):62-7.

Investigated antimicrobial properties of polyphenol-rich fractions derived from raw shelled and roasted salted pistachios.
Extracts from raw shelled pistachios were more active than those from roasted salted pistachios.
The bactericidal activity of pistachio extracts could be used to help control the growth of some microorganisms in foods to improve safety and may find application as a topical treatment for S. aureus.

Bolling BW, et al. Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact 1 factors. A systematic review of almonds, Brazils, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios, and walnuts. Nutr Res Rev. 2011;24(2):244-75.

Summarizes the current knowledge of the carotenoid, phenolic, and tocopherol content of tree nuts and associated studies of their antioxidant actions in vitro and in human studies.
Tree nuts are a rich source of tocopherols and total phenols and contain a wide variety of flavonoids and proanthocyanidins. In contrast, most tree nuts are not good dietary sources of carotenoids and stilbenes.
Phenolic acids are present in tree nuts but a systematic survey of the content and profile of these compounds is lacking. A limited number of human studies indicate these nut phytochemicals are bioaccessible and bioavailable and have antioxidant actions in vivo.

Bolling BW, et al. The phytochemical composition and antioxidant actions of tree nuts. Asia Pac J Clin Nutr. 2010;19(1):117-23.

While tree nut phytochemicals are bioaccessible and bioavailable in humans, the number of intervention trials conducted to date is limited.
This review summarizes tree nut: (1) phytochemicals; (2) phytochemical content included in nutrient databases and current publications; (3) phytochemicals affected by pre- and post-harvest conditions and analytical methodology; and (4) bioactivity and health benefits in humans.

Carey AN, et al. The beneficial effects of tree nuts on the aging brain. Nutr Aging. 2012;1:55-67.

Evidence is accumulating that suggests that tree nuts and their bioactive constituents have the potential to reduce oxidative stress and inflammation, as indicated by decreased lipid peroxidation in vivo and reduced production of the free radical nitric oxide and the pro-inflammatory cytokine tumor necrosis factor-alpha in vitro.
Also, tree nut consumption might have the ability to mitigate some of the cognitive decline associated with aging.
The current knowledge of how the consumption of nuts may improve brain health is reviewed, specifically focusing on walnuts, almonds, pistachios, and pecans.

Chen, Oliver et al: Photoprotection by pistachio bioactives in a 3-dimensional human skin equivalent tissue model. International Journal of Food Sciences and Nutrition, 2017. DOI:10.1080/09637486.(2017)1282437

Investigators used a 3-dimensional human skin equivalent (HSE) tissue model which closely mimics human skin and examined whether pistachios antioxidants, lutein and c-tocopheral, the predominant lipophilic antioxidants would prevent damage to the HSE when exposed to UVA radiation.
The pistachio antioxidants preserved overall skin thickness and organization, as well as fibroblast morphology, in HSE exposed to the UVA irradiation. The positive impact of lutein and c-tocopherol on UVA-induced morphological changes and the preservation of HSE by pistachio extracts implicate a potential role of pistachio consumption in promoting skin health. Additional studies are warranted to investigate the potential role of pistachio bioactives promoting skin health.

Davarynejad et al. Investigation of antioxidant capacity and some bioactive compounds of Iranian pistachio (Pistachio vera L.) cutlivars. Not Sci Biol. 2012;4(4):62-6.

This study attempts to determine the antioxidants capacity, total phenolics and amount of some major elements (nitrogen, potassium, calcium and phosphorus), present in the most important Iranian pistachio nut, to enhance the health benefits, and use in breeding programs.
11 pistachio cultivars analyzed.
Weak correlation was observed between total phenolic content and total antioxidant capacity (r2=0.3824).
The result demonstrates that there is adequate variation in major elements, antioxidants capacity and total phenolics contents within pistachio cultivars and hence there is potential for improvement towards enhancing these health-promoting photochemical in this nut.

Dreher ML. Pistachio nuts: composition and potential health benefits. Nutr Rev. 2012;70(4):234-40.

This review examines the nutrients and phytochemicals in pistachios as well as the potential health effects of these nuts.
A growing number of clinical studies suggest potential health benefits of pistachio nuts.
Five published randomized clinical studies have shown that pistachios have a beneficial effect on blood lipid profiles. Emerging clinical evidence suggests that pistachios may help reduce oxidative and inflammatory stress and promote vascular health, glycemic control, appetite management, and weight control.

Eisenhauer, B et al. Lutein and Zeaxanthin – food sources, bioavailability, and Dietary Variety in Age-Related Macular Degeneration Protection. Nutrients 2017, 9, 120; doi: 10.3390/nu9020120.(Food and Nutrition Australia)

This literature review was to examine the current evidence relating to lutein/zeaxanthin (L/Z) bioavailabilty in certain foods. L/Z are the predominant carotenoids in the retina of the eye and the impact of L/Z intake on the risk of progression of age-related macular degeneration (AMD) a leading cause of blindness in the developed world has been investigated in cohort studies and clinical trials. A variety of food sources including pistachios can provide effective levels of L/Z through diet among people at high risk of AMD or with early signs and symptoms of AMD.

Gentile C, et al. Polymeric pranthocyanidins from Sicilian pistachio (Pistacia vera L.) nut extract inhibit lipopolysaccharide-induced inflammatory response in RAW 264.7 cells. Eur J Nutr. 2012;51(3):353-63.

Studied the anti-inflammatory activity of a hydrophilic extract from Sicilian Pistacia L. (HPE) in a macrophage model and investigated bioactive components relevant to the observed effects.
Results provide molecular evidence of anti-inflammatory activity of pistachio nut and indicate polymeric proanthocyanidins as the bioactive components.

Giuffrida D, et al. Carotenoid, chlorophyll and chlorophyll-derived compounds in pistachio kernels (Pistacia vera L.) from Sicily. Ital J Food Sci. 2006;3(18):313-20.

The composition of carotenoid, chlorophyll, and chlorophyll-derived compound in Sicilian pistachio kernels (Pistacia vera L.) was investigated.
13 compounds were identified and quantified using reversed-phase liquid chromatography.
Chlorophyll a was the major component (54.14 ppm), followed by chlorophyll b (30.2 ppm).

Halvorsen BL, et al. Content of redox-active compounds (ie, antioxidants) in foods consumed in the United States. Am J Clin Nutr. 2006;84(1):95-135.

Aimed to generate a ranked food table with values for total content of redox-active compounds to test this alternative antioxidant hypothesis.
Analyzed 1113 food samples obtained from the US Department of Agriculture National Food and Nutrient Analysis Program.
Large variations in the content of antioxidants were observed in different foods and food categories. Pistachios were among the 50 foods with the highest antioxidant content.

Kay CD, et al. Pistachios increase serum antioxidants and lower serum oxidized-LDL in hypercholesterolemic adults. J Nutr. 2010;140(6):1093-8.

This study suggests that eating pistachios raises the levels of serum antioxidants, such as lutein and gamma tocopherol, which may contribute to lower levels of oxidized-LDL cholesterol.
Higher amounts of oxidized-LDL and fat-breakdown products are found in atherosclerotic plaques. These substances are thought to play a role in the development and progression of atherosclerosis, the collection of fatty materials along the arteries. Lowering oxidized-LDL decreases the risk of heart disease.

Mandalari G, et al. Bioaccessibility of pistachio polyphenols, xanthophylls, and tocopherols during simulated human digestion. Nutr. 2013;29(1):338-44.

Quantified the release of polyphenols, xanthophylls (lutein), and tocopherols from pistachios (raw pistachios, roasted salted pistachios, and muffins made with raw pistachios) during simulated human digestion.
More than 90% of the polyphenols were released in the gastric compartment, with virtually total release in the duodenal phase. No significant differences were observed between raw shelled and roasted salted pistachio.
The rapid release of the assayed bioactives in the stomach maximizes the potential for absorption in the duodenum and contributes to the beneficial relation between pistachio consumption and health-related outcomes.

Martorana M, et al. In vitro antioxidant and in vivo photoprotective effect of pistachio (Pistacia vera L., variety Bronte) seed [kernel] and skin extracts. Fitoterapia. 2013;85:41-48.

Investigated the chemical composition and antioxidant properties of two polyphenol-rich extracts from skins (TP) and decorticated seeds (SP) of Bronte pistachios, and to verify the potential use of these extracts for topical photoprotective products.
Both these extracts, and especially the TP extract, possess good radical scavenger/antioxidant properties, as shown in a series of in vitro assays carried out using homogenous and non-homogenous chemical environment.
Findings suggest that extracts from Bronte TP and SP could be successfully employed as photoprotective ingredients in topical cosmetic and pharmaceutical formulations.

Neale EP, et al. The effect of nut consumption on markers of inflammation and endothelial function: a systematic review and meta-analysis of randomized controlled trials. BMJ Open 2017

This systematic review of randomized, controlled trials (with a duration of 3 weeks or more through January 2017) examined the effect of consuming tree nuts or peanuts on inflammatory biomarkers and endothelial function. Inflammatory biomarkers included C-reactive protein (CRP), adiponectin, tumor necrosis factor alpha, interleukin-6, intercellular adhesion molecule 1, vascular cell adhesion protein 1 and flow-mediated dilation (FMD).
Nut intake resulted in significant improvements in FMD. There were small, non-significant differences in CRP and other biomarkers of inflammation. The findings suggest that more research in this area is needed, with a particular focus on randomized controlled trials.

Paola R, et al. The Antioxidant Activity of Pistachios Reduces Cardiac Tissue Injury of Acute Ischemia/Reperfusion (I/R) In Diabetic Streptozotocin (STZ)-Induced Hyperglycaemic Rats. April 2017 The FASEB Journal vol. 31 no. 1 Supplement 966.3.

This study evaluated the antioxidant properties of raw or roasted salted pistachios on reperfusion injury in diabetic rats. Reperfusion injury refers to oxidative damage to the heart that happens when blood flow is restored to the tissue after a heart attack. Because pistachios are an excellent source of antioxidants, investigators predicted that they could have a protective effect in this process.
The investigators measured markers of inflammation, oxidative damage and tissue injury in animals pre-treated with pistachios. Investigators showed that pistachios reduced tissue damage of reperfusion and lowered markers of inflammation. While the effects of raw pistachios were higher than those of roasted pistachios, results indicate that pistachios can modulate the inflammatory process associated with reperfusion

Paterniti I, et al. The anti-inflammatory and antioxidant potential of pistachios in vitro and in vivo. Nutrients. 2017 Aug 22;9(8). pii: E915. doi: 10.3390/nu9080915.

Pistachio intake has been shown to protect against oxidative stress and inflammation. This study investigated if pistachio polyphenol extracts have anti-inflammatory and antioxidant properties when tested in both a cell (in vitro) and an animal model of inflammation.
Results from the in vitro model showed that pre-treatment with pistachios polyphenol extracts protected against induced inflammation and reduced levels of inflammatory mediators. Parallel evaluation in animals also showed protection from inflammatory damage as well as antioxidant activity.

Pérez-Jiménez J, et al. Identification of the 100 richest dietary sources of polyphenols: an application of the Phenol-Explorer database. Eur J Clin Nutr. 2010;64:S112-20.

Contents of individual polyphenols have been determined by chromatography. These data, scattered in several hundred publications, have been compiled in the Phenol-Explorer database.
The aim of this paper is to identify the 100 richest dietary sources of polyphenols using this database.
Pistachio made the list oft he 100 richest dietary sources of polyphenols.

Rajaei A, et al. Antioxidant, anti-microbial and antimutagenicity activities of pistachio (Pistachia vera) green hull extract. Food Chem Toxicol. 2010;48(1):107-12.

Antioxidant, anti-microbial and antimutagenicity activities of pistachio (Ahmadaghaei variety) green hull extracts (crude and purified extracts) were studied.
The results of antimutagenicity test showed that phenolic compounds of pistachio green hull have antimutagenicity activity against direct mutagen of 2-nitrofluorene.
The results obtained indicate that pistachio green hull may become important as a cheap and noticeable source of compounds with health protective potential and anti-microbial activity.

Sari I, et al. Effect of pistachio diet on lipid parameters, endothelial function, inflammation, and oxidative status: a prospective study. Nutrition. 2010;26(4):399-404.

Aimed to investigate effect of the Antep pistachio (Pistacia vera L.) on blood glucose, lipid parameters, endothelial function, inflammation, and oxidation in healthy young men living in a controlled environment.
A Mediterranean diet was administered to normolipidemic 32 healthy young men for 4 weeks.
Demonstrated that a pistachio diet improved blood glucose levels, endothelial function, and some indices of inflammation and oxidative status in healthy young men.
These findings are in accordance with the idea that nuts, in particular pistachio nuts, have favorable effects beyond lipid lowering that deserve to be evaluated with prospective follow-up studies.

Seeram NP, et al. Pistachio skin phenolics are destroyed by bleaching resulting in reduced antioxidative capacities. J Agric Food Chem. 2006;54:7036-40.

Raw nuts preserved phenolic levels and antioxidant capacity better than roasted nuts, suggesting contributing effects of other substances and/or matrix effects that are destroyed by the roasting process.
The destruction of bioactive phenolics in pistachio skins may negatively impact the potential health benefits arising from pistachio consumption.

Tomaino A, et al. Antioxidant activity and phenolic profile of pistachio (Pistacia vera L., variety Bronte) seeds and skins. Biochimie. 2010;92(9):1115-22.

The antioxidant activity of pistachio seeds [kernels] and skins were determined by means of four different assays.
Pistachio skins have shown to possess a better activity with respect to seeds [kernels] in all tests.
The excellent antioxidant activity of pistachio skins can be explained by its higher content of antioxidant phenolic compounds.