Pistachio nuts: a small drop in blood pressure and no slower weight loss

Across 17 randomized trials in 940 adults, eating pistachios lowered systolic blood pressure by 2.89 mmHg (95% CI 1.67 to 4.11), with no change in waist, diastolic pressure or BMI. The same analysis reports triglycerides down by 16.76 mg/dL with a confidence interval so narrow it points to a pooling problem, so that figure is less secure than it looks. Doses and control foods varied, and many of the trials had industry support. The fear that nut fat means weight gain has been tested directly. In 100 overweight adults on a 4-month weight-loss program, adding 1.5 oz (42 g) of pistachios a day left weight loss at 4.9% against 5.1% without them. That trial and a 12-week one both ran inside weight-loss programs, so they do not show what happens when nuts are added on top of a usual diet.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Across 8 USDA samples of raw pistachios, selenium ranged from 8.6 to 111 ug per 3.5 oz (100 g) and calcium from 94 to 214 mg, while copper stayed within 1.0 to 1.1 mg. — USDA Foundation Foods, Nuts, pistachio nuts, raw (FDC 2515379), 8 samples, release 2026-04-30 (n = 8) Evidence E source
  Selenium 8.61-111 ug (median 10.31); calcium 94.3-213.5 mg (median 105.0); potassium 760-1030 mg; copper 1.0-1.11 mg; fiber 5.98-7.87 g per 3.5 oz (100 g)
• UK roasted and salted pistachio kernels carry 530 mg of sodium and 601 calories per 3.5 oz (100 g), against 45 g of fat in USDA raw kernels versus 55.4 g in the roasted UK product. — CoFID 2021 code 14-840 (Pistachio nuts, kernel only, roasted and salted) and USDA Foundation raw pistachios FDC 2515379 Evidence E source
  Roasted salted: 601 calories, fat 55.4 g, saturated 7.40 g, sodium 530 mg, fiber 7.4 g; raw USDA fat 45.02 g

What a real portion looks like

• An ounce of pistachios bought in the shell yields about 15 g of kernels, half of the 28 g in an ounce of shelled nuts. — FNDDS portions for Pistachio nuts, salted (FNDDS 42114140, FDC 2707528) Evidence E source
  1 oz in shell yields 15 g; 1 oz without shell 28 g; 1 cup without shell 128 g; 1 package 50 g
• Students given in-shell pistachios ate 125 calories on average against 211 calories for shelled ones, 41% fewer, with the same fullness. — 140 students at a mid-western US university, self-selected portions during class (n = 140) Evidence C source
  125 vs 211 calories (-86 calories, -41%, p <= .01); fullness and satisfaction not different

What your body absorbs

• In a 3-week feeding study of 16 people, pistachios delivered 22.6 kJ per gram, 5% less energy than label factors predict, because part of their fat is not absorbed. — 16 volunteers on a controlled diet with 0, 42 and 84 g/d pistachios for 3 weeks each, crossover (n = 16) Evidence B source
  Measured 22.6 kJ/g vs Atwater 23.7 kJ/g (-5%); LDL-cholesterol -6%

What cooking and storage change

• Most laboratory studies found the allergenic storage proteins of pistachio and other tree nuts stable to heating, so roasting cannot be relied on to make pistachios safe for allergic people. — 32 studies of processing and allergenicity of tree nuts, mostly in vitro (n = 32 studies) Evidence D source
  NsLTPs and seed storage proteins in pistachio and other nuts heat-stable; only PR-10 proteins in hazelnut and almond reduced by roasting

What it does to your health

• Pooling 17 trials in 940 adults, eating pistachios lowered systolic blood pressure by 2.89 mmHg and triglycerides by 16.76 mg/dL, with no change in waist or BMI. — 940 adults in 17 randomized controlled trials of pistachio intake (n = 940) Evidence A source
  SBP -2.89 mmHg (95% CI -4.11 to -1.67); TG -16.76 mg/dL (-16.89 to -16.64); FBG -3.62 mg/dL (-6.45 to -0.8); HDL +1.43 mg/dL (1.39 to 1.47)
• On a 12-week weight-loss diet, a 53 g daily pistachio snack instead of pretzels gave lower triglycerides, 88 vs 132 mg/dL, and no extra weight. — Obese adults on isocaloric weight reduction diets for 12 weeks, pistachio snack n = 31, pretzel snack n = 28 (n = 59) Evidence B source
  BMI 30.1 to 28.8 (pistachio) vs 30.9 to 30.3 (pretzel); TG at 12 weeks 88.10 vs 132.15 mg/dL (p = 0.02)
• Adding 1.5 oz (42 g) of pistachios a day to a 4-month weight-loss program did not slow weight loss: -4.9% versus -5.1% in controls. — 100 non-diabetic overweight or obese adults in a behavioral weight loss intervention, 4 months (n = 100) Evidence B source
  Weight change -4.9% (pistachio) vs -5.1% (control); systolic and diastolic BP fell in the pistachio group

Safety, limits and interactions

• In 2025 CDC traced a Salmonella Oranienburg outbreak in 4 people from 2 states to pistachio cream, one of whom was hospitalized. — 4 people in 2 US states, 2025 (n = 4) Evidence E source
  4 cases, 1 hospitalization, no deaths; outbreak declared over on August 21, 2025

What people believe that the data does not support

• The EU refused the claim that eating 1.1 oz (30 g) of nuts a day, pistachios included, helps maintain heart health, so it cannot appear on EU packs. — EU register of nutrition and health claims, snapshot 2026-09-21 Evidence E source
  Status Non-authorized; no authorized claim names pistachios

Who this works differently for

• In 48 people with type 2 diabetes, 0.88 oz (25 g) of pistachios twice a day for 12 weeks lowered HbA1c by 0.4% and fasting glucose by 16 mg/dL against control. — 48 patients with type 2 diabetes, double-blind randomized crossover, 12 weeks per phase with 8-week washout (n = 48) Evidence B source
  HbA1c -0.4%, FBG -16 mg/dl vs control (p <= 0.001); no change in HOMA-IR
• In 122 nut-allergic children tested by food challenge, 60.7% had more than one nut or sesame allergy, and cashew and pistachio allergies clustered together. — Children aged 0 to 16 years with at least one confirmed nut or sesame allergy in London, Geneva and Valencia (n = 122) Evidence C source
  Coexistent allergy 60.7% (95% CI 51.4 to 69.4%); strong cashew-pistachio correlation

What is still unknown

• A review of 21 studies found nut energy absorbed rises with processing, nut butter over roasted over raw, and asked for more trials before this changes diet advice. — 21 human and in vitro studies of almonds, cashews, hazelnuts, pistachios, walnuts and peanuts (n = 21 studies) Evidence C source
  Metabolizable energy lower than Atwater for all nuts studied; pistachios 22.6 kJ/g; ME higher for flour > chopped > whole and butter > roasted > raw

The bottom line

Part of the label energy never reaches you. In a 3-week feeding study of 16 people, pistachios delivered 22.6 kJ per gram, 5% less than the standard factors predict. A review of 21 studies across several nuts found more energy is absorbed as nuts are processed, from raw to roasted to butter, and asked for more trials before diet advice changes. In obese adults on a 12-week weight-loss diet, a 53 g salted pistachio snack in place of pretzels ended with triglycerides at 88 against 132 mg/dL. In 48 people with type 2 diabetes, 25 g twice a day for 12 weeks lowered HbA1c by 0.4% and fasting glucose by 16 mg/dL against a control meal without nuts, though a nut snack is hard to blind. Shells slow you down. An ounce bought in the shell gives about 15 g of kernels, half the 28 g in an ounce of shelled nuts. In a class of 140 students, those handed in-shell pistachios ate 125 calories against 211 calories for shelled ones and felt just as full, in a convenience sample that was not randomized. Roasted and salted kernels in the UK table carry 530 mg of sodium and 601 calories per 3.5 oz (100 g). Raw kernels vary with the orchard. Across 8 USDA samples selenium ran from 8.6 to 111 micrograms per 3.5 oz (100 g), with a typical value near 10. The EU refused the claim that 1.1 oz (30 g) of nuts a day, pistachios included, helps maintain heart health. That means the dossier did not meet the bar for a label, which is a different thing from showing no effect. Who should take care. Pistachio allergy tends to travel with cashew allergy. In 122 children with a confirmed nut or sesame allergy, 60.7% (95% CI 51.4 to 69.4) turned out to react to more than one, and cashew and pistachio clustered together. Mostly laboratory studies show pistachio allergens survive heating, so roasting should not be relied on to make them safe, and clinical tests exist only for hazelnut. In 2025 the CDC linked 4 Salmonella cases in 2 states to pistachio cream, a spread, with one person in hospital. We have no card on pistachios in pregnancy, kidney disease or with medicines, and none on aflatoxin.

Sources

1. pstn-r2-01 · food composition dataset
   Nuts, pistachio nuts, raw: Selenium, Se 23.12 UG, range 8.61-111.0 (median 10.31), 8 samples; Calcium, Ca 117.4 MG, range 94.3-213.5 (median 105.0), 8 samples; Potassium, K 947.0 MG, range 760.0-1030.0; Copper, Cu 1.054 MG, range 1.0-1.11; Fiber, total dietary 6.969 G, range 5.98-7.87
   USDA FoodData Central, Foundation Foods, FDC 2515379, release 2026-04-30 · checked 2026-09-29
2. pstn-r2-02 · food composition dataset
   Pistachio nuts, kernel only, roasted and salted (14-840): Energy 601 kcal, Fat 55.4 g, Satd FA 7.40 g, Sodium 530 mg, AOAC fibre 7.4 g; Nuts, pistachio nuts, raw (FDC 2515379): fat 45.02 g
   CoFID 2021, Public Health England, OGL v3.0, code 14-840; USDA FoodData Central FDC 2515379 · checked 2026-09-29
3. pstn-r2-03 · portion dataset
   Pistachio nuts, salted (FNDDS 42114140, fdc_id 2707528): 1 oz, in shell, yields 15 g; 1 oz, without shell 28 g; 1 cup, without shell 128 g; 1 package 50 g
   USDA FNDDS 2021-2023, FDC 2707528 · checked 2026-09-29
4. pstn-r2-10 · non-randomized human study
   A convenience sample of students at a mid-western university (n=140) was recruited, asking them to evaluate a variety of brands of pistachios. ... In condition one, subjects offered in-shell pistachios consumed an average of 125 calories. In condition two, subjects offered shelled pistachios consumed an average of 211 calories; a difference of 86 calories. Subjects in condition one consumed 41% fewer calories compared to subjects in condition two (p≤.01).
   Appetite, 2011 · checked 2026-09-29
5. pstn-r2-04 · randomized crossover feeding trial
   A crossover feeding study was conducted in which sixteen volunteers consumed pistachios for 3 weeks as part of a controlled diet. Pistachio doses were 0, 42 and 84 g/d. ... The measured energy density of pistachios was found to be 22·6 kJ/g, which is 5 % less than the currently accepted energy value of 23·7 kJ/g, as calculated using the Atwater general factors. The pistachio nut intervention lowered LDL-cholesterol by 6 %, but did not significantly change plasma total cholesterol, HDL-cholesterol or TAG.
   Br J Nutr, 2012 · checked 2026-09-29
6. pstn-r2-13 · systematic review
   The majority of the in vitro studies investigating the allergenicity of nonspecific lipid transfer proteins (nsLTPs) and seed storage proteins in hazelnut, almond, cashew nut, Brazil nut, walnut, pecan nut and pistachio nut show heat stability towards different thermal processing methods.
   Allergy, 2013 · checked 2026-09-29
7. pstn-r2-06 · meta-analysis of randomized trials
   Seventeen RCTs including 940 adults met the inclusion criteria for this systematic review and meta-analysis. Pistachio supplementation significantly reduced systolic blood pressure (BP; MD, -2.89 mmHg, 95%CI: -4.11 to -1.67; P < 0.001), triglycerides (MD, -16.76 mg/dL, 95%CI: -16.89 to -16.64; P < 0.001), fasting blood glucose (MD, -3.62 mg/dL, 95%CI: -6.45 to -0.8; P < 0.001,) and increased HDL (MD, 1.43 mg/dL, 95%CI: 1.39 to 1.47; P < 0.001) levels. However, there were not observed considerable changes in waist circumference, diastolic BP, and body mass index.
   Nutr Rev, 2022 · checked 2026-09-29
8. pstn-r2-07 · randomized controlled trial
   Each diet included an afternoon snack of either 53 g (240 cal) of salted pistachios (n = 31) or 56 g of salted pretzels (220 cal; n = 28). RESULTS: Both groups lost weight during the 12-week study (time trend, p < 0.001), but there were significant differences in the changes in body mass index between the pretzel and pistachio groups (pistachio, 30.1 ± 0.4 to 28.8 ± 0.4 vs. pretzel, 30.9 ± 0.4 to 30.3 ± 0.5). At 6 and 12 weeks, triglycerides were significantly lower in the pistachio group compared with the pretzel group (88.04 ± 9.80 mg/dL vs. 144.56 ± 18.86 mg/dL, p = 0.01 at 6 weeks and 88.10 ± 6.78 mg/dL vs. 132.15 ± 16.76 mg/dL, p = 0.02 at 12 weeks)
   J Am Coll Nutr, 2010 · checked 2026-09-29
9. pstn-r2-09 · randomized controlled trial
   This randomized controlled study enrolled non-diabetic overweight/obese adults (n = 100) assigned to a 4-month behavioral weight loss intervention only group (controls) or also prescribed 1.5 oz/day (42 g/day) of pistachios (pistachio group). ... Percent weight change was similar in the two groups (-5.1 [0.5] (mean [SE])% in the control group and -4.9 [0.6]% in the pistachio group
   Nutrients, 2020 · checked 2026-09-29
10. pstn-r2-14 · outbreak investigation
    A total of four people infected with the outbreak strain of Salmonella Oranienburg were reported from two states.
    CDC, Salmonella Outbreak Linked to Pistachio Cream, investigation update, 2025 · checked 2026-09-29
11. pstn-r2-11 · regulatory decision
    POL-HC-7666 Nuts - peanuts and tree nuts (almonds, hazelnuts, pecans, pistachios and walnuts), excluding brazil, macadamia and cashew nuts Eating 30g of nuts per day as part of a balanced diet helps maintain heart health. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7666, snapshot 2026-09-21 · checked 2026-09-29
12. pstn-r2-08 · randomized crossover trial
    In this double-blind, randomized, placebo-controlled, crossover trial, 48 diabetic patients were equally assigned to groups A and B. Patients in group A received a snack of 25 g pistachio nuts twice a day for 12 weeks and group B received a control meal without nuts. ... With respect to the total change in variables over both phases, there was a marked decrease in HbA1c (-0.4%) and fasting blood glucose (FBG) concentrations (-16 mg/dl) in the pistachio group compared with the control group (p ≤ 0.001 for both).
    Rev Diabet Stud, 2014 · checked 2026-09-29
13. pstn-r2-12 · diagnostic cohort
    Children aged 0 to 16 years with at least 1 confirmed nut or sesame seed allergy underwent sequential diagnostic food challenges to all other nuts and sesame seed. RESULTS: Overall, the rate of coexistent peanut, tree nut, and sesame seed allergy was 60.7% (n = 74/122; 95% CI, 51.4% to 69.4%). ... Strong correlations were found between cashew-pistachio, walnut-pecan, and walnut-pecan-hazelnut-macadamia clusters.
    J Allergy Clin Immunol, 2020 · checked 2026-09-29
14. pstn-r2-05 · systematic review
    Twenty-one studies were included. The ME of nuts was consistently lower than that predicted by Atwater factors for investigated nut types (almonds, cashews, hazelnuts, pistachios, walnuts, and peanuts). ... ME was influenced by nut type (ME = 22.6 kJ/g for pistachios; ME = 18.5 kJ/g for raw almonds), physical form (flour > chopped > whole nuts), heat processing (butter > roasted > raw) and dose of consumption. ... However, the strength of the evidence base was reduced by the variation in methods used between studies, suggesting that further clinical trials are needed to determine the impact of the findings of this review for clinical dietetics.
    Adv Nutr, 2023 · checked 2026-09-29