Pine nuts and walnuts: only one of them has been tested

Across 26 controlled trials with 1059 people, walnut-enriched diets lowered LDL cholesterol by 5.5 mg/dL more than control diets (95% CI 3.3 to 7.7), about 3.7 percent. A second pool of 25 randomized trials with 2155 people found walnuts lowered apolipoprotein B by 0.06 g/L and left blood pressure unchanged. Pine nuts have no such evidence. We found no outcome trial of whole pine nuts and no study comparing the two. On the label they look alike. Across 8 USDA samples each, pine nuts carry 1.12 mg of copper per 3.5 oz (100 g) and walnuts 1.21 mg, and walnuts carry more fiber, 5.2 g against 3.9 g. Raw English walnuts hold 49.3 g of polyunsaturated fat per 3.5 oz (100 g), against 6.1 g of saturated fat.

How much is actually in it

• Across 8 USDA samples, raw English walnuts carried 49.3 g of polyunsaturated fat per 3.5 oz (100 g), ranging from 45.6 to 51.5 g, against 6.1 g of saturated fat. — USDA Foundation Foods samples of Nuts, walnuts, English, halves, raw (n = 8 samples) Evidence E source
  PUFA 49.331 g per 3.5 oz (100 g) (range 45.55 to 51.49); SFA 6.054 g (5.81 to 6.47); MUFA 9.625 g (8.95 to 10.48)
• Per 100 g, pine nuts and walnuts carry similar copper (1.12 mg against 1.21 mg), while walnuts have more fiber (5.2 g against 3.9 g), each across 8 USDA samples. — USDA Foundation Foods samples of Nuts, pine nuts, raw and Nuts, walnuts, English, halves, raw (n = 8 samples) Evidence E source
  Copper 1.119 mg pine nuts (1.07 to 1.16) vs 1.206 mg walnuts (1.02 to 1.39); fiber 3.941 g (3.32 to 4.58) vs 5.21 g (4.3 to 7.38)

What your body absorbs

• In a 3-week controlled feeding crossover in 18 adults, a 0.99 oz (28 g) serving of walnuts delivered 146 calories, 21 percent less than the 185 calories predicted by the Atwater factors. — 18 healthy adults, mean age 53, BMI 28.8, fully controlled diet with or without 42 g walnuts a day for 3 weeks each (n = 18) Evidence B source
  Metabolizable energy 5.22 calories/g vs 6.61 calories/g predicted; 39 calories less per 28 g serving (P < 0.0001)

What cooking and storage change

• A review of 32 studies found that roasting may lower the allergenicity of some nut proteins, but the lipid transfer and storage proteins of walnut largely withstand heat. — clinical and laboratory studies of processed tree nuts (n = 32 articles) Evidence D source
  Heat stability of nsLTPs and seed storage proteins in walnut and other nuts; PR-10 reduction in hazelnut and almond

What it does to your health

• Across 25 randomized trials with 2155 people, walnuts lowered apolipoprotein B by 0.06 g/L but did not change blood pressure. — adults in 25 RCTs (26 arms) of walnut supplementation published 1997 to 2020 (n = 2155) Evidence A source
  ApoB WMD -0.06 (95% CI -0.10 to -0.01); systolic BP -1.20 mmHg (95% CI -4.02 to 1.61, not significant); ApoA1 unchanged
• Across 26 controlled trials with 1059 people, walnut-enriched diets lowered LDL cholesterol by 5.5 mg/dL more than control diets, without changing body weight. — adults in 26 clinical trials comparing walnut-enriched and control diets, to January 2018 (n = 1059) Evidence B source
  LDL cholesterol WMD -5.51 mg/dL (95% CI -7.72 to -3.29), 3.73% greater reduction; weight WMD -0.26 lb (95% CI -4.7 to 4.1; metric: -0.12 kg, -2.12 to 1.88)

Safety, limits and interactions

• Pine mouth syndrome is a bitter or metallic taste disturbance starting 1 to 3 days after eating affected pine nuts, linked to Pinus armandii, and the only described treatment is to stop eating the nuts. — several thousand reported cases, clinical description and case definition Evidence D source
  Taste disturbance onset 1 to 3 days after ingestion; toxin not isolated
• The FDA-approved levothyroxine label warns that walnuts, soybean flour, cottonseed meal and dietary fiber may bind the drug and reduce its absorption. — people taking levothyroxine sodium Evidence E source
  Possible reduced levothyroxine absorption; no size stated

What people believe that the data does not support

• The European Union refused the broad claim that walnuts support cardiovascular health, while pine nuts have no claim in the register at all. — European Union food labeling, walnut and pine nut claims Evidence E source
  POL-HC-8134 non-authorized; one narrower walnut claim on vascular elasticity (POL-HC-6525) authorized

Who this works differently for

• Across 36 prevalence studies, walnut was among the most commonly reported tree nut allergies in the USA and the UK, while hazelnut led in Europe. — children and adults in 36 prevalence studies, 1996 to 2014, mostly Europe, UK and USA (n = 36 studies) Evidence C source
  Challenge-confirmed prevalence under 2%; probable 0.05 to 4.9%; with oral allergy syndrome 8 to 11.4%
• In adults with prediabetes, 2 oz (56 g) of walnuts a day for 6 months did not change fasting glucose or HbA1c. — adults with prediabetes or at risk of diabetes in 5 RCTs, 371 participants in total (n = 371) Evidence B source
  Walnuts 56 g/day for 6 months: no effect on fasting glucose or HbA1c

What is still unknown

• Pooling trials of tree nuts and peanuts, eating nuts did not measurably raise resting energy expenditure (28.6 calories a day, 95% CI -10.7 to 67.8). — adults in RCTs and feeding studies of tree nuts and peanuts, to June 2021 (n = 1121 across 27 studies) Evidence A source
  Resting energy expenditure WMD 28.6 calories/d (95% CI -10.7 to 67.8), not significant

The bottom line

The label overstates walnut calories. In a 3-week controlled feeding crossover in 18 adults, a 0.99 oz (28 g) serving delivered 146 calories, 39 calories less than the 185 calories the standard Atwater factors predict. No such measurement exists for pine nuts. Pooling 27 studies of tree nuts and peanuts, nut eating did not measurably raise resting energy expenditure (28.6 calories a day, 95% CI -10.7 to 67.8), so burning more energy does not explain why nuts fit into diets. In adults with prediabetes, one trial of 2 oz (56 g) of walnuts a day for 6 months did not change fasting glucose or HbA1c. The EU refused the broad claim that walnuts support cardiovascular health, while one narrower walnut claim on blood vessel elasticity is authorized, and pine nuts have no claim in the register. The cautions are specific. Walnut is among the most common tree nut allergies in the USA and the UK. We have no card on pine nut allergy, and the prevalence review did not single it out. Laboratory work shows the lipid transfer and storage proteins of walnut largely withstand roasting, so roasted walnuts should not be assumed safe for someone allergic to them. The approved levothyroxine label warns that walnuts, along with soybean flour and dietary fiber, may bind the drug and reduce its absorption, with no size given, and timing belongs with the prescriber. Pine nuts can cause pine mouth, a bitter or metallic taste disturbance that starts 1 to 3 days after eating affected nuts, described in case series with the toxin never isolated.

Sources

1. pnwn-r4-01 · USDA FoodData Central Foundation Foods, dataset
   Nuts, walnuts, English, halves, raw (USDA Foundation Foods, release 2026-04-30): Fatty acids, total polyunsaturated 49.331 g, range 45.55-51.49 (median 50.31), samples 8; Fatty acids, total saturated 6.054 g, range 5.81-6.47, samples 8; Fatty acids, total monounsaturated 9.625 g, range 8.95-10.48, samples 8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-29
2. pnwn-r4-02 · USDA FoodData Central Foundation Foods, dataset
   Nuts, pine nuts, raw: Copper, Cu 1.119 mg, range 1.07-1.16, samples 8; Fiber, total dietary 3.941 g, range 3.32-4.58, samples 8. Nuts, walnuts, English, halves, raw: Copper, Cu 1.206 mg, range 1.02-1.39, samples 8; Fiber, total dietary 5.21 g, range 4.3-7.38, samples 8 (USDA Foundation Foods, release 2026-04-30)
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-29
3. pnwn-r4-03 · randomized crossover trial
   One 28-g serving of walnuts contained 146 kcal (5.22 kcal/g), 39 kcal/serving less than the calculated value of 185 kcal/serving (6.61 kcal/g).
   J Nutr, 2016 · checked 2026-09-29
4. pnwn-r4-08 · 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
5. pnwn-r4-04 · meta-analysis of RCTs
   Walnut significantly decreased ApoB (WMD = -0.06; 95% CI: -0.10, -0.01, p = 0.002), but did not affect ApoA1 (WMD = -0.50; 95% CI: -1.34, 0.33, p = 0.249), systolic blood pressure (SBP) (WMD = -1.20; 95% CI: -4.02, 1.61, p = 0.401) and diastolic blood pressure (DBP) (WMD = -0.44; 95% CI: -2.55, 1.67, p = 0.682).
   Endocrinol Diabetes Metab, 2026 · checked 2026-09-29
6. pnwn-r4-05 · meta-analysis of controlled trials
   The following weighted mean differences (WMDs) in reductions were obtained for walnut-enriched diets compared with control groups: -6.99 mg/dL (95% CI: -9.39, -4.58 mg/dL; P < 0.001) (3.25% greater reduction) for total blood cholesterol (TC) and -5.51 mg/dL (95% CI: -7.72, -3.29 mg/dL; P < 0.001) (3.73% greater reduction) for low-density lipoprotein (LDL) cholesterol.
   Am J Clin Nutr, 2018 · checked 2026-09-29
7. pnwn-r4-09 · case series
   A clinically compatible case of PMS must include taste disturbance, usually characterized as bitter or metallic, following the ingestion of affected pine nuts by 1 to 3 days.
   Semin Neurol, 2012 · checked 2026-09-29
8. pnwn-r4-11 · FDA drug label section
   Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of levothyroxine sodium from the gastrointestinal tract.
   Levothyroxine Sodium, FDA-approved label, effective 2026-03-24 · checked 2026-09-29
9. pnwn-r4-12 · regulatory register entry
   POL-HC-8134 Walnuts Walnuts support cardiovascular health. Non-authorised
   EU Register on nutrition and health claims, claim POL-HC-8134, snapshot 2026-09-21 · checked 2026-09-29
10. pnwn-r4-07 · systematic review
    Prevalence of individual tree nut allergies varied significantly by region with hazelnut the most common tree nut allergy in Europe, walnut and cashew in the USA and Brazil nut, almond and walnut most commonly reported in the UK.
    Curr Allergy Asthma Rep, 2015 · checked 2026-09-29
11. pnwn-r4-10 · systematic review of RCTs
    Consumption of 56 g/d walnuts for 6 months was not found to affect FPG or HbA1c concentrations.
    Br J Nutr, 2019 · checked 2026-09-29
12. pnwn-r4-06 · meta-analysis of RCTs
    The meta-analyses identified a nonsignificant increase in REE associated with nut consumption (weighted mean difference: 28.6 kcal/d; 95% CI: -10.7, 67.8 kcal/d).
    Adv Nutr, 2023 · checked 2026-09-29