Pecans and walnuts: both lower LDL a little

Pooling 49 randomized trials with 4611 adults, walnuts lowered LDL cholesterol by 5.7 mg/dL (95% CI 3.5 to 7.9), in a 2026 analysis we could read only as an abstract. Pooling 10 short, small randomized trials run mostly in the US and Brazil, pecans lowered LDL by 7.4 mg/dL (95% CI 4.0 to 10.8). Those two numbers come from different pools of trials, so they cannot rank one nut above the other, and the walnut evidence is about five times larger. One trial looked at dose. In 102 adults with a BMI of 28 or more or abnormal blood lipids, pecans at 13% or 20% of daily calories cut LDL by about 12 mg/dL, while 6% changed nothing, and the abstract does not say how long it ran. Across 25 randomized trials with 2155 people, walnuts lowered apolipoprotein B slightly, and the change in systolic blood pressure (minus 1.2 mmHg, 95% CI minus 4.0 to plus 1.6) did not reach significance.

How much is actually in it

• Per 100 g, raw pecans carry about 39 g of monounsaturated fat against 9.6 g in walnuts, while walnuts carry about 49 g of polyunsaturated fat against 23 g in pecans. — USDA Foundation Foods samples of Nuts, pecans, halves, raw and Nuts, walnuts, English, halves, raw (n = 8 samples each) Evidence E source
  MUFA 39.282 g pecans (31.52 to 46.35) vs 9.625 g walnuts (8.95 to 10.48); PUFA 22.924 g (16.09 to 28.13) vs 49.331 g (45.55 to 51.49); total fat 73.28 g (9 samples) vs 69.74 g
• Walnuts have about half again as much protein as pecans per 3.5 oz (100 g) (14.6 g against 10.0 g in USDA samples), and British tables give the same gap (14.7 g against 9.2 g). — USDA Foundation Foods raw pecans and English walnuts, CoFID 2021 codes 14-837 and 14-879 (n = USDA samples plus one CoFID value each) Evidence E source
  Protein USDA 9.96 g pecans (8.75 to 11.29) vs 14.56 g walnuts (12.93 to 16.32); CoFID 9.2 g vs 14.7 g; energy CoFID 689 vs 688 calories per 3.5 oz (100 g)

What a real portion looks like

• A 1 oz (28 g) serving gives about 213 calories for unroasted pecans and 207 calories for walnuts, and a cup weighs 3.5 oz (100 g) for pecans but 120 g for walnuts. — FNDDS foods Pecans, unroasted (42112100) and Walnuts, excluding honey roasted (42116000) (n = survey portion weights) Evidence E source
  Pecans 750 calories per 3.5 oz (100 g), 212.6 calories per oz; walnuts 730 calories per 3.5 oz (100 g), 207.0 calories per oz; 1 cup 100 g vs 120 g; 1 nut 2 g each
• In an RCT on 102 adults with excess weight or dyslipidemia, pecans at 13% or 20% of daily energy cut LDL cholesterol by about 12 mg/dL, while 6% did nothing. — Adults with BMI 28 or higher or dyslipidemia, randomized to 6%, 13% or 20% of energy from pecans or nut-free control (n = 102) Evidence B source
  LDL-C -12.7 mg/dL (13% group) and -11.9 mg/dL (20% group), P < 0.05; no change at 6% or control

What your body absorbs

• In a controlled feeding trial on 18 adults, a 0.99 oz (28 g) serving of walnuts delivered 146 calories, 21% less than the 185 calories predicted by standard Atwater factors. — Healthy adults, mean age 53.1 y, BMI 28.8, randomized crossover, two 3-week periods with 42 g walnuts per day (n = 18) Evidence B source
  Metabolizable energy 5.22 calories/g vs 6.61 calories/g predicted, 21% lower (P < 0.0001)
• In a crossover trial on 16 adults, a pecan meal doubled plasma gamma-tocopherol at 8 hours and cut oxidized LDL by 26 to 33% over 2 to 8 hours. — Healthy men and women aged 23 to 44, BMI 22.7, single test meals with 1-week washout (n = 16) Evidence B source
  Plasma gamma-tocopherol doubled at 8 h (P < 0.001); oxidized LDL down 30, 33 and 26% at 2, 3 and 8 h (P < 0.05)

What cooking and storage change

• By USDA retention factors for roasted nuts and seeds, roasting keeps all the minerals but loses about 15% of thiamin and 20% of folate. — USDA Nut and Seed Products group (code 12), method NUTS,ROASTED; group factor, not measured on pecans or walnuts by name (n = group factor) Evidence E source
  Retained: thiamin 85%, folate 80%, vitamin C 80%, phosphorus 80%, riboflavin, niacin, B6 95%, calcium, iron, magnesium, potassium, zinc, copper 100%

What it does to your health

• Pooling 49 randomized trials with 4611 adults, walnut intake lowered LDL cholesterol by 5.7 mg/dL and total cholesterol by 6.4 mg/dL. — Adults in 49 randomized controlled trials (57 effect sizes) (n = 4611) Evidence A source
  LDL-C -5.68 mg/dL (95% CI -7.89 to -3.47), TC -6.39 mg/dL (95% CI -8.54 to -4.23), TG -6.24 mg/dL (95% CI -9.49 to -2.99), HDL-C and ApoB not significant overall
• Pooling 10 randomized trials, pecan intake lowered LDL cholesterol by 7.4 mg/dL and total cholesterol by 8.5 mg/dL, with no change in HDL cholesterol. — Adults across 10 randomized controlled trials, 4 to 12 weeks (n = 10 RCTs) Evidence A source
  LDL-C -7.42 mg/dL (95% CI -10.83 to -4.01), TC -8.49 mg/dL (95% CI -12.61 to -4.37), TG -14.06 mg/dL (95% CI -22.37 to -5.75)
• Across 25 randomized trials with 2155 patients, walnuts lowered apolipoprotein B slightly but did not change blood pressure. — Adults in 25 RCTs (26 arms), published 1997 to 2020 (n = 2155) Evidence A source
  ApoB WMD -0.06 (95% CI -0.10 to -0.01); SBP -1.20 mmHg (95% CI -4.02 to 1.61) and DBP -0.44 (95% CI -2.55 to 1.67), not significant
• An umbrella review of meta-analyses of randomized trials rated walnuts, with moderate evidence, as causing small to moderate LDL cholesterol reductions. — Adults in RCTs pooled by 108 systematic reviews and 37 guidelines (n = 108 systematic reviews) Evidence A source
  Small to moderate LDL reduction, moderate certainty (GRADE)

Safety, limits and interactions

• Walnut is among the most common tree nut allergies in the USA and UK, and challenge-confirmed tree nut allergy affects under 2% of people. — 36 population prevalence studies, mostly children, Europe, UK and USA (n = 36 studies) Evidence C source
  Challenge-confirmed prevalence < 2%; probable 0.05 to 4.9%
• The FDA-approved levothyroxine label names walnuts among foods that may bind the drug and reduce its absorption. — People taking levothyroxine sodium Evidence E source
  May decrease absorption (no size given)

What people believe that the data does not support

• The EU rejected the claim that eating 1.1 oz (30 g) of nuts a day, pecans and walnuts included, helps maintain heart health. — EU register, nut group claim covering peanuts, almonds, hazelnuts, pecans, pistachios and walnuts Evidence E source
  Non-authorized
• The EU rejected the label claim that walnuts support cardiovascular health, while allowing a narrower claim on blood vessel elasticity. — EU register, walnut claims Evidence E source
  Non-authorized (POL-HC-8134); Authorised (POL-HC-6525)

Who this works differently for

• In people who already have atherosclerotic heart disease, nuts including pecans at a median 30 g a day for 6 to 12 weeks did not change blood pressure. — Patients with atherosclerotic cardiovascular disease in 5 RCTs, nuts almonds, pecans, Brazil nuts and mixed nuts (n = 436) Evidence A source
  SBP MD -1.16 mmHg (95% CI -5.68 to 3.35), DBP MD 0.10 mmHg (95% CI -2.30 to 2.51)
• In adults with prediabetes, 2 oz (56 g) of walnuts a day for 6 months did not change fasting glucose or HbA1c, in the one walnut trial of a 5-RCT systematic review. — Adults with prediabetes or at risk of diabetes in 5 RCTs (n = 1 walnut RCT (371 across the 5 RCTs)) Evidence B source
  No effect of walnuts on FPG or HbA1c

What is still unknown

• A systematic review of 21 human and lab studies found nuts give less energy than labels predict, more so when raw and whole than roasted or as butter, but pecans were never measured. — Human feeding studies in adults and in vitro digestion studies of almonds, cashews, hazelnuts, pistachios, walnuts and peanuts (n = 21 studies) Evidence C source
  ME consistently below Atwater prediction; energy release flour > chopped > whole, butter > roasted > raw

The bottom line

The fat inside them differs. Per 100 g raw, pecans carry about 39 g of monounsaturated fat and 23 g of polyunsaturated, by USDA averages of 8 samples each, and the pecan split varies widely from sample to sample. Walnuts carry about 9.6 g and 49 g. Walnuts also have more protein, 14.6 g against 10.0 g per 3.5 oz (100 g) in USDA samples, and British tables show the same gap. A 28 g handful comes to about 213 calories of pecans or 207 calories of walnuts in US survey data, computed from 100 g values. For walnuts that label figure runs high: in a feeding trial of 18 adults, a 0.99 oz (28 g) serving delivered 146 calories, 21% less than predicted, in a small single-center study partly funded by industry. Pecans have never been measured this way, so we do not know if the same gap applies. Roasting, by USDA group factors for nuts from a 1975 table, keeps all the minerals and about 85% of thiamin. After a single pecan meal, 16 young adults had twice the plasma gamma-tocopherol at 8 hours and 26 to 33% less oxidized LDL over 2 to 8 hours. Those are short-term blood markers, not a health outcome. In adults with prediabetes, 2 oz (56 g) of walnuts a day for 6 months did not change fasting glucose or HbA1c, in the one walnut trial inside a 5-trial review. In people who already had atherosclerotic heart disease, mixed nuts including pecans at a median 30 g a day for 6 to 12 weeks did not change blood pressure across 5 trials. The EU register rejected the claim that 1.1 oz (30 g) of nuts a day helps maintain heart health, for a nut group that includes both, and separately rejected the claim that walnuts support cardiovascular health. The register snapshot does not give the reasons. Walnut is among the most common tree nut allergies in the US and UK. Across 36 prevalence studies, mostly in children, allergy to tree nuts confirmed by food challenge affected under 2% of people, and pecan was not counted separately. If you take levothyroxine, its FDA label names walnuts among foods that may bind the drug and lower its absorption, with no size given, and pecans are not named. We have no card on pregnancy or young children for either nut.

Sources

1. pcwn-r5-01 · USDA FoodData Central Foundation Foods, dataset
   Nuts, pecans, halves, raw: Fatty acids, total monounsaturated 39.282 g, range 31.52-46.35, samples 8; Fatty acids, total polyunsaturated 22.924 g, range 16.09-28.13, samples 8; Total lipid (fat) 73.28 g, range 69.81-75.93, samples 9. Nuts, walnuts, English, halves, raw: Fatty acids, total monounsaturated 9.625 g, range 8.95-10.48, samples 8; Fatty acids, total polyunsaturated 49.331 g, range 45.55-51.49, samples 8; Total lipid (fat) 69.74 g, range 67.49-71.43, samples 8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
2. pcwn-r5-02 · USDA Foundation Foods and CoFID 2021, datasets
   USDA Nuts, pecans, halves, raw: Protein 9.9587 g, range 8.745-11.289; Nuts, walnuts, English, halves, raw: Protein 14.5644 g, range 12.932-16.324. CoFID 2021 14-837 Pecan nuts, kernel only: Protein 9.2 g, Energy 689 kcal, Fat 70.1 g; 14-879 Walnuts, kernel only: Protein 14.7 g, Energy 688 kcal, Fat 68.5 g
   USDA FoodData Central Foundation Foods 2026-04-30; CoFID 2021 (Public Health England, OGL v3.0) · checked 2026-10-02
3. pcwn-r5-03 · USDA FNDDS, dataset
   Pecans, unroasted (fdc 2707522): Energy 750 KCAL per 100 g; 1 oz 28 g 212.6 KCAL; 1 cup 100 g. Walnuts, excluding honey roasted (fdc 2707531): Energy 730 KCAL per 100 g; 1 oz 28 g 207.0 KCAL; 1 cup 120 g
   USDA Food and Nutrient Database for Dietary Studies (FNDDS), as loaded in FoodData Central 2026 · checked 2026-10-02
4. pcwn-r5-11 · randomized controlled dose-response trial
   Change in total cholesterol (TC), low-density lipoprotein cholesterol, apolipoprotein B, non-HDL cholesterol, and TC/HDL cholesterol ratio all decreased from preintervention to postintervention in the middle (MID) (-13.3 ± 3.4, -12.7 ± 3.3, -9.2 ± 2.3, -13.9 ± 3.2, and -0.3 ± 0.1 mg/dL, respectively; P < 0.05 for all) and HIGH (-12.7 ± 3.6, -11.9 ± 3.4, -7.8 ± 1.9, -13.8 ± 3.6, and -0.3 ± 0.1 mg/dL, respectively; P < 0.05 for all) groups compared with no change in the LOW or CON groups.
   J Nutr, 2026 · checked 2026-10-02
5. pcwn-r5-04 · randomized crossover feeding 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). The ME of the walnuts was 21% less than that predicted by the Atwater factors (P < 0.0001).
   J Nutr, 2016 · checked 2026-10-02
6. pcwn-r5-05 · randomized crossover postprandial trial
   Following the whole and blended pecan test meals, plasma concentrations of γ-tocopherols doubled at 8 h (P < 0.001) and hydrophilic- and lipophilic-ORAC increased 12 and 10% at 2 h, respectively. Post whole pecan consumption, oxidized LDL decreased 30, 33, and 26% at 2, 3, and 8 h, respectively (P < 0.05)
   J Nutr, 2011 · checked 2026-10-02
7. pcwn-r5-07 · USDA Table of Nutrient Retention Factors Release 6, dataset
   USDA-RETN-R6:2203 NUTS,ROASTED (Nut and Seed Products): thiamin_mg 85%; folate_total_ug 80%; vitamin_c_mg 80%; phosphorus_mg 80%; riboflavin_mg 95%; niacin_mg 95%; vitamin_b6_mg 95%; calcium_mg, iron_mg, magnesium_mg, potassium_mg, zinc_mg, copper_mg 100%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), Retn_Code 2203 · checked 2026-10-02
8. pcwn-r5-08 · systematic review and dose-response meta-analysis of RCTs
   The pooled analysis of 49 RCTs (57 effect sizes; 4611 participants) showed that Walnut consumption significantly reduced and TG (WMD: -6.24 mg/dL, 95% CI: [-9.49, -2.99], p < 0.001), TC (WMD: -6.39 mg/dL, 95% CI: [-8.54, -4.23], p < 0.001), and LDL-C (WMD: -5.68 mg/dL; 95% CI: [-7,89, -3.47], p < 0.001)
   Food Sci Nutr, 2026 · checked 2026-10-02
9. pcwn-r5-09 · systematic review and meta-analysis of randomized controlled trials
   significant reductions were observed in TC (WMD: − 8.49 mg/dL; 95% CI: − 12.61 to − 4.37; P < 0.001; I²=0.0%), TG (WMD: − 14.06 mg/dL; 95% CI: − 22.37 to − 5.75; P = 0.001; I²=0.0%), and LDL-C levels (WMD: − 7.42 mg/dL; 95% CI: − 10.83 to − 4.01; P < 0.001; I²=0.0%) following pecan consumption
   Diabetol Metab Syndr, 2026 · checked 2026-10-02
10. pcwn-r5-10 · systematic review and 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 2026-10-02
11. pcwn-r5-12 · umbrella review of RCT meta-analyses
    With moderate evidence, avocados and turmeric caused moderate to large reductions. Pulses, hazelnuts, walnuts, high-fiber/wholegrain foods, and green tea caused small to moderate reductions, whereas sugar caused a small increase.
    Nutr Metab Cardiovasc Dis, 2021 · checked 2026-10-02
12. pcwn-r5-15 · systematic review of observational prevalence studies
    Challenge-confirmed IgE-mediated tree nut allergy prevalence was less than 2 % (although only seven studies used this gold standard) while probable tree nut allergy prevalence ranged from 0.05 to 4.9 %. ... 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 2026-10-02
13. pcwn-r5-16 · FDA-approved drug label
    Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of levothyroxine sodium from the gastrointestinal tract.
    DailyMed, levothyroxine sodium label f059a576-bb4b-441d-917e-4338bc3df403, effective 2026-03-24 · checked 2026-10-02
14. pcwn-r5-17 · EU health claim register entry
    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 2026-10-02
15. pcwn-r5-18 · EU health claim 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 2026-10-02
16. pcwn-r5-13 · systematic review and meta-analysis of RCTs
    The nuts evaluated were almonds, pecans, Brazil nuts, and mixed nuts, with portions that varied between 5 g and 85 g (median: 30 g/day). The intervention period varied between 6 and 12 weeks. The nuts had no effect on fasting glucose and anthropometric indices, although the certainty of the evidence for most of these outcomes was low or very low. They also had no effect on systolic (mean difference [MD]: -1.16 mmHg [95% CI, -5.68 to 3.35], I2 = 0%-moderate certainty of evidence) or diastolic (MD: 0.10 mmHg [95% CI, -2.30 to 2.51], I2 = 0%-high certainty of evidence) blood pressure.
    Nutr Rev, 2025 · checked 2026-10-02
17. pcwn-r5-14 · 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 2026-10-02
18. pcwn-r5-06 · systematic review, narrative synthesis
    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.
    Adv Nutr, 2023 · checked 2026-10-02