NutriDex

The Supplement Research Compendium
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Walnut

Juglans regia

ALA-rich tree nut with solid RCT evidence for lowering LDL cholesterol

Moderate evidence 🥜Nuts🫀Heart & Metabolic⏳Longevity

✚ Updated · How we grade evidence

Evidence tier
Moderate
Research weight
Citations
10 verified / 10
Classification
Nuts
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.

Nutrition per serving 1 oz (28 g, ~14 halves)

28gSERVING
  • Sugars 0.7 g3%
  • Fibre 1.9 g7%
  • Other carbs 1.2 g4%
  • Protein 4.3 g15%
  • Fat 18.3 g65%
  • Other 1.6 g6%
What's in one serving, by weight — average composition (USDA).
Fiber7%Protein9%Vitamin E1%Magnesium11%Copper49%Manganese42%Zinc8%Selenium3%
One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
183 kcal4.3 g protein1.9 g fiber18 g fat
NutrientPer serving% daily value
Fiber1.9 g7%
Protein4.3 g9%
Vitamin E0.2 mg1%
Magnesium44 mg11%
Copper0.44 mg49%
Manganese0.96 mg42%
Zinc0.87 mg8%
Selenium1.4 µg3%
Phosphorus97 mg8%
Potassium124 mg3%
Iron0.81 mg5%
Calcium27 mg2%
Folate27 µg7%

Composition data: USDA FoodData Central ↗

What is Walnut?

Walnut (Juglans regia) is a nut or seed used for lowers ldl cholesterol, total cholesterol and triglycerides in pooled rcts (no consistent hdl change). NutriDex grades the human evidence as Moderate. Walnuts have some of the strongest human data among individual tree nuts, though the overall evidence base is best graded moderate. Meta-analyses of randomized controlled trials consistently show that adding roughly an ounce of walnuts a day modestly lowers LDL ('bad') cholesterol, total cholesterol and triglycerides, with little effect on HDL; a 2018 RCT meta-analysis (Guasch-Ferre) and a 2022 dose-response meta-analysis both confirm this, and the benefit appears independent of weight change. For hard outcomes, the landmark PREDIMED randomized trial found a Mediterranean diet supplemented with mixed nuts (half walnuts) cut major cardiovascular events versus a low-fat diet. Evidence for lower type-2 diabetes risk comes mainly from large observational cohorts (Nurses' Health Studies) rather than trials, so it is weaker. Walnuts are distinctive for being rich in the plant omega-3 ALA. Bottom line: good RCT support for cholesterol, supportive trial/cohort data for cardiovascular and metabolic benefit.

Purported Benefits

✓Lowers LDL cholesterol, total cholesterol and triglycerides in pooled RCTs (no consistent HDL change)
✓Lipid improvements occur largely independent of body weight change
✓Richest common nut source of the plant omega-3 ALA (alpha-linolenic acid)
✓Associated with lower cardiovascular event risk as part of a Mediterranean diet (PREDIMED RCT)
✓Higher intake linked to lower type-2 diabetes risk in large cohorts (observational)
✓Does not promote weight gain at typical ~1 oz/day servings despite calorie density

Dosing & Compounds

Typical Dose
1 oz (~28 g) per day, a small handful (about 14 halves)
Active Compounds
Polyunsaturated fat (PUFA), notably alpha-linolenic acid (ALA, plant omega-3)Monounsaturated fat (MUFA)Dietary fibreL-arginineVitamin E (gamma-tocopherol)MagnesiumPhytosterolsPolyphenols (ellagitannins/urolithin precursors)Copper and manganese

Safety & Cautions

Tree-nut allergy is common and can cause life-threatening anaphylaxis; walnuts are a major allergen and should be strictly avoided by allergic individuals, who may also react to other tree nuts or peanuts. Walnuts are calorie-dense (~185 kcal per 1 oz), so portion control matters for weight management. Whole or large nut pieces are a choking hazard for children under about 4 years. Those with cross-reactive pollen-food (oral allergy) syndrome may experience mild mouth itching. Educational only — always check with your doctor or pharmacist before combining Walnut with any medicine.

Key Studies ★ 10 studies

meta-analysis Eslampour 2025 ✓ Full text
GRADE-assessed dose-response meta-analysis of 49 RCTs found walnut consumption significantly reduced total cholesterol, LDL-C and triglycerides, supporting a robust lipid-lowering effect across populations.
meta-analysis Mohammadi-Sartang (endothelial) 2024 ✓ PubMed
Systematic review and meta-analysis of 6 RCTs (n=250): walnut intake significantly improved flow-mediated dilation by 0.94% (95% CI 0.12 to 1.75; p=0.02), a marker of better endothelial function.
meta-analysis Glycemic meta-analysis 2025 ✓ PubMed
Systematic review and meta-analysis of 32 RCTs: walnut supplementation significantly reduced HOMA-IR (insulin resistance) and body weight, though effects on fasting glucose and HbA1c were inconsistent.
Meta-analysis 2022 Nutrients dose-response meta-analysis ✓ PubMed
Pooled RCTs found walnut intake significantly reduced total cholesterol, LDL-C and triglycerides, with no significant change in HDL-C.
meta-analysis Neale 2020 (blood glucose) ✓ Source
Systematic review and meta-analysis of 16 RCTs found walnut consumption had no significant effect on fasting glucose, insulin or HbA1c, indicating glycemic neutrality despite the high energy density of walnuts.
Meta-analysis Guasch-Ferre et al. 2018 meta-analysis ✓ PubMed
Across 26 controlled trials, walnut-enriched diets lowered LDL cholesterol, total cholesterol and triglycerides versus control diets, with effects largely independent of body weight.
meta-analysis Aune 2016 ✓ PubMed
Dose-response meta-analysis of prospective cohorts (up to 819,448 participants, 85,870 deaths): each 28 g/day of nuts was associated with 21% lower cardiovascular disease risk (RR 0.79, 95% CI 0.70-0.88) and 22% lower all-cause mortality (RR 0.78, 95% CI 0.72-0.84).
RCT Sala-Vila 2020 (WAHA) ✓ PubMed
2-year RCT in 636 cognitively healthy elders (63-79 y) randomized to 30-60 g/day walnuts vs control: walnuts did not improve global cognition overall, but post hoc analysis suggested slower cognitive decline and less brain-network functional decline in a higher-risk (Loma Linda) subgroup.
RCT Estruch et al. (PREDIMED) 2018 ✓ PubMed
In ~7,447 high-risk adults, a Mediterranean diet supplemented with mixed nuts (50% walnuts) reduced major cardiovascular events (MI, stroke, CV death) vs a low-fat control diet over a median 4.8 years.
Cohort Pan et al. 2013 (Nurses' Health Studies) ✓ PubMed
In 137,956 women, higher walnut consumption (>=2 servings/week) was associated with about a one-third lower risk of incident type 2 diabetes after multivariable adjustment.
10 sources cited · 10 verified Search all studies on PubMed ↗

Common questions about Walnut

What is Walnut used for?

Walnut is most often taken for Lowers LDL cholesterol, total cholesterol and triglycerides in pooled RCTs (no consistent HDL change), Lipid improvements occur largely independent of body weight change, Richest common nut source of the plant omega-3 ALA (alpha-linolenic acid), Associated with lower cardiovascular event risk as part of a Mediterranean diet (PREDIMED RCT). ALA-rich tree nut with solid RCT evidence for lowering LDL cholesterol

Does Walnut work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Walnuts have some of the strongest human data among individual tree nuts, though the overall evidence base is best graded moderate. Meta-analyses of randomized controlled trials consistently show that adding roughly an ounce of walnuts a day modestly lowers LDL ('bad') cholesterol, total cholesterol and triglycerides, with little effect on HDL; a 2018 RCT meta-analysis (Guasch-Ferre) and a 2022 dose-response meta-analysis both confirm this, and the benefit appears independent of weight change. For hard outcomes, the landmark PREDIMED randomized trial found a Mediterranean diet supplemented with mixed nuts (half walnuts) cut major cardiovascular events versus a low-fat diet. Evidence for lower type-2 diabetes risk comes mainly from large observational cohorts (Nurses' Health Studies) rather than trials, so it is weaker. Walnuts are distinctive for being rich in the plant omega-3 ALA. Bottom line: good RCT support for cholesterol, supportive trial/cohort data for cardiovascular and metabolic benefit.

What is the typical dose of Walnut?

1 oz (~28 g) per day, a small handful (about 14 halves)

Is Walnut safe? Any cautions or side effects?

Tree-nut allergy is common and can cause life-threatening anaphylaxis; walnuts are a major allergen and should be strictly avoided by allergic individuals, who may also react to other tree nuts or peanuts. Walnuts are calorie-dense (~185 kcal per 1 oz), so portion control matters for weight management. Whole or large nut pieces are a choking hazard for children under about 4 years. Those with cross-reactive pollen-food (oral allergy) syndrome may experience mild mouth itching.

How many studies support Walnut?

NutriDex cites 10 sources for Walnut, graded "Moderate".

Cite this page
APA

Peh, D. (2026). Walnut (Juglans regia): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/walnut

BibTeX
@misc{nutridex_walnut,
  author       = {Peh, Daryl},
  title        = {Walnut (Juglans regia): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/walnut},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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