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Walnuts

Juglans regia

Also known as English walnut, Persian walnut

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The wrinkled kernel of the walnut tree, unusual among common nuts for being dominated by polyunsaturated rather than monounsaturated fat. The USDA reference entry is for the raw kernel.

CirculationHeart HealthBrain & Cognitive HealthInflammation

Potential health benefits

Best supported: Moderate

Ordered by how well the human research supports them — strongest first. A rating describes the state of the evidence, not how impressive the food is. How we rate evidence.

Endothelial function

Circulation
Moderate evidence

Several trials report improved flow-mediated dilation after walnut-enriched diets, a measure of how well blood vessels relax. The trials are short and the clinical meaning of the change is not established.

Moderate evidence. Several human studies point the same way, with real caveats.

3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Blood lipid profile

Heart Health
Insufficient evidence

Research consistently shows that walnut-enriched diets lower LDL and total cholesterol compared with control diets, across many controlled trials and several meta-analyses. Effects on HDL and triglycerides are smaller and less consistent.

What may be going on: Replacing saturated fat with the polyunsaturated fat of walnuts lowers LDL, a well-characterised effect of that fatty acid substitution.

Insufficient evidence. Not enough human research to say anything useful yet.

No source is attached to this association yet, so it is rated insufficient by default. It is listed because people commonly ask about it — not because there is evidence for it.

Cognitive ageing

Brain & Cognitive Health
Insufficient evidence

The idea that walnuts support the ageing brain is heavily marketed and poorly supported. The largest and longest trial designed to test it did not find a benefit on its primary cognitive outcome, and the observational associations are confounded by overall diet quality.

Insufficient evidence. Not enough human research to say anything useful yet.

2 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Inflammatory markers

Inflammation
Insufficient evidence

Evidence is limited and mixed. Some trials report small reductions in inflammatory markers such as C-reactive protein with walnut-enriched diets, while others find no change.

Insufficient evidence. Not enough human research to say anything useful yet.

No source is attached to this association yet, so it is rated insufficient by default. It is listed because people commonly ask about it — not because there is evidence for it.

Ask about Walnuts

Ask about Walnuts

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories654 kcal33%
Protein15.2 g30%
Total fat65.2 g84%
Carbohydrate13.7 g5%
Fibre6.7 g24%
Total sugars2.61 g—
Water4.07 g—
Fats
Saturated fat6.13 g31%
Monounsaturated fat8.93 g—
Polyunsaturated fat47.2 g—
Cholesterol0 mg0%
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)38.1 g—
Vitamins
Vitamin A1 µg0%
Vitamin C1.3 mg1%
Vitamin D0 µg0%
Vitamin E0.7 mg5%
Vitamin K2.7 µg2%
Thiamin (B1)0.341 mg28%
Riboflavin (B2)0.15 mg12%
Niacin (B3)1.13 mg7%
Pantothenic acid (B5)0.57 mg11%
Vitamin B60.537 mg32%
Folate98 µg25%
Vitamin B120 µg0%
Choline39.2 mg7%
Minerals
Calcium98 mg8%
Iron2.91 mg16%
Magnesium158 mg38%
Phosphorus346 mg28%
Potassium441 mg9%
Sodium2 mg0%
Zinc3.09 mg28%
Copper1.59 mg176%
Manganese3.41 mg148%
Selenium4.9 µg9%
Other measured compounds
Beta-carotene12 µg—
Alpha-carotene0 µg—
Lycopene0 µg—
Lutein + zeaxanthin9 µg—
Caffeine0 mg—
Ash1.78 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Nuts, walnuts, english (USDA FoodData Central, FDC ID 170187).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

  • roastedReduces ALA and polyphenols

    High-temperature or prolonged roasting oxidises part of the polyunsaturated fat, including ALA, and degrades some of the ellagitannins in the skin. Raw or lightly toasted walnuts retain more.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Allergy

    Tree nut allergy

    Walnut is a major regulated tree nut allergen and among the more common causes of severe nut reactions, including anaphylaxis. Cross-reactivity with pecan is high because the two are botanically close.

  • Worth knowing

    Rancidity

    The high polyunsaturated fat content makes walnuts oxidise faster than other nuts, producing a bitter, paint-like taste. Refrigerated or frozen storage in a sealed container is the practical answer.

  • Worth knowing

    Energy density

    Walnuts are among the most energy-dense foods eaten by the handful. Trials adding them to the diet generally find less weight gain than expected, but portion awareness still applies.