Know2eat

Black walnuts

Juglans nigra

What black walnuts has been studied for

2 associations assessed — 1 with at least some human evidence behind it. Strongest first.

  • 1 Limited
  • 1 Insufficient
3 things to know first — allergies, interactions and intake limits

About black walnuts

A native North American walnut with a much stronger, almost musky flavour than the English walnut and a shell hard enough to require a vice. Mostly wild-harvested rather than orchard-grown. The USDA reference entry is for dried kernels.

Also known as American black walnut, Eastern black walnut

Gut & Digestive HealthHeart Health

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how impressive the food is. How we rate evidence.

Gut microbiome

Gut & Digestive Health
Limited evidence

Has been studied in a small number of feeding trials reporting shifts in gut bacterial composition after regular walnut intake. What those shifts mean for health is not established, and most of the work used English rather than black walnuts.

Limited evidence. Early human work, or mostly lab and animal research.

1 source

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

Blood lipid profile

Heart Health
Insufficient evidence

Evidence is limited for black walnut specifically. The nut literature that reports modest LDL reductions is almost entirely on English walnuts and mixed nuts, and the few black walnut studies are small.

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 Black walnuts

Ask about Black 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
Calories619 kcal31%
Protein24.1 g48%
Total fat59.3 g76%
Carbohydrate9.58 g3%
Fibre6.8 g24%
Total sugars1.1 g—
Water4.56 g—
Fats
Saturated fat3.48 g17%
Monounsaturated fat15.4 g—
Polyunsaturated fat36.4 g—
Cholesterol0 mg0%
ALA (omega-3)2.68 g—
EPA (omega-3)0 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)33.8 g—
Vitamins
Vitamin A2 µg0%
Vitamin C1.7 mg2%
Vitamin D0 µg0%
Vitamin E2.08 mg14%
Vitamin K2.7 µg2%
Thiamin (B1)0.057 mg5%
Riboflavin (B2)0.13 mg10%
Niacin (B3)0.47 mg3%
Pantothenic acid (B5)1.66 mg33%
Vitamin B60.583 mg34%
Folate31 µg8%
Vitamin B120 µg0%
Choline32.1 mg6%
Minerals
Calcium61 mg5%
Iron3.12 mg17%
Magnesium201 mg48%
Phosphorus513 mg41%
Potassium523 mg11%
Sodium2 mg0%
Zinc3.37 mg31%
Copper1.36 mg151%
Manganese3.9 mg169%
Selenium17 µg31%
Other measured compounds
Beta-carotene24 µg—
Alpha-carotene0 µg—
Lycopene0 µg—
Lutein + zeaxanthin9 µg—
Caffeine0 mg—
Ash2.47 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, black, dried (USDA FoodData Central, FDC ID 170186).

% 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.

Nothing dependable is recorded about how preparation changes this food’s nutritional properties. Rather than guess, this section stays empty.

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

    Black walnut is a major regulated tree nut allergen, cross-reacts with English walnut and is a documented cause of anaphylaxis.

  • Worth knowing

    Black walnut hull supplements

    Black walnut hull tincture is sold as an anti-parasitic, often alongside wormwood and clove. There is no dependable human evidence behind that use, the hull contains juglone which is toxic in quantity, and the tinctures are unsuitable for anyone with a walnut allergy.

  • Worth knowing

    Mould on ground-fallen nuts

    Black walnuts are usually gathered from the ground, where damp husks encourage mould growth including aflatoxin-producing Aspergillus. Husk and dry them promptly and discard any kernel that looks or smells wrong.