Black Walnuts: Nutrients, What Research Shows and Safety
Black walnuts as a food: USDA nutrients, how they compare with English walnuts, tree nut allergy and walnut cross-reactivity, and what research has and has not tested.
Content last updated . This page has not been medically reviewed.
Black walnuts are the kernels of Juglans nigra, a tree in the walnut genus (Juglans) that grows in North America. They are a tree nut: the part eaten is the kernel inside a very hard shell. People eat them for their fats, protein and minerals. This page covers black walnuts as a food, keeps them apart from hull, bark or leaf products and from hype, and says plainly that almost all the nut research we found is about English walnuts, not black walnuts.
Read this first
- Black walnuts are a tree nut. Tree nut allergy can be life-threatening and is outgrown in fewer than 10% of cases. [2] For trouble breathing or swelling of the lips, mouth or throat, call 911 (or your local emergency number). [3][4]
- Walnut and pecan are described as highly cross-reactive. [2] We did not find a study of black walnut allergens, so people with a tree nut allergy should ask an allergist before trying black walnuts. This caution is ours, based on the shared walnut group; it is not a finding from a black walnut study.
- Whole or chopped nuts and thick nut spreads are choking hazards for young children (CDC). [6]
- Black walnuts are energy dense: about 175 kcal in one ounce (28 g). [1]
- Evidence in short: pooled trials of English walnuts and of tree nuts overall found lower LDL cholesterol. We found no trials of black walnuts as food. [7][9]
What is in it (USDA values)
| Nutrient | Per 100 g | Per 1 ounce (28.35 g, USDA portion) | % Daily Value per serving |
|---|---|---|---|
| Energy | 619 kcal | 175 kcal | no DV |
| Total fat | 59.33 g | 16.8 g | 22% |
| Saturated fat | 3.48 g | 0.99 g | 5% |
| Protein | 24.06 g | 6.8 g | 14% |
| Fiber | 6.8 g | 1.9 g | 7% |
| Alpha-linolenic acid (ALA, omega-3) | 2.68 g | 0.76 g | no DV |
| Vitamin E (alpha-tocopherol) | 2.08 mg | 0.59 mg | 4% |
| Magnesium | 201 mg | 57 mg | 14% |
| Phosphorus | 513 mg | 145 mg | 12% |
| Zinc | 3.37 mg | 0.96 mg | 9% |
| Copper | 1.36 mg | 0.39 mg | 43% |
| Manganese | 3.90 mg | 1.1 mg | 48% |
| Selenium | 17 mcg | 4.8 mcg | 9% |
| Potassium | 523 mg | 148 mg | 3% |
Source: USDA FoodData Central, "Nuts, walnuts, black, dried" (FDC 170186). [1] The USDA household portion is 1 ounce (28.35 g); one cup chopped is 125 g. % Daily Value uses the FDA 2016 Daily Values; values vary with variety, growing place, roasting and storage.
Compared with English walnuts. USDA lists English walnuts (Juglans regia) at 654 kcal and 15.2 g protein per 100 g; black walnuts are 619 kcal and 24.1 g protein, so an ounce of black walnuts has more protein and a little less energy. Black walnuts list 2.68 g of ALA per 100 g, while English walnuts are the nut usually named as an ALA source. See Walnuts. The English walnut figures are from the USDA data used on that page; we did not re-read that USDA page here.
Plant compounds. The main fat is polyunsaturated (36.4 g per 100 g, of which linoleic acid is 33.8 g). [1] We did not read a source that measured plant compounds in the black walnut kernel itself. A 2024 laboratory study profiled polyphenols in black walnut bark, leaf and pericarp (the outer husk layers), not the kernel, and tested them on cells in the lab; that is lab-only evidence and says nothing about eating the nut. [10]
What research says
| Health goal | What the sources found | Strength of evidence | What was studied |
|---|---|---|---|
| Blood cholesterol and triglycerides | A pooled analysis of 26 trials (1,059 people) found English walnut-enriched diets lowered total cholesterol by 6.99 mg/dL and LDL by 5.51 mg/dL. [9] A pooled analysis of 61 tree nut trials (2,582 adults) found lower total and LDL cholesterol, ApoB and triglycerides. [7] Black walnuts were not among the nuts listed in either. | Promising but limited for walnuts and tree nuts; no evidence for black walnuts specifically | English walnuts and mixed tree nuts, whole nuts; blood tests, not heart attacks |
| Body weight | A pooled analysis of 33 nut trials found no significant effect of nut-enriched diets on weight, BMI or waist. [8] | Mixed to reassuring (not black-walnut specific) | Mixed nuts |
| Blood pressure | The English walnut pooled analysis found no significant change in systolic or diastolic pressure. [9] | No good evidence of benefit | English walnuts |
| Heart attacks, memory, cancer, blood sugar, other diseases | We did not find trials of black walnuts as food for these. Proper evidence not found in the sources we read. | Insufficient evidence | none |
| Polyphenols in black walnut bark, leaf and husk | Compounds were profiled and tested on human cancer cells in the lab. [10] | Lab or animal only (not the kernel) | Cell studies |
Eaten as food versus other forms. The trials above used whole nuts as food. Black walnut hull, bark or leaf products and extracts are different products and were not part of those trials. We did not read any trial of them. Funding statements were not shown in the abstracts we read, so we cannot say whether the nut industry paid for them. An observational link (people who eat nuts are healthier) is not proof that nuts caused it.
How much is a normal serving
The USDA household portion is 1 ounce (28.35 g), with about 175 kcal. [1] This is the figure from the USDA file, not a prescription. The 61-trial analysis standardized results to one 1-ounce (28.4 g) serving a day and saw stronger cholesterol effects at 60 g a day or more. [7] How much to eat is a choice for you and your clinician or dietitian. USDA values are for dried black walnuts; roasted, salted, candied or coated nuts differ, so read the label. Black walnuts are often described as having a stronger, more distinct flavor than English walnuts; we did not read a source that measured this, so treat it as a common description rather than a finding. We do not cover foraging, cracking or processing wild nuts here.Safety, allergy and medicines
- Tree nut allergy. The NHS names walnuts among the tree nuts that can cause food allergy; symptoms include hives, swelling of the lips, face and eyes, wheezing or breathlessness, and they can start right away or days later. [3] MedlinePlus says tree nut allergies tend to last a lifetime, and severe reactions can start right away or within two hours. [4] See nut and seed allergy basics.
- Walnut, pecan and other nuts. A review says walnut and pecan are highly cross-reactive, as are cashew and pistachio, and that the current guideline after one tree nut allergy is strict avoidance of all tree nuts; the extent of cross-reactivity among other tree nuts is unclear. [2] We found no study that tested black walnut specifically, so we cannot say how closely it matches English walnut. An allergist can say which nuts you can eat.
- Labels. Under U.S. law the type of tree nut (for example almonds, pecans, walnuts) must be declared on food labels. [5] We did not read whether products made from black walnuts are labeled "walnuts".
- Peanut is a different allergy. Peanut is a legume, not a tree nut. We did not read a source on how often the two overlap.
- Emergency. For wheezing, trouble breathing or swallowing, or swelling of the face, lips or tongue after eating, call 911 or your local emergency number; use prescribed epinephrine first. [4]
- Choking in young children. The CDC lists whole or chopped nuts and seeds, and thick clumps of nut spreads, as choking hazards for young children. [6] See foods for babies and toddlers.
- Calories. One ounce is about 175 kcal. [1] A pooled analysis of nut trials found no significant weight gain with nut-enriched diets. [8]
- Medicines and kidneys. We did not find a source we could read about medicine interactions or kidney-diet limits for black walnuts as food, so we make no claim either way. A pharmacist can check. See foods and medicine interactions.
Choosing, storing and food safety
- We did not read an official source on rancidity or mold specific to black walnuts. For storage, mold and aflatoxin basics, see storing nuts and seeds.
- Check the label for added salt, sugar or flavorings and for allergy warnings about shared equipment.
Related pages
Health connections for Black Walnuts
What research links to eating or drinking this food, and how strong the evidence is. Many studies are observational or use juice, powder, oil or extracts rather than the food as eaten; each card says which.
Manganese, copper and magnesium
Established roleOne ounce gives about 48% of the manganese, 43% of the copper and 14% of the magnesium Daily Value, by USDA data.
Supplements: Applies to the whole food.
Protein and fat profile
Established roleOne ounce has about 6.8 g protein and 16.8 g fat, mostly polyunsaturated, with 0.76 g ALA.
Supplements: Applies to the whole food.
Tree nuts and LDL cholesterol (not tested in black walnuts)
Preliminary or mixedPooled trials of English walnuts and of tree nuts overall found lower LDL cholesterol; black walnuts were not among the nuts tested.
Supplements: Trials used whole nuts as food; no black walnut trials found.
Nuts and body weight
Preliminary or mixedA pooled analysis of 33 nut trials found no significant effect on weight, BMI or waist.
Supplements: Mixed nuts as food; not black-walnut specific.
Energy density
Established roleAbout 175 kcal in one ounce (28 g).
Supplements: Applies to the whole food.
Plant compounds in black walnut bark, leaf and husk
Lab or animal research onlyPolyphenols were profiled and tested on cells in the lab. These are not kernel results.
Supplements: No supplement trial read.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Body systems (1)
- Immune SystemDocumented risk
Tree nut allergy is an immune reaction and can be life-threatening; walnut and pecan are highly cross-reactive.
Body parts (1)
- Immune SystemDocumented risk
Allergic reactions to tree nuts involve the immune system.
Habits (1)
- Balanced NutritionEstablished role
A whole nut that supplies fats, protein and minerals such as manganese and copper per USDA data; this is not a claim of treatment.
Conditions & symptoms (2)
- Food AllergyDocumented risk
Black walnut is a walnut-group tree nut; tree nut allergy can be severe and tends to last a lifetime.
- Food AnaphylaxisDocumented risk
Call 911 for trouble breathing or swelling after eating nuts.
Documented risks and interactions (3)
- Tree nut allergy and walnut-pecan cross-reactivity. Tree nut allergy can be life-threatening and is rarely outgrown. Walnut and pecan are highly cross-reactive; no black walnut allergen study was found.
- Severe allergic reaction (emergency). Trouble breathing or swelling of the lips, mouth or throat needs 911 or the local emergency number.
- Choking in young children. Whole or chopped nuts and thick nut spreads are choking hazards for young children.
Frequently asked questions
How are black walnuts different from regular walnuts?
They are a different species (Juglans nigra versus J. regia). By USDA data, an ounce of black walnuts has about 6.8 g protein and 175 kcal. [1] Almost all the cholesterol research we found used English walnuts. [9]
Do black walnuts lower cholesterol?
No trial of black walnuts as food was found in the sources we read. Pooled trials of English walnuts and tree nuts overall found lower LDL cholesterol. [7][9]
If I am allergic to walnuts or pecans, can I eat black walnuts?
Not without advice. Walnut and pecan are highly cross-reactive, and the guideline after a tree nut allergy is avoiding all tree nuts. [2] Call 911 for trouble breathing or swelling. [4]
Are black walnuts high in calories?
Yes, they are energy dense: about 175 kcal per ounce (28 g). [1] Pooled trials found nut-enriched diets did not raise body weight significantly. [8]
Are black walnuts safe for toddlers?
Whole or chopped nuts and thick nut spreads are choking hazards for young children, says the CDC. [6]
References
- U.S. Department of Agriculture. FoodData Central: Nuts, walnuts, black, dried (SR Legacy, FDC 170186). April 2018 release. Read 2026-10-23.
- Tree nut allergies: Allergen homology, cross-reactivity, and implications for therapy. Clin Exp Allergy 2018. PMID 29700869. Abstract read 2026-10-23.
- NHS (UK). Food allergy. Read 2026-10-23.
- MedlinePlus. Food allergy. Read 2026-10-23.
- U.S. Food and Drug Administration. Food Allergies. Read 2026-10-23.
- Centers for Disease Control and Prevention. Choking hazards for young children. Read 2026-10-23.
- Del Gobbo LC et al. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. Am J Clin Nutr 2015. PMID 26561616. Abstract read 2026-10-23.
- Flores-Mateo G et al. Nut intake and adiposity: meta-analysis of clinical trials. Am J Clin Nutr 2013. PMID 23595878. Abstract read 2026-10-23.
- Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials. Am J Clin Nutr 2018. PMID 29931130. Abstract read 2026-10-23.
- Comprehensive Characterization of Phytochemical Composition, Membrane Permeability, and Antiproliferative Activity of Juglans nigra Polyphenols. Int J Mol Sci 2024. PMID 39000038. Abstract read 2026-10-23.