Related Terms

• American walnut, ellagic acid, Juglandaceae (family), Juglans nigra, juglone, methyl 2-benzimidazolylcarbamate, nogal americano, nogueira-preta, noyer noir, plumbagin, quinones, sesquiterpenes, Schwarze Walnuss (German), tannins.

Background

• Black walnut (Juglans nigra) is a large tree known for its high-quality wood and edible nut which is commonly used as a food ingredient.

• The U.S. Food and Drug Administration (FDA) announced a health claim stating that eating 1.5 ounces per day of walnuts as part of a diet low in fat may reduce the risk of heart disease.

• Black walnut has been shown to contain chemicals called tannins which may help with irritation and may improve tissue firmness. Traditionally, it has been used to relieve constipation and diarrhea.

Scientific Evidence

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

• Acne, antibacterial, anti-inflammatory, antioxidant, antiviral, astringent, cancer, colic, constipation, cosmetic uses (hair dye), diarrhea, eczema, headache, heart disease, herpes, high blood pressure, hyperglycemia (high blood sugar levels), indigestion, insect bites, mood enhancement, mouth sores, parasitic worm infections, skin disinfectant/sterilization, sore throat (gargle), syphilis, toothache, warts, wound care.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (18 years and older)

• Black walnut powder has been taken by mouth as a capsule or tablet, and has also been used on the skin.

Children (under 18 years old)

• There is no proven safe or effective dose for black walnut, and use in children is not recommended.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

• Avoid in patients with known allergy or sensitivity to black walnut, its constituents, including black walnut tree pollen, or to members of the Juglandaceae family. Patients allergic to other nuts may also be allergic to black walnut. Black walnut may irritate the skin.

Side Effects and Warnings

• Black walnut may irritate the skin and may cause stomach upset. When taken for a long time, black walnut may cause mouth or stomach cancer, or liver or kidney damage. Use cautiously in patients with stomach disorders, or liver or kidney conditions.

• Black walnut may alter blood pressure or affect blood vessels. Caution is advised in patients taking drugs, herbs, or supplements that alter blood pressure or compress blood vessels.

Pregnancy and Breastfeeding

• Black walnut is not recommended for pregnant or breastfeeding women due to lack of sufficient data.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

• Black walnut may bind with other drugs when taken at the same time. It is recommended to wait at least two hours before taking any drugs after black walnut.

• Black walnut may alter blood pressure or affect blood vessels. Caution is advised in patients taking drugs that alter blood pressure or compress blood vessels.

• Black walnut may have additive effects with laxatives, antimicrobials, drugs used for the stomach, nausea, inflammation, or cancer, or drugs that harm the liver or kidney.

Interactions with Herbs and Dietary Supplements

• Black walnut may bind with other herbs or supplements when taken at the same time. It is recommended to wait at least two hours before taking any herbs or supplements after black walnut.

• Black walnut may alter blood pressure or affect blood vessels. Caution is advised in patients taking herbs or supplements that alter blood pressure or compress blood vessels.

• Black walnut may have additive effects with laxatives, antimicrobials, herbs or supplements used for the stomach, nausea, inflammation, or cancer, herbs or supplements that harm the liver or kidney, or herbs or supplements that contain chemicals called tannins.

Author Information

• This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Amarowicz, R, Dykes, GA, and Pegg, RB. Antibacterial activity of tannin constituents from Phaseolus vulgaris, Fagoypyrum esculentum, Corylus avellana and Juglans nigra. Fitoterapia 2008;79(3):217-219. View Abstract

2. Choi, HR, Choi, JS, Han, YN, et al. Peroxynitrite scavenging activity of herb extracts. Phytother Res. 2002;16(4):364-367. View Abstract

3. Belknap, JK, Giguere, S, Pettigrew, A, et al. Lamellar pro-inflammatory cytokine expression patterns in laminitis at the developmental stage and at the onset of lameness: innate vs. adaptive immune response. Equine Vet J 2007;39(1):42-47. View Abstract

4. Eaton, SA, Allen, D, Eades, SC, et al. Digital Starling forces and hemodynamics during early laminitis induced by an aqueous extract of black walnut (Juglans nigra) in horses. Am J Vet Res. 1995;56(10):1338-1344. View Abstract

5. Fontaine, GL, Belknap, JK, Allen, D, et al. Expression of interleukin-1beta in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. Am J Vet Res. 2001;62(5):714-720. View Abstract

6. Galey, FD, Beasley, VR, Schaeffer, D, et al. Effect of an aqueous extract of black walnut (Juglans nigra) on isolated equine digital vessels. Am J Vet Res. 1990;51(1):83-88. View Abstract

7. Hurley, DJ, Parks, RJ, Reber, AJ, et al. Dynamic changes in circulating leukocytes during the induction of equine laminitis with black walnut extract. Vet Immunol Immunopathol. 4-15-2006;110(3-4):195-206. View Abstract

8. Inbaraj, JJ and Chignell, CF. Cytotoxic action of juglone and plumbagin: a mechanistic study using HaCaT keratinocytes. Chem Res Toxicol. 2004;17(1):55-62. View Abstract

9. Loftus, JP, Belknap, JK, and Black, SJ. Matrix metalloproteinase-9 in laminae of black walnut extract treated horses correlates with neutrophil abundance. Vet Immunol Immunopathol. 10-15-2006;113(3-4):267-276. View Abstract

10. McConnico, RS, Stokes, AM, Eades, SC, et al. Investigation of the effect of black walnut extract on in vitro ion transport and structure of equine colonic mucosa. Am J Vet Res. 2005;66(3):443-449. View Abstract

11. Moodley, R, Kindness, A, and Jonnalagadda, SB. Elemental composition and chemical characteristics of five edible nuts (almond, Brazil, pecan, macadamia and walnut) consumed in Southern Africa. J Environ Sci Health B 2007;42(5):585-591. View Abstract

12. Qasem, JR. Weed Allelopathy, Its Ecological Impacts and Future Prospects: A Review. Journal of Crop Production. 2001;4(2):43-119.

13. Riggs, LM, Franck, T, Moore, JN, et al. Neutrophil myeloperoxidase measurements in plasma, laminar tissue, and skin of horses given black walnut extract. Am J Vet Res. 2007;68(1):81-86. View Abstract

14. Roux, KH, Teuber, SS, and Sathe, SK. Tree nut allergens. Int Arch.Allergy Immunol. 2003;131(4):234-244. View Abstract

15. von Kiparski, G. R., Lee, L. S., and Gillespie, A. R. Occurrence and fate of the phytotoxin juglone in alley soils under black walnut trees. J Environ Qual. 2007;36(3):709-717. View Abstract