Juglans nigra, more commonly known as black walnut, is a deciduous tree producing nuts rich in protein, essential fatty acids and fiber 1. People also take black walnut as an herbal remedy, typically using an extract from the sticky contents of the outermost hull, according to Drugs.com 1. Black walnut extract is used topically for treating eczema, psoriasis and warts, and internally for eliminating parasites 1. Some alternative practitioners theorize black walnut may be an effective cancer treatment, particularly those who consider parasites to be a cause of this illness 1. Evidence does not support the idea that black walnut hulls eliminate parasites or treat any disease, according to the American Cancer Society 1. The most likely side effect is an allergic reaction.
If you are experiencing serious medical symptoms, seek emergency treatment immediately.
Nut allergies are common in the United States, as explained by Drugs.com, with about 1 percent of people allergic to some type of tree nuts or to peanuts. Peanuts are technically legumes and not true nuts. If you are allergic to walnuts or to any other nuts, especially pecans, you may have a negative reaction to black walnut extract 1. Signs of an allergic reaction to black walnut as listed by PDR Health may include skin itching or swelling, a rash or hives, breathing difficulty, tightness in the chest or throat and chest pain 1. An allergic reaction to black walnut extract should be considered a medical emergency 1. Peanuts and walnuts are the most likely nuts to cause a life-threatening anaphylactic reaction, according to Drugs.com. This shock reaction involves a sudden drop in blood pressure and extreme difficulty breathing.
- Nut allergies are common in the United States, as explained by Drugs.com, with about 1 percent of people allergic to some type of tree nuts or to peanuts.
Topical Side Effects
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Using black walnut extract topically can cause a skin rash, and the substance has cytotoxic properties, or a destructive effect on cells, as noted by Drugs.com 1. PDR Health advises against regular topical use because skin tumors may develop.
Pregnant women should not consume black walnut extract or apply it topically 1. Black walnut components can change the developing baby's genetic material, as explained by Drugs.com, and negative effects have been reported 1.
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- Drugs.com: Black Walnut
- KidsHealth.org: Nut and Peanug Allergy
- Ho KV, Lei Z, Sumner LW, et al. Identifying antibacterial compounds in black walnuts (juglans nigra) using a metabolomics approach. Metabolites. 2018;8(4):58. doi:10.3390/metabo8040058
- Fitschen PJ, Rolfhus KR, Winfrey MR, Allen BK, Manzy M, Maher MA. Cardiovascular effects of consumption of black versus English walnuts. J Med Food. 2011 Sep;14(9):890-8. doi:10.1089/jmf.2010.0169
- Wenzel J, Storer Samaniego C, Wang L, et al. Antioxidant potential of Juglans nigra, black walnut, husks extracted using supercritical carbon dioxide with an ethanol modifier. Food Sci Nutr. 2016;5(2):223–232. doi:10.1002/fsn3.385
- Câmara C, Schlegel V. A review on the potential human health benefits of the black walnut: a comparison with the English walnuts and other tree nuts. International Journal of Food Properties. 2015;19(10):2175-2189. doi:10.1080/10942912.2015.1114951
- Ho KV, Schreiber KL, Vu DC, et al. Black walnut (juglans nigra) extracts inhibit proinflammatory cytokine production from lipopolysaccharide-stimulated human promonocytic cell line U-937. Front Pharmacol. 2019;10:1059. doi:10.3389/fphar.2019.01059
- Guasch-ferré M, Liu X, Malik VS, et al. Nut consumption and risk of cardiovascular disease. J Am Coll Cardiol. 2017;70(20):2519-2532. doi:10.1016/j.jacc.2017.09.035
- BhaduriHauck S. Toxic plant profile: black walnut. University of Maryland Extension. 2015.
Shelley Moore is a journalist and award-winning short-story writer. She specializes in writing about personal development, health, careers and personal finance. Moore has been published in "Family Circle" magazine and the "Milwaukee Sentinel" newspaper, along with numerous other national and regional magazines, daily and weekly newspapers and corporate publications. She has a Bachelor of Science in psychology.