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Herb Reference Guide

Black Walnut

History

The black walnut tree is Native from New England all the way down the east coast and over to Texas. It is a tall deciduous tree reaching heights of up to 75 feet. It is prized for it's timber and has an elegant grain with a very hard yet workable texture making it perfect for furniture making, floors and other fine carpentry including it's use to fabricate gunstock. A 50-foot tree can be valued at up to $2500 for its wood. The nuts provide a robust, distinctive, natural flavor and crunch as a food ingredient. Members of this family of trees produce a chemical called juglone, which is an example of an allelopathic compound, a substance that is synthesized by one type of plant and affects the growth of another. Landscapers have long known that gardening underneath or near black walnut trees can be difficult. Ancient Greeks and Romans called black walnut fruit the “imperial nut” and reportedly used the hull to treat intestinal ailments. Black walnut has also played a part in Russian folk medicine since the seventeenth century. Throughout history, every part of the tree has been used in folk medicine to treat dozens of conditions, including the bite of a mad dog.

Function

The fresh green hulls are used to produce the herbal medicine and are concentrated in the chemical mentioned above; juglone. Since juglone inhibits certain insects, bacteria and fungi in plants and in the black walnut tree itself, researchers have searched for a correlation with its use internally in humans. Many cultures have used Black Walnut hulls to support a healthy intestinal environment and eaten the nuts for their rich Omega 3 essential fatty acid content, vitamin C and flavor. The astringency from the tannins in the hulls and leaves have led herbalists over the years to include Black Walnut in topical applications for the skin.

Uses of Black Walnut

Disclaimer

This information in our Herbal Reference Guide is intended only as a general reference for further exploration, and is not a replacement for professional health advice. This content does not provide dosage information, format recommendations, toxicity levels, or possible interactions with prescription drugs. Accordingly, this information should be used only under the direct supervision of a qualified health practitioner such as a naturopathic physician.

Active Constituents

Juglone (5-hydroxynaphthoquinone), iodine, vitamin C

Parts Used

  • Fresh green hulls

Important precautions

Not for use during pregnancy or lactation. If you have a medical condition or take pharmaceutical drugs please consult your doctor prior to use.

Additional Resources

Feldman EB. J Nutr. 2002;132:1062S-1101S.
McGuffin M, ed. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press; 1997.