Published June 1, 1990.
List of German Commission E Monographs (Phytotherapy)
Juglandis fructus cortex, walnut hull.
Walnut hull consists of the pericarps of Juglans regia L. [Fam. Juglandaceae], as well as preparations thereof.
Walnut hull preparations are used for catarrhs of the gastrointestinal tract, skin diseases, abscesses, inflammation of the eyes, in combinations for diabetes, gastritis, for "blood purification," blood poisoning, and anemia.
The effectiveness for the claimed applications is not documented.
Fresh walnut hull contains the napthoquinone derivative juglone. The juglone content of the dried walnut hulls has been insufficiently investigated. Juglone acts as a mutagen in various model systems. Application of juglone-containing walnut preparations onto the skin and mucous membranes leads to yellow to brown discoloration. The topical, daily use of juglone-containing preparations of walnut bark is tied to an increased occurrence of cancer of the tongue and leukoplakia of the lips.
Since the effectiveness for the claimed uses is not documented and risks are known, the application of walnut hull preparations cannot be justified.