Taxonomic Class

Juglandaceae

Common Trade Names

None known.

Common Forms

Available as a decoction, an extract, and a tincture and used externally as a bath additive and a compress.

Source

The leaves of the deciduous tree (Juglans regia), the bark, the hull of the nut, and the nut itself have been used for various preparations.

Chemical Components

The leaves contain about 10% tannins of the ellagitannin type; naphthalene derivatives, especially the monoglucosides of juglone (=5- hydroxy-1,4-naphtholquinone) and hydrojuglone; more than 3% flavonoids (such as quercetin, quercitrin, hyperoside, and kaempferol derivatives); 0.8% to 1% ascorbic acid, plant acids, including gallic, caffeic, and neochlorogenic acids; and 0.001 % to 0.03% volatile oil, mainly germacrene D. The main active components are the tannins and juglone.

Actions

J. regia is mainly used externally as an astringent, based on its tannin content (10%). Juglone and the essential oils may have in vitro antifungal activity and, possibly, antitumorigenic effects in mice. The actual nut has been studied as a substitute (replacing 20% to 35% of monounsaturated fat foods) in cholesterol-lowering diets with success in further reducing total cholesterol and LDL levels in human subjects .

Reported Uses

Walnut preparations have been used externally for acne, eczema, eyelid inflammation, excessive perspiration of the hands and feet, pyodermia, tuberculosis, and various skin ulcers. It has been used internally for catarrhs of the GI tract and as an anthelmintic and a blood-purifying agent.

Dosage

Dosing is highly dependent on various factors. Because no standard production exists, dosage ranges must be viewed as relative guidelines.

External: 3 to 6 g/day; 100 g per full bath.

Extracts: 2 to 3 g P.O. once to several times a day.

Tincture: 1 to 3 ml P.O. once to several times a day.

Adverse Reactions

Hepatic: hepatotoxicity (caused by tannin content).

Other: carcinogenic effects (potential with long-term use of J. regia as an external preparation).

Interactions

None reported.

Contraindications and Precautions

Excessive oral ingestion and topical application of walnuts should be avoided in pregnant or breast-feeding patients.

Special Considerations

• Caution the patient who is at risk for heptatotoxicity about ingesting considerable quantities of walnut because the tannin content may increase the risk of hepatic injury.
• Advise the patient who is looking for a natural agent to reduce serum cholesterol levels to pursue more stringently studied and proven alternatives.
• Inform the patient that walnut preparations that contain juglone compounds can discolor the skin or mucous membranes yellowish brown.
• Caution the patient that daily topical application of walnut preparations may increase the risk of tongue cancer and leukoplakia of the lips.

Commentary

Little, if any, evidence exists other than in vitro studies to support most of the claims for the use of walnut. Larger human trials are needed to demonstrate its effectiveness in hypercholesterolemic men and Women. More research is needed before definitive recommendations can be put forward.

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