What is Black Walnut?
Walnut is an extremely versatile tree. It's best known for its dark and decorative wood, often used as flooring, furniture, and for the stocks of guns and knives.
The green seed husks are boiled to make a yellow dye, and the nut makes a delicious and highly nutritious meal. The oil from this nut is useful as a polish for wood and as a mixer for paint. It's also been used as lamp oil and for cooking purposes.
The medicinal content of the wood is strong, offering powerful astringent activity, and purgative action. The strongest medicinal uses of this tree, however, are in its seed husks, especially while green and unripe.
The chemicals contained in these unripe husks, particularly the chemical juglone, is a powerful destroyer of worms and other parasites. When applied as a salve or balm it is useful for reducing sweating of the hands and feet, and can be used to treat fungal and parasitic infections on the skin such as athletes foot or ringworm.
The anti-parasitic action works if employed in the garden as a strong infusion of the husks or leaves as well to destroy worms or other insects and won't injure the grass. In the wild, it's been found that no insects will touch the leaves or bark of this plant.
What is Black Walnut Used For?
All parts of the tree are antimicrobial, and are used to treat bacterial, and parasitic infections. The green seed husks of Juglans nigeria are highly astringent, and are used to astringe the skin and digestive tract to reduce gut permeability or treat hyperhydrosis. The seed husks are also potent anti-parasitics and are useful in combination for removing parasites from the gastrointestinal tract.
Traditional Uses of Black Walnut:
Culpepper suggests its bark is a great astringent, stating that it "doth bind and dry very much". He also states that the older, more bitter leaves are useful for killing broad-worms in the stomach. The nuts, and leaves are suggested for poison, snakebites, or dog bites. [4].
He also suggests the green husks, boiled with honey is a great remedy for sore throats and inflammations of The mouth and stomach. [4].
In Iran, walnut is often used as an extract and its hydrosol to control blood sugar [2, 3].
In southern Morocco, the leaves are used in the treatment of hypertension and diabetes [11].
+ Traditional Chinese Medicine
(Walnut kernel)
Pinyin:
Hu Tao Ren
Taste:
Sweet [22]
Energy:
Warm [22]
Channels:
Kidney, lung, large intestines [22]
Actions:
Tonifies kidneys, warms the lungs, moistens the intestines [22]
Indications:
Coughs and asthma due to deficiency-cold, constipation due to dry intestines [22]
Cautions:
Do not use with excess fire due to yin deficiency, coughs due to phlegm heat and with loose stools [22]
Herb Details: Black Walnut
Herbal Actions (Nut/Husk):
- Stimulating Hepatic
- Alterative
- Anthelmintic
- Diaphoretic
- Anti-inflammatory
- Antifungal
- Hypoglycemic
- Anti-cancer
- Hypocholesterolemic
- Hypotensive
Herbal Actions (Bark and Leaves):
- Alterative [1]
- Laxative [1]
- Astringent [1, 10]
- Antidiarrhea
- Detergent [1]
- Purgative (Bark)
- Antiseptic
- Anthelmintic [1]
- Stimulant [1]
- Digestive tonic [1, 10]
- Insecticidal [1]
- Hypoglycemic
- Hepatoprotective [12-17]
- Antifungal
- Anticancer [1]
- Antihypertensive (leaves) [10]
- Antioxidant [1, 10, 17]
- Hypocholesterolemic [1, 3, 10]
Part Used
Leaves, Bark, Fruit Husk
Family Name
Juglanaceae
Distribution
Walnut trees grow throughout the temperate zones of the world from North America, to Europe, to the Himalaya mountain range of Asia.
Constituents of Interest
- Juglone
- Volatile oil
- Tannins
Common Names
- Walnut
- Black Walnut
- English Walnut
- Hu Tao Ren (China)
- Persian Walnut
- Butternut
Botanical Description:
The walnut tree is an enormous deciduous tree, reaching heights of 40-60 feet, and have very large, spreading tops. The trunk is very thick, and can reach over 20 feet in circumference. [6].
The walnut genus (Juglans) is part of the Juglandaceae family of plants, which are characterised by large, aromatic leaves, and catkin flowers. This family has about 10 genus' and roughly 50 species.
Other noteable members of this family include:
Carya illinoinensis (Pecan)
Carya spp. (Hickory)
The walnut family has several important members:
Juglans regia (Persian walnut/ English walnut)
Juglans nigra (Black Walnut)
Juglans cinerea (Butternut)
Habitat Ecology, & Distribution:
Juglans species are found primarily in temperate areas and are cultivated commercially throughout southern Europe, Northern Africa, eastern Asia, the United States, and western South America [10]. It is in fact the most widespread tree nut in the world [18].
In the Himalaya, the walnut inhibits mountain slopes at elevations of 1200 - 2100 m (4000 to 7000 feet) [5].
Pharmacology & Medical Research
+ Diabetes
Juglans regia (English walnut) extracts were shown in an experimental study to significantly reduce blood glucose, glycosylated hemoglobin, LDL, triglycerides, and total cholesterol, as well as significantly increase insulin and HDL levels [1, 3]. The mechanism of action is suggested to be through stimulation of the beta-cells of the pancreas to release insulin, increase in the sensitivity of the cells to insulin, or interfere with dietary carbohydrate absorption [1, 8, 9].
If the first suggestion is true (stimulates the beta-cells of the pancreas to secrete insulin), then this action will not work on those with type 1 diabetes, as this condition means that most of the insulin-secreting beta-cells are absent. Since the majority of the study on this herb in this area are conducted on type 2 diabetic models, it's hard to understand how this will affect those lacking beta cells.
Other studies have found similar results [10].
+ Cancer
The leaves of the walnut tree contain a high amount of cancer-fighting polyphenols. These chemicals are well known to possess antioxidant and anti-inflammatory actions, both of which have a direct benefit in treating or preventing cancer cell lines [1].
Walnut hull extracts were found to contain a chemical called ellagitannins, which possess anti-cancer benefits, as well as anti-inflammatory actions [1, 4].
As a bi-product of the walnut oil industry, a large amount of protein is left behind. Part of this protein has been found to possess significant apoptotic actions on cancer cells (MCF-7 cells). The whole protein itself was not responsible for this action, but rather the hydrosylates released via enzymatic processes. Such enzymes that can release these hydrosylates from the chain include pepsin, papain, trypsin, neutral protease, and alkaline protease. Papain-derived hydrosylates were noted to have the most pronounced effect in this regard. The mechanism of action was found to be through the induction of apoptosis and autophagy of the cancer cells and was suggested to offer other immunomodulatory actions as well. [18].
It is currently unclear whether this hydrosylate is produced in the stomach and upper intestines from the pepsin contained within these tissues, or if this will need to be hydrosylated in a lab with commercial enzymes. More research is required.
Other extracts containing triterpene components taken from the green husk of Juglans manshurica were also found to possess anti-cancer activity on hepatic cancer cell lines in vitro (Hep-G2 Cancer cells) [20].
+ Antimicrobial
A Juglans regia bark extract was shown to possess significant antibacterial actions against E. coli and methicillin-resistant S. aureus bacteria but had little to no effect on gram-negative bacteria [21]. This suggests a powerful bactericidal activity of the bark extract of Juglans regia on the gram-positive bacterium, regardless of drug resistance to other antimicrobials, and particularly on Staphylococcus strains.
+ Hepatoprotective
Fibrogenesis of the liver is characterized as an increase in extracellular matrix proteins such as collagen, which are mainly produced in the hepatic stellate cells. This buildup of proteins will lead to a degradation of the hepatic function, and can ultimately lead to death. This reversible condition is an early stage of the more severe and generally non-reversible cirrhosis [12]. Therefore, reducing the activation of these hepatic stellate cells can result in a reduction or prevention of these damaging extracellular matrix protein buildup.
Hepatic stellate cell activation can occur from viral causes such as with HCV, or from drug or other toxic substances that will increase reactive oxygen species in the liver, or cause injury to the parenchymal hepatocytes [12].
The leaves and twigs of Juglans sinensis are known to contain the chemicals oleanene and ursane triterpenes and flavonoids, which have been found to possess therapeutic benefits towards this hepatic fibrosis in both in vitro and in vivo models [12-16].
Another study was done investigating the specific effects of an ethanolic extract of the leaves and twigs of Juglans sinensis on liver injury in vivo. This study found that the extract was able to significantly reverse the pathological parameters associated with this type of liver injury. [12].
Other studies have found that the flavonoids contained within Juglans sinensis suppress reactive oxygen species generation by inhibiting some of the enzymatic activity involved with this free radicle production [17].
+ Hypotensive
Part of the protein portion of the walnut fruit has been found to inhibit the activity of the angiotensin I-converting enzyme (ACE), which has significant activity on the cardiovascular system, namely blood pressure [19].
The perfect ratio of n-6 to n-3 polyunsaturated fatty acids are well known to exert positive effects on the cardiovascular function, including blood pressure regulation as well [18].
+ Nutritive
The fruit of the walnut tree (AKA a walnut) provides high nutritional value. The nut contains a perfect balance of n-6 and n-3 polyunsaturated fatty acids, which has been determined to be a 4:1 ratio, respectively [18].
Phytochemistry
+ Leaves
- Polyphenols
- Volatile oils:
- β-pinene [7]
- β-caryophyllene [7]
- α-pinene [7]
- Germacrene-D [7]
- Limonene [7]
- Homoveratrole [1]
- Piperitone [1]
- Thymol [1]
- Carvacrol [1]
- Eugenol [1]
- γ-eudesmol [1]
- Nonadecane [1]
+ Nut/Husks
- Juglone (5-hydroxy-1, 4-naphthoquinone) (highest in green or unripe husks)
- Oil
- Mucilage
- Albumin
- Minerals
- Cellulose
+ Bark
- Tannins (10%)
- Flavonoids Organic acids Volatile oils
Clinical Applications Of Walnut:
Walnut has a wide range of uses therapeutically. The main use for the green seed husk extracts is as an astringent and anti-parasitic for the gastrointestinal tract and the skin.
The leaves and bark of various species are useful as a hepatoprotective, to lower blood pressure, regulate blood glucose and lower cholesterol and triglycerides, all of which are closely related.
There is an increasing number of trials running with walnut as an adjunctive treatment for cancer.
Cautions
The toxicity of Juglans regia is fairly high, suggested to be 100 times higher than the dose needed to produce antimicrobial actions [21]. Avoid this species and opt for the safer Jugland nigra (black walnut) instead.
Walnut is extremely dangerous to dogs and horses, especially the green seed husks of Juglans nigra due to the high juglone content.
Synergy
For gripping mix with ginger.
For skin eruptions mix with dandelion root.
May have synergy with wormwood for its similar actions against parasitic infections.
Author:
Justin Cooke, BHSc
The Sunlight Experiment
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References:
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