IngredientsJuglans cinerea, the botanical name assigned by Linnaeus, is a deciduous nut-producing tree of the walnut family (Juglandaceae), native to eastern North America. It is most widely known under two common names: butternut and white walnut. Additional vernacular names recorded in pharmacopoeial and trade literature include lemon walnut, oil nut, noyer cendré (French), noyer blanc, noyer à beurre, nogal blanco americano, and butternussbaum (German).
The genus name Juglans is derived from two Latin words — Jovis (Jupiter) and glans (acorn or nut) — while the specific epithet cinerea is translated as "gray," referring to the distinctive bark of the tree. Historical botanical synonyms used in older pharmaceutical texts include Wallia cinerea and Nux cinerea.
The evolutionary origin of J. cinerea has recently become clearer; phylogenomic analysis suggests that it is the result of massive introgression from a member of the J. mandshurica lineage into a member of the black walnut lineage, 0.6–0.9 million years ago.
Juglans cinerea is a deciduous tree growing to 30 metres (98 ft) tall, rarely more. It is a slow-growing species and rarely lives longer than 75 years. It has a stem diameter of 40–80 cm, with light gray bark.
The leaves are alternate and pinnate, 40–70 cm long, with 11–17 leaflets, each leaflet 5–10 cm long and 3–5 cm broad. Leaves have a terminal leaflet at the end of the leafstalk and have an odd number of leaflets. The whole leaf is downy-pubescent, and a somewhat brighter, yellower green than many other tree leaves.
The species is monoecious; male flowers are single-stemmed, yellow-green catkins, 2½ to 5½ inches long; female flowers are on a short spike near the end of the twig, green-yellow in color, and appear in mid to late summer. The fruit is oblong (lemon-shaped), with a yellow-green sticky indehiscent husk; the husk contains an irregularly ribbed nut containing sweet, oily meat; it matures in late summer.
It is native to moist bottomlands, lowland forests, and some drier limestone soils in eastern and midwestern North America, from New Brunswick to Minnesota, south to Georgia and Arkansas.
The part used medicinally is the bark of the root of Juglans cinerea, traditionally collected in the autumn. In phytomedicinal practice, the inner bark of the stem is also used. Traditional herbalists prepared a decoction or tincture from the bark for medicinal purposes. Historic pharmaceutical preparations included Extractum Juglandis Fluidum (fluid extract of Juglans), dosed at one minim to one-half dram, and Tinctura Juglandis (tincture of Juglans). A "Specific Medicine Juglans" preparation was also in use, prescribed in doses of ten drops to one-half dram in four ounces of water, taken every one, two, or three hours. The isolated resinoid constituent juglandin was dosed from one-fifth of a grain to one grain.
In contemporary commerce, J. cinerea bark is available as loose dried herb for decoctions, encapsulated powder, and alcohol-based tinctures. Butternut bark may be taken as a tea or powdered for capsules; chopped bark can also be tinctured.
Juglans cinerea has long held cultural importance among Indigenous peoples of eastern North America, particularly as a valued food source and element of traditional practices. In the Mohawk language, it is called Akiehwa:ta, referring to its edible oil-rich nuts, which were harvested rapidly upon ripening to prevent rancidity and incorporated into the diets of many First Nations groups. The Haudenosaunee (Iroquois Confederacy) contributed to its wider distribution by planting butternuts near villages and facilitating trade of the nuts among Native communities, which sustained scattered populations beyond the tree's primary range.
For the Abenaki people, the butternut represents the archetype of nut trees, with its nuts, bark, leaves, and husks traditionally used for food, medicine, and natural dyes, underscoring its enduring role in cultural heritage and ecological knowledge.
Butternut was used by various Native North American Indian tribes as a laxative and tonic remedy to treat a variety of conditions including rheumatic and arthritic joints, headaches, dysentery, constipation, and wounds. In Appalachia, an oil expressed from fresh butternuts was used to expel tapeworms.
Butternut bark occupied a significant place in 19th- and early 20th-century American botanical and Eclectic medicine. King's American Dispensatory (Felter & Lloyd, 1905) describes medicinal uses of the root bark as a cathartic and for other conditions. The inner bark, especially that obtained from the root, was considered one of the most mild and efficacious laxatives of the era, and was commonly employed in the form of an extract kept in druggists' shops. Ten or twelve grains of this extract operated gently, and twenty or thirty grains with considerable activity on the bowels.
Finley Ellingwood's American Materia Medica, Therapeutics and Pharmacognosy (1919) recorded that experiments with the drug ascertained that it influences the liver, small intestines, colon, and rectum, causing increased manufacture and elimination of bile as well as increased activity of the glands of the intestinal tract. Full doses were observed to produce large bilious evacuations without much pain or griping.
Eclectic physicians recorded the specific indications as: chronic constipation; gastrointestinal irritation with sour eructations, flatulence, and either diarrhea or constipation dependent thereon; diarrhea and dysentery with tenesmus and burning, fetid discharges; hepatic torpor; and chronic pustular or vesicular skin disease.
A full laxative dose of extract of butternut was a favored early-day treatment of malarial infection or "ague" in the western states, where pioneers also used it for rheumatic pain in the back.
The tree is economically important locally for its edible nuts and for a yellow or orange dye obtained from the fruit husks. A yellow to orange dye is obtained from the seed husks and from the bark. Some substances in the inner bark of the roots are used in medicines.
The phytochemistry of Juglans cinerea overlaps substantially with other members of the Juglandaceae family. The principal constituents identified in historical and modern sources include the following:
Juglone is the most prominent ingredient in different organs of the walnut tree, with a molecular weight of 174.16 and formula C₁₀H₅O₂(OH); its precursor is a glycoside found in aerial parts of the plant, especially leaves, which is converted to juglone through hydrolysis.
Juglone belongs to the class of naphthoquinones — natural products with high antibacterial activity. It has been used for centuries in folk medicines to cure acne, allergies, gastrointestinal disorders, intestinal parasitosis, cancer, fungal infections, bacterial infections, and viral infections.
The mechanisms by which juglone exerts its biological effects are multiple and partially understood from in vitro and preclinical work:
Important framing note: There are no published controlled clinical trials specifically investigating the efficacy of Juglans cinerea preparations in human subjects. Despite its historical usage, there is limited scientific research available to validate the effectiveness of butternut bark in human conditions. No large-scale clinical trials have confirmed its safety or efficacy; most of the available evidence is anecdotal or comes from historical texts and herbal compendia. The scientific evidence reviewed below pertains primarily to the isolated constituent juglone, studied in vitro (cell culture) and in animal models. This evidence must not be conflated with clinical evidence in humans for J. cinerea preparations.
In small doses, juglans was described as a mild intestinal stimulant and laxative; in large doses it was emeto-cathartic. It also possessed alterative properties. As a laxative its action was described as kindly, rarely producing griping or after-debility, and resembling that of rhubarb without producing subsequent constipation.
Butternut is categorized as a stimulant laxative; stimulant laxatives can decrease potassium levels in the body. In modern herbalism, J. cinerea is considered a remedy for chronic constipation, gently encouraging regular bowel movements. However, these characterizations are based on traditional observation and clinical descriptions from the 19th-century Eclectic tradition rather than controlled trials. More evidence is needed to rate the effectiveness of butternut for these uses.
The antimicrobial activity of juglone has been investigated in vitro. Juglone is a plant-derived 1,4-naphthoquinone with confirmed antibacterial and antitumor activities. Research has demonstrated that juglone shows antibacterial activity against S. aureus, Escherichia coli, Bacillus subtilis, Penicillium sp., Aspergillus sp., and Hansenula sp. Despite its evidenced beneficial herbicidal, antibacterial, antiviral, antifungal, and antioxidant effects, the application of juglone is limited due to its low water solubility and allelopathic and toxic effects.
Evidence strength: In vitro (preclinical) only. No human clinical data exist for J. cinerea preparations in infectious conditions.
Walnuts contain the phenolic compound juglone (5-hydroxy-1,4-naphthoquinone), which has antiparasitic, anti-inflammatory, immunoregulatory, and antioxidant properties. In a murine study of Schistosoma mansoni infection using three groups (untreated, juglone-treated, and praziquantel-treated), in mice treated with 8 mg juglone/kg body weight a reduction of 63.1% and 52.1% was observed in the number of male and female worms, respectively. The number of eggs/g tissue was reduced by 65.7% in the liver, 58.58% in the intestine, and 62.31% in the liver and intestine combined.
Juglone has occasionally been used as an herbicide and an anthelmintic (antiparasitic agent).
Evidence strength: Animal model (murine) only for parasitic disease. No controlled human clinical data.
Multiple in vitro studies have examined juglone's cytotoxic properties across cancer cell lines. These investigations relate to juglone as an isolated compound found across Juglandaceae species, including J. cinerea.
Evidence strength: All anticancer evidence is in vitro (cell culture) only. There are no human clinical trials investigating J. cinerea or juglone preparations as cancer treatments in humans.
A study explored the effects of juglone on NLRP3 inflammasome activation; its inhibitory effects on nitric oxide production were assessed in LPS-stimulated J774.1 cells, along with its effects on reactive oxygen species and NLRP3 ATPase activity, and the expression levels of NLRP3, caspase-1, and pro-inflammatory cytokines (IL-1β, IL-18). Juglone was non-toxic in J774.1 cells when used at 10 μM, and treatment inhibited the production of ROS and NO.
Evidence strength: In vitro (cell culture) only. No human clinical evidence.
An infusion of the inner bark has been used as a cholagogue, febrifuge, mild laxative, and stomachic. Butternut has also been credited with lowering cholesterol levels and promoting the clearance of waste products by the liver, a claim originating from traditional herbal literature rather than clinical research. No controlled human clinical trials have been identified evaluating these hepatic or cholagogue effects.
Juglans cinerea was reported in Eclectic medical texts to be curative of a variety of skin diseases, whether scaly or pustular, whether characterized by papules or bullae, so long as the lesion was associated with some disorder of digestion and assimilation. It was also used both locally and internally for chronic and ill-conditioned ulcers, stimulating waste and improving nutrition. These characterizations are historical, based on clinical observation within the Eclectic tradition, and are unsupported by modern controlled studies.
Based on documented traditional use and available (primarily preclinical) research, Juglans cinerea has been associated with the following body systems:
The following dosage forms and amounts are drawn directly from historical pharmaceutical texts and preclinical studies, as no modern standardized human clinical dosing has been established:
No modern standardized therapeutic dose for human use has been established through controlled clinical trials.
When taken by mouth, butternut is possibly safe for most people, but it can cause diarrhea and irritation of the stomach and intestines.
In large amounts, butternut is likely unsafe during pregnancy or breast-feeding, as it may stimulate the bowels too much. Note that some older herbal literature (e.g., PFAF citing reference [301]) suggests the inner bark is one of the few laxatives considered safe in pregnancy, but this claim does not derive from controlled clinical study and conflicts with the pharmacological concern about excessive bowel stimulation.
Butternut is a type of stimulant laxative; stimulant laxatives can decrease potassium levels in the body, and low potassium levels can increase the risk of side effects of digoxin (Lanoxin). Some medications for inflammation can decrease potassium in the body; butternut, as a stimulant laxative, may also decrease potassium, compounding this effect.
Butternut should not be used if a person has gallstones. This caution is reflected in traditional and modern herbal reference texts.
Despite its evidenced beneficial effects, the application of juglone is limited due to its low water solubility and allelopathic and toxic effects. In one study, mouse and plant cells treated with free juglone showed a decrease in cell viability in a dose- and time-dependent manner. The dual nature of juglone — exhibiting both cytotoxic effects on cancer cells and potential general cytotoxicity — underscores the need for caution in its use and for further research defining safe therapeutic windows.
As a member of the Juglandaceae (walnut family), individuals with documented tree nut allergies should be aware of potential cross-reactivity, consistent with general guidance applicable to all members of this botanical family.
Juglans cinerea, native to the Eastern United States and Southeastern Canada, is currently listed as Endangered on the IUCN Red List due to decline from an invasive fungus known as Ophiognomonia clavigignenti-juglandacearum that causes butternut canker. The disease had already killed more than 80% of butternut trees in numerous states by the 1990s and is threatening the species with extinction. Butternut was assessed by Canada's Committee on the Status of Endangered Wildlife (COSEWIC) and subsequently listed as Endangered under the Species at Risk Act. The U.S. Forest Service placed a moratorium on cutting healthy butternut trees in National Forests as of March 1993. These conservation pressures are directly relevant to the raw-material supply of any commercial herbal preparation derived from wild-harvested J. cinerea bark.
Across all areas of claimed activity, the evidence base for Juglans cinerea as a dietary supplement or herbal medicine is weak to absent at the clinical level. The primary bases for its use are: (1) a well-documented ethnobotanical and 19th-century Eclectic medical tradition for laxative, hepatic, and anti-infective use; and (2) preclinical (in vitro and animal model) research on juglone, an isolated constituent found across the Juglandaceae family. No randomized controlled trials, systematic reviews, or regulatory approvals (e.g., from the German Commission E, ESCOP, or EMA) have been identified for J. cinerea specifically. The compound juglone has been the subject of more rigorous pharmacological investigation, but all such work remains at the preclinical stage and cannot be directly extrapolated to oral administration of butternut bark preparations.
Health conditions that Juglans cinerea may help support.
Body systems that Juglans cinerea may help support.
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