IngredientsUlmus is the genus name for the elms, a group of deciduous trees and shrubs belonging to the Ulmaceae family, comprising around 30 recognized species distributed across the Northern Hemisphere, including U. wallichiana Planchon, U. pumila, U. parvifolia Jacq., U. macrocarpa Hance, U. laevis, U. davidiana, and U. davidiana var. japonica, among others. The genus is naturally distributed throughout the northern hemisphere in Eurasia, North America, and Northern Africa; according to the World Flora Online / Plant List 2024, 44 species are reported as accepted species. The medically and commercially most significant species are profiled below.
Ulmus rubra, the slippery elm, is a species of elm native to eastern North America, with other common names including red elm, gray elm, soft elm, moose elm, and Indian elm. The tree was first named as part of Ulmus americana in 1753, but identified as a separate species, U. rubra, in 1793 by Pennsylvania botanist Gotthilf Muhlenberg. The slightly later name U. fulva, published by French botanist André Michaux in 1803, is still widely used in information related to dietary supplements and alternative medicine. Thus, the full synonymy includes Ulmus fulva Michx., Ulmus americana var. rubra (Muhl.) Aiton, and U. pendula Willd.
The species is native to eastern North America, ranging from southeast North Dakota, east to Maine and southern Quebec, south to northernmost Florida, and west to eastern Texas, where it thrives in moist uplands, although it will also grow in dry, intermediate soils. Ulmus rubra is a medium-sized deciduous tree with a spreading head of branches, commonly growing to 12–19 metres (39–62 ft), very occasionally over 30 m in height.
Ulmus davidiana var. japonica is a deciduous tree native to East Asian countries such as China, Japan, and Korea, and is traditionally used in Korean and Chinese medicine for the treatment of various conditions, including gastric cancer, edema, mastitis, and rheumatoid arthritis. The dried stem and root of the plant are referred to as Yugeunpi.
Ulmus wallichiana Planchon is a tree whose habitat extends from central Nuristan in Afghanistan, traversing Gilgit-Baltistan of Pakistan, and reaching Northern India and western Nepal. It has been utilized as an astringent, demulcent, emollient, expectorant, and diuretic, and its bark has specifically been employed in folk medicine for healing bone fractures in both animals and humans.
Ulmus macrocarpa Hance is an East Asian species that has attracted increasing clinical interest for immune modulation and lipid-lowering effects. It is native to Korea, China, and adjacent regions and has been studied in several modern randomized controlled trials.
Ulmus pumila, the Siberian elm, is a tree native to Asia, also known as the Asiatic elm and dwarf elm. It has been widely cultivated throughout Asia, North America, Argentina, and southern Europe, becoming naturalized in many places.
Different species of Ulmus are used in distinctly different forms depending on cultural and regional tradition:
The common name "slippery elm" is in reference to the slippery-sweet, fibrous, red inner bark that Native Americans peeled from twigs and branches in spring for medicinal use to treat fevers, inflammations, wounds, and sore throat. Strips of the moist bark were also chewed to quench thirst.
Depending on the tribal nation, the inner bark was used in many different ways. For instance, a decoction was traditionally drunk for digestive support by the Menominee, who live near the state now called Wisconsin; they also used the plant topically to cleanse the skin. Other tribal nations consumed slippery elm tea during the last two months of pregnancy to support labor.
Ulmus rubra was used by Native North Americans for digestive complaints, fever, colds, urinary symptoms, and externally for wounds, boils, ulcers, and inflamed eyes. An important medicinal plant of Native Americans, a decoction of the bark was used as a laxative and to aid delivery in childbirth.
American herbalists of European descent primarily used this plant as a nutritive tonic and demulcent. The American Eclectics, for instance, commonly recommended this drink to soothe dry tissues in the lining of the stomach and GI tract. The mucilaginous product functions as a demulcent, or anti-inflammatory agent, and may also serve as a nutritional substitute. During the American Revolution, soldiers found its paste useful as a salve for healing wounds.
Traditionally, slippery elm has been used to relieve the symptoms of indigestion, heartburn and flatulence, sore throats and coughs, to relieve inflammation of the urinary tract, colic, irritable bowel syndrome (IBS), and to treat diarrhoea.
Ulmus davidiana var. japonica Nakai (Ulmaceae) has been used in traditional Korean medicine for chronic inflammation in the gastrointestinal tract. It is reputed to be therapeutically effective against gastric cancer, gastroenteric disorders, tissue granulation and eruption, oedema, rheumatoid arthritis, haemorrhoids, and mastitis. In Korea and China, Ulmus davidiana var. japonica has been used as a traditional oriental medicine for the treatment of difficulty in urination and skin inflammation.
In India, Ayurvedic medicine has a deep tradition of herbal use. Ulmus wallichiana Planchon is one such Ayurvedic herbal medicine, and in and around Kumaon traditional healers use this plant for promoting fracture healing. Extract of U. wallichiana is used as a traditional medicine for rapid fracture repair in India.
Slippery elm inner bark is predominantly composed of dietary fibre including celluloses, lignin, mucilage, and gums. The mucilage consists of long-chain polysaccharides which combine with water to form a viscous, semi-solid mass, and is regarded as the main active constituent. The polysaccharides are composed of D-galactose, L-rhamnose, and D-galacturonic acid and their methylated derivatives and are highly branched. The inner bark of U. rubra contains around 7% mucilage, mainly composed of galactose, rhamnose, galacturonic acid, and 3-O-methylgalactose.
Other constituents include phytosterols, starch, minerals, and oleic and palmitic acids. The bark and its resultant mucilage not only contain anti-inflammatory agents, but also contain nutrients such as vitamin E and bioflavonoids. Slippery elm contains mucilage, which is a complex, sticky substance that can help reduce swelling (inflammation). It also contains chemicals called tannins, which can reduce inflammation by acting as astringents.
Secondary metabolites in the aerial parts of Ulmus plants are generally categorized into catechin glycosides (CG) and flavonoid glycosides (FG).
For Ulmus davidiana var. japonica: Investigations into the phytochemical components of U. davidiana stem bark have resulted in the isolation of (+)-catechin, (+)-catechin rhamnoside, and (+)-catechin apiofuranoside, triterpene esters, sesquiterpene O-naphthaquinones, and lignan and neolignan glycosides. A more recent phytochemical analysis identified a new chromane derivative and 22 known compounds including catechin derivatives, megastigmane glycoside, dihydrochalcone glycosides, flavanone glycosides, coumarins, lignan derivatives, and phenolic compounds.
For Ulmus wallichiana: Ulmus wallichiana Planchon is recognized for its diverse healing characteristics and is reported to be rich in phytochemicals, particularly flavonoids analogous to quercetin, including (2S,3S)-(+)-3′,4′,5,7-tetrahydroxydihydroflavonol-6-C-β-D-glucopyranoside, 6-Glucopyranosyl-3,3′,4′,5,7-pentahydroxyflavone, 6-Glucopyranosyl-4′,5,7-trihydroxyflavanone, and (2S,3S)-(+)-4′,5,7-trihydroxydihydroflavonol-6-C-β-D-glucopyranoside. It is also reported to contain aliphatic hydrocarbons, triterpenes, and various allelopathic compounds such as alnulin, betulin, caffeic acid, catechol, lupenol, ferulic acid, scopoletin, and vanillin.
For Ulmus pumila: A phytochemical study of the leaves of Ulmus pumila L. led to the isolation of 32 compounds, including fourteen flavonoids (flavonols, dihydroflavones, and dihydroflavonols), five terpenoids (megastigmane glycosides and triterpenoids), four sugars, one phenylpropanoid, two phenolic glycosides, two aromatic glycosides, one phenolic, one lignan glycoside, one steroid glycoside, and one fatty acid.
When slippery elm bark powder or a prepared lozenge is swallowed, the mucilage it contains absorbs water and forms a thick, slippery gel. This gel coats the mucous membranes of the mouth, esophagus, stomach, and intestines as it passes through. The coating effect is physical and immediate — it is not dependent on absorption into the bloodstream or any pharmacological action.
The inner bark is rich in mucilage polysaccharides, which form a viscous gel upon hydration. This gel adheres to epithelial surfaces of the oropharynx, oesophagus, and gastrointestinal (GI) tract, exerting a soothing, barrier-forming effect that helps protect mucosal integrity and reduce irritation.
Slippery elm, like the positive control 5-aminosalicylate, was found to have a dose-dependent antioxidant effect and was the most potent of the herbs tested in a biopsy study. The authors concluded that it was a promising candidate for formal evaluation of its therapeutic potential in vivo in patients with IBD and other chronic inflammatory conditions (Langmead et al. 2002).
Mild prebiotic effect — the polysaccharides in mucilage may serve as substrate for beneficial gut bacteria. In vitro and in vivo studies suggest its mucilage content enhances epithelial repair, modulates local inflammation, and may exert a prebiotic effect, favouring the growth of beneficial gut microbiota.
(2S,3S)-Aromadendrin-6-C-β-D-glucopyranoside (AG), a novel flavonol isolated from the extract of Ulmus wallichiana, has potent osteogenic, anti-osteoclastogenic, and anti-adipogenic effects, which may translate to a better skeletal outcome in postmenopausal osteoporosis. This plant exhibits significant therapeutic and economic potential due to the presence of various C-glycosylated flavonoids, which have been thoroughly examined for their characteristics related to osteoporosis and osteoclastogenesis.
Ulmus macrocarpa Hance extract (UME) has demonstrated an antilipidemic effect via upregulation of the adenosine monophosphate-activated protein kinase (AMPK) pathway and regulation of lipid metabolism in both laboratory and animal studies.
Among isolates from the root bark of U. davidiana var. japonica, certain compounds caused a greater increase in the production and activity of nerve growth factor (NGF) in C6 glioma cells, whereas others inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine microglial cells. Additionally, some compounds showed anti-H. pylori activity, and these findings provide scientific evidence that supports the traditional usage of U. davidiana var. japonica root bark in the treatment of gastroenteric and inflammatory disorders.
Ulmus davidiana root extract showed inhibitory activity of PGE2 release in a dose-dependent manner (up to 85.9% at a concentration of 0.1%) in human fibroblast cell lines. The percent inhibition of the release of IL-6 was in the range of 45.6% to 64.5%, and the release of IL-8 was completely inhibited across the entire concentration range tested. In a test of recovery from photo-induced damage after UVA irradiation, the cell recovery of human fibroblasts increased to levels two times higher than the positive control.
Ulmus davidiana var. japonica Nakai has been used in traditional Korean medicine for chronic inflammation in the GI tract. A murine investigation administered oral bark water extract (UDE) at 5 g/kg once daily for 14 days, then analyzed major immune cells in the small intestinal lamina propria, spleen, and mesenteric lymph nodes. This preclinical study represents mechanistic groundwork only and does not constitute clinical evidence.
Overall assessment: Scientific research on medicinal properties of slippery elm is lacking. No published clinical trials investigating slippery elm, other than in combination with other herbs, have been carried out.
IBS — Human evidence (combination formula): A 2008 pilot study published in the Journal of Alternative and Complementary Medicine tested a compound herbal preparation containing slippery elm as a primary ingredient in patients with IBS-C (constipation-predominant) or IBS-D (diarrhea-predominant). After eight weeks, both groups showed improvements in bowel habit consistency, straining, bloating, and abdominal pain. One limitation: the study used a multi-ingredient formula, making it difficult to attribute effects specifically to slippery elm.
IBS — Further combination evidence: A small clinical study showed that a formulation containing slippery elm improved the bowel habits and symptoms of constipation-predominant irritable bowel syndrome. The evidence base for slippery elm in IBS is limited but exists, and is confounded by the multi-herb nature of available trials.
IBD — In vitro evidence: In one study, inflamed colon tissue from ulcerative colitis patients exposed to slippery elm extract produced fewer oxygen free radicals, suggesting a mild antioxidant effect. The bark of slippery elm was suggested to be effective for treating IBD patients owing to its antioxidant effects; however, further studies are needed to confirm its efficacy. This remains pre-clinical evidence only.
Sore throat / upper airway: In the United States, slippery elm is marketed commercially to treat upper airway inflammatory conditions, and its reported benefits in treating these conditions are ubiquitous in anecdotal contexts. Individuals with voice disorders and other inflammatory conditions of the upper airway (e.g., laryngitis) are increasingly seeking information related to its use, although no scientific evidence is available to support the validity of slippery elm's use in treating upper airway inflammatory conditions.
Evidence type: Preclinical animal studies. No published human clinical trials have been found.
One study aimed to determine the skeletal effects of total ethanolic extract (TEE) and its butanolic fraction (BF) from the stem-bark of Ulmus wallichiana, which is rich in C-glycosylated flavonoids, in growing rats (for peak bone achievement) and in ovariectomized rats (for menopausal bone loss). TEE (750 mg/kg/day) and BF (50 mg/kg/day) were given orally for 10 weeks to weaning female Sprague-Dawley rats and for 12 weeks to adult ovariectomized rats, respectively. Bone mineral density, biomechanical strength, bone histology, formations of osteoprogenitor cells, osteoid formation, and bone turnover/resorption markers were studied.
The study concluded that butanolic fraction (BF) derived from U. wallichiana was more effective than total ethanolic extract (TEE) at much lower dose in achieving peak bone and preventing ovariectomy-related bone deterioration.
A subsequent study showed that GTDF (6-C-β-D-glucopyranosyl-(2S,3S)-(+)-5,7,3',4'-tetrahydroxydihydroflavonol), a novel compound isolated from Ulmus wallichiana reported to have bone anabolic action in ovariectomized rats, was studied in the context of glucocorticoid (GC)-induced bone loss. All evidence for U. wallichiana in bone health remains at the animal/in vitro stage.
A 2024 review investigating the therapeutic effects of Ulmus species extracts on bone health and inflammatory conditions analyzed 9,757 studies, narrowing down to 56 pertinent ones. The focus was on catechin glycosides (CG) and flavonoid glycosides (FG). The research highlighted the extracts' role in enhancing bone mineral density (BMD) by stimulating osteoblast activity and suppressing osteoclast differentiation. Furthermore, the extracts demonstrated significant anti-inflammatory properties by modulating inflammatory markers and pathways. The findings confirm the historical use of Ulmus extracts in East Asia for health benefits and recommend further exploration into functional foods and nutraceuticals.
Evidence type: One randomized, double-blind, placebo-controlled clinical trial in humans.
In a double-blind placebo-controlled randomized clinical trial, 80 patients with untreated high LDL-C concentrations (130–190 mg/dl) were randomly allocated to either the "UME group" (received 500 mg UME as two capsules per day) or the "Placebo group" for 12 weeks. The primary outcome was the change in LDL-C concentration; secondary outcomes included changes in total cholesterol (TC), triglyceride, HDL-C, apolipoprotein A1, and apolipoprotein B (ApoB) concentrations.
UME over 12 weeks led to a greater decrease in LDL-C, TC, and ApoB concentrations than did the placebo. Diastolic blood pressure also decreased at 12 weeks in the UME group compared to the placebo group. A study in spontaneously hypertensive rats reported that prolonged (42 days) administration with UME reduced systolic blood pressure, although it is necessary to reconfirm the effect of UME on blood pressure in humans. This is a single, relatively small trial and should be interpreted accordingly.
Evidence type: One randomized, double-blind, placebo-controlled human trial.
Ulmus macrocarpa extract had been shown to have immune-related effects in animals, but no studies had been performed in humans prior to this trial. A randomized, double-blind, placebo-controlled trial was conducted to determine the effect of short-term administration of UME on immune function biomarkers. Among 50 healthy controls treated with a U. macrocarpa extract (500 mg) or placebo once daily for 4 weeks, minor changes occurred in serum cytokine levels but no change in liver function, renal function, or CK were observed in either group. The observed immunological changes were minor, and the trial was small; results should be considered preliminary.
A randomized, placebo-controlled clinical trial examined whether Ulmus macrocarpa Hance extract modulates intestinal microbiota in healthy adults (published in Journal of Microbiology, December 2021). This represents clinical-level evidence, though the trial size and design details require evaluation in context with other emerging evidence.
Compounds isolated from U. davidiana var. japonica showed anti-H. pylori activity with MIC values of 25 or 50 µM against two strains of H. pylori 51 and 43504. This is in vitro evidence only.
In order to investigate the potential of a polysaccharide extract from Ulmus davidiana var. japonica as a cosmetic ingredient, researchers measured its moisturizing effect, photo-induced cytotoxicity, and anti-inflammatory effect. In a moisturizing test, the Ulmus davidiana root extract showed almost the same moisturizing effect as hyaluronic acid. These are in vitro findings.
Bioactivity-driven phytochemical analysis of the root bark extract of Ulmus davidiana var. japonica led to the isolation of 10 compounds including a new coumarin glycoside derivative, ulmusakidian. The isolated compounds were tested for antifungal activity against human fungal pathogens Cryptococcus neoformans and Candida albicans. Compounds 9 and 10 showed antifungal activity against C. neoformans, with the lowest MIC of 12.5–25.0 µg/mL, whereas none of the compounds showed antifungal activity against C. albicans. This is in vitro evidence only.
Important note: No standardized, universally accepted clinical dose has been established for any Ulmus species. Most products rely on traditional use, small studies, or mixed-ingredient formulas rather than a single, standardized clinical dose.
There is no reliable data on adverse events from slippery elm and it is designated as "generally recognized as safe" (GRAS). There have been no large-scale clinical trials that have reported on adverse events associated with use of slippery elm preparations.
Slippery elm preparations are generally recognized as safe and there is no evidence that it can cause elevations in liver-related enzymes or clinically apparent liver injury. Despite common use, there have been no published case reports of liver injury attributed to slippery elm. Large case series of liver injury due to herbal and dietary supplements do not mention or list slippery elm as an implicated cause. Likelihood score: E (unlikely cause of clinically apparent liver injury).
Slippery elm has been linked to rare instances of cutaneous allergic symptoms. In addition to allergic reactions, which are always possible, slippery elm can also slow and/or inhibit absorption of other medications and should therefore be taken 2 hours before or after other medications.
Slippery elm should be taken two hours apart from other oral medications — it can reduce drug absorption. This interaction is attributed to its physical mucilaginous gel-forming properties, which may coat the gastrointestinal epithelium and impede absorption of co-administered drugs. This is a pharmacokinetic, not pharmacodynamic, concern.
Safety data for slippery elm is lacking, so it is not recommended during pregnancy and lactation and in children/adolescents under 18 years of age — this is the conservative position taken in pharmacognosy texts. There are conflicting data regarding the use of slippery elm during pregnancy, but in the most current information on the oral use of slippery elm, it is considered safe for use in pregnancy — though this view represents a more permissive interpretation. Slippery elm should be avoided if pregnant or if the patient has bowel strictures, as its bulking effect could worsen blockage risk.
Among 50 healthy controls treated with Ulmus macrocarpa extract (500 mg) or placebo once daily for 4 weeks, no change in liver function, renal function, or CK were observed in either group. This represents the most rigorous safety reporting available for any Ulmus species in humans, albeit for a short duration.
Slippery elm should be avoided if the patient has bowel strictures, as its bulking effect could worsen blockage risk. The gel-forming mucilage increases stool bulk and water content, which is beneficial in most contexts but represents a theoretical concern in patients with known obstruction or strictures.
Slippery elm is one of the components in Essiac, an herbal formula used as an alternative cancer treatment. The safety and efficacy of Essiac as a cancer treatment have not been established in clinical trials, and its use in oncology settings requires careful consideration of interactions with conventional therapies.
Health conditions that Ulmus may help support.
Body systems that Ulmus may help support.
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