Slippery Elm — Ulmus rubra

Common & Latin Names

Common names: Slippery elm, Red elm, Moose elm, Indian elm, Sweet elm, Soft elm Latin name: Ulmus rubra Muhl. (synonym: Ulmus fulva Michx.) Algonquin: Oohoosk (Ojibwe), from which the tree’s medicinal reputation spread through colonial America French-Canadian: Orme rouge

Plant Family & Parts Used

Family: Ulmaceae (elm family) Parts used: Inner bark (phloem/cambium layer) — specifically the mucilaginous inner bark harvested from branches and trunk. The outer bark is discarded. The inner bark can be dried and powdered, prepared as a decoction, or made into lozenges and poultices. Habitat: Native to eastern and central North America, from Quebec to Florida, west to the Dakotas and Texas. Grows in moist, rich soils along riverbanks, floodplains, and lower slopes of hills. The tree can reach 20 meters in height. Unfortunately, slippery elm populations are threatened by Dutch elm disease (Ophiostoma spp.) and habitat loss — sustainable harvesting and cultivation are important conservation concerns.

Traditional Uses

Native American Medicine (Primary Tradition)

Slippery elm is one of the most important medicinal plants in North American Indigenous medicine. Virtually every Eastern Woodland tribe used the inner bark:

• Cherokee: Poultice for wounds, burns, and skin ulcers. Internal decoction for sore throat, cough, and bowel complaints. The bark was chewed during childbirth to ease labor.
• Iroquois (Haudenosaunee): Used the inner bark as a food during famine (it is highly nutritious). Applied as a poultice for abscesses, boils, and infected wounds. Taken internally for dysentery.
• Ojibwe (Chippewa): Inner bark tea for sore throat and cough. Poultice for inflammation. Used in sweat lodge ceremonies.
• Meskwaki (Fox): Slippery elm bark gruel fed to the sick, the elderly, and infants who could not tolerate other food — a recognition of its gentle, nourishing, healing quality.
• Creek and Seminole: Used for GI complaints, as a wound dressing, and as a food supplement.

The bark was also used to make cordage, baskets, and to cover canoes — testifying to its cultural significance beyond medicine.

Eclectic and Physiomedicalist Medicine (19th Century)

Slippery elm was one of the most frequently prescribed remedies in American Eclectic medicine. Felter and Lloyd’s King’s American Dispensatory (1898) devoted extensive passages to Ulmus:

• Internal: Inflammations of the mucous membranes throughout the body — throat, stomach, intestines, urinary tract, vaginal canal
• External: Burns, wounds, abscesses, boils — the powdered bark mixed with water to form a healing poultice
• Nutritive: Slippery elm gruel (bark powder boiled in water or milk) was the standard food for patients too ill to eat — the 19th-century equivalent of an elemental diet
• Rectal: Slippery elm suppositories for hemorrhoids and rectal inflammation

The Eclectics classified slippery elm as a “demulcent” and “emollient” — a soothing, protective agent for inflamed tissues.

Western Herbalism (Modern)

Slippery elm remains a staple of modern Western herbal practice for all conditions involving mucosal inflammation: GERD, gastritis, peptic ulcers, IBD (Crohn’s and ulcerative colitis), IBS, sore throat, and cough. It is frequently combined with marshmallow root and licorice in demulcent formulas.

Active Compounds & Pharmacology

Primary Phytochemicals

Mucilage (the dominant active component, comprising up to 50% of the inner bark by dry weight): A complex mixture of galactose, rhamnose, galacturonic acid, and methylglucuronic acid polysaccharides. When mixed with water, these polysaccharides form a thick, viscous gel — the “slippery” quality that gives the plant its name.

The mucilage is not a single compound but a polysaccharide matrix:

• Galacturonic acid-rich polysaccharides: Structural similarity to pectin. Gel-forming, protective.
• Rhamnose-containing polysaccharides: Immunomodulatory properties.
• Hexose sugars: Provide nutritive value — slippery elm bark is genuinely nourishing, containing usable calories from complex carbohydrates.

Tannins (condensed tannins, proanthocyanidins): 3-6% of bark. Astringent and antimicrobial — complement the demulcent mucilage by toning and protecting inflamed tissue.

Phytosterols: Beta-sitosterol, campesterol. Anti-inflammatory.

Calcium oxalate: Present in the bark; gives the powder a slight grittiness.

Fatty acids: Small amounts of oleic, palmitic, and stearic acid in the bark.

Minerals: Calcium, magnesium, zinc, iron, manganese — contributes to the nutritive quality.

Mechanisms of Action

1. Mucosal Coating and Protection (Bioadhesive Demulcent): The mucilage forms a physical protective barrier over inflamed mucosal surfaces. This gel coats the esophageal, gastric, and intestinal lining, shielding damaged tissue from acid, digestive enzymes, and irritants. The polysaccharides are bioadhesive — they stick to the mucosa rather than simply passing through.

2. Stimulation of Endogenous Mucus Production: Slippery elm does not merely coat the mucosa externally — it stimulates the mucosal goblet cells to increase their own mucus production. This is a critical distinction from simple antacids. The herb triggers the body’s own protective mechanisms via nerve reflex stimulation from the GI tract (the “demulcent reflex” described by physiomedicalist herbalists).

3. Prebiotic Activity: The complex polysaccharides in slippery elm mucilage serve as substrates for beneficial gut bacteria. They are fermented by colonic bacteria to produce short-chain fatty acids (SCFAs), particularly butyrate — the primary fuel for colonocytes and a key anti-inflammatory signal in the gut.

4. Anti-inflammatory (Local): The tannins and polysaccharides reduce local inflammation in the GI mucosa. Tannins precipitate surface proteins, forming a protective layer. The anti-inflammatory effect is primarily local (contact-dependent) rather than systemic.

5. Antioxidant: The proanthocyanidins and polyphenols scavenge free radicals in the GI lumen, reducing oxidative damage to the mucosa.

6. Wound Healing: Applied topically, slippery elm mucilage maintains a moist wound environment (the modern standard for wound healing), provides a physical barrier against infection, and delivers tannins and phytosterols that promote tissue repair.

Clinical Evidence

Key Clinical Studies

Langmead, L., Feakins, R.M., Goldthorpe, S., et al. (2004). “Randomized, double-blind, placebo-controlled trial of oral aloe vera gel for active ulcerative colitis.” Alimentary Pharmacology & Therapeutics, 19(7), 739-747. — While this study focused on aloe vera, the same research group at Barts and The London School of Medicine conducted the related investigation:

Langmead, L., Dawson, C., Hawkins, C., et al. (2002). “Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study.” Alimentary Pharmacology & Therapeutics, 16(2), 197-205.

• Investigated the antioxidant capacity of herbs commonly used by IBD patients, including slippery elm
• Slippery elm bark demonstrated significant antioxidant activity against superoxide radicals (scavenging capacity: 76% at 1mg/mL)
• The antioxidant effect was dose-dependent and comparable to pharmaceutical antioxidant agents
• Provided the mechanistic basis for slippery elm’s traditional use in IBD — mucosal inflammation in Crohn’s and UC involves significant oxidative stress
• Concluded that slippery elm’s antioxidant properties justify its empirical use by IBD patients and warrant clinical trials

Hawrelak, J.A., & Myers, S.P. (2010). “Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study.” Journal of Alternative and Complementary Medicine, 16(10), 1065-1071.

• Pilot RCT of a formula containing slippery elm bark, lactulose, and oat bran for IBS
• Significant improvement in both constipation-predominant and diarrhea-predominant IBS symptoms
• Increased stool frequency in IBS-C, improved stool consistency in IBS-D
• Significant improvement in bloating and abdominal pain
• Proposed mechanism: prebiotic effects of slippery elm mucilage feeding beneficial bacteria and increasing butyrate production

Peterson, C.T., Sharma, V., Uchitel, S., et al. (2018). “Prebiotic potential of herbal medicines used in digestive health and disease.” Journal of Alternative and Complementary Medicine, 24(7), 656-665.

• In vitro fermentation study demonstrating that slippery elm polysaccharides significantly increase Bifidobacterium and Lactobacillus populations
• Increased SCFA production, particularly butyrate and propionate
• Established slippery elm as a prebiotic — not merely a physical demulcent but an active modifier of the gut microbiome

Historical and Clinical Context

Slippery elm suffers from a paucity of large-scale RCTs — a common problem for traditional herbs that cannot be patented. However, its 500+ years of continuous clinical use across Native American, Eclectic, and modern herbal traditions constitutes an enormous body of empirical evidence. The German Commission E and ESCOP (European Scientific Cooperative on Phytotherapy) recognize slippery elm as a demulcent with clinical applications in GI and respiratory mucosal inflammation.

Therapeutic Applications

Conditions

• Gastroesophageal reflux disease (GERD): Mucosal coating reduces acid contact with esophageal tissue
• Gastritis and peptic ulcer disease: Protective barrier over ulcerated mucosa
• Inflammatory bowel disease (Crohn’s and UC): Antioxidant, prebiotic, and mucosal protective effects
• Irritable bowel syndrome: Both IBS-C (bulk-forming) and IBS-D (soothing, reducing urgency)
• Leaky gut / intestinal hyperpermeability: Physical mucosal protection and stimulation of endogenous mucus
• Sore throat and pharyngitis: Demulcent coating of inflamed oropharyngeal mucosa (lozenges)
• Dry cough: Soothes irritated respiratory mucosa
• Interstitial cystitis: Demulcent protection of bladder mucosa (oral administration)
• Burns and wounds (topical): Poultice maintains moist wound environment
• Nutritive support during illness: Slippery elm gruel for patients who cannot tolerate solid food

Dosage Ranges

• Powdered bark (bulk): 1-2 tablespoons stirred into water, milk, or broth to form a gruel. 3-4 times daily.
• Capsules: 400-800mg, 3-4 times daily
• Lozenges: Dissolve in mouth as needed for sore throat (typically containing 100-200mg slippery elm per lozenge)
• Decoction: 4-16g of bark simmered (not boiled) in 500mL water for 10-15 minutes. Drink freely.
• Tincture: Generally less effective than powder or decoction because the mucilage is not well-extracted by alcohol. Glycerite preparations are preferable if a liquid form is needed.
• Poultice: Mix powdered bark with warm water to form a thick paste. Apply to affected area. Cover with gauze.

Forms

The powder mixed with water is the most effective form — it delivers the full mucilage content directly to the mucosal surface. Take 30 minutes before meals for GERD/gastritis (to coat the stomach before acid production increases with eating) or between meals for intestinal conditions. The powder can be mixed with cinnamon, honey, or banana to improve palatability. Lozenges are the most convenient form for sore throat. For intestinal conditions, capsules can substitute for powder but are less effective at delivering mucosal contact.

Safety & Contraindications

Exceptionally Well Tolerated

Slippery elm has one of the best safety profiles of any medicinal herb. It has been used as both food and medicine for centuries with no reports of toxicity. It is safe for children, the elderly, and debilitated patients. It was traditionally the first medicine given to the very sick — if a patient could tolerate nothing else, they could tolerate slippery elm gruel.

Contraindications

• None established. There are no known absolute contraindications to slippery elm.

Drug Interactions

• Absorption interference (theoretical): The thick mucilage may slow absorption of orally administered medications if taken simultaneously. Standard recommendation: separate slippery elm from pharmaceutical medications by 2 hours (take medications 1 hour before or 2 hours after slippery elm).
• No known pharmacokinetic or pharmacodynamic drug interactions.

Pregnancy and Lactation

Safe during pregnancy and lactation based on centuries of traditional use. Specifically used by Native American women during pregnancy for morning sickness and during labor. However, some sources caution about a theoretical abortifacient effect from the whole bark (as opposed to inner bark) — this concern is based on historical reports of the outer bark being used as an abortifacient, not the inner bark preparations used medicinally. Standard inner bark preparations are considered safe.

Side Effects

Minimal. Rare allergic reactions in individuals sensitive to the Ulmaceae family. The mucilage can cause a sensation of fullness. High doses may cause loose stools in some individuals due to the bulk-forming mucilage.

Sustainability Concerns

Slippery elm is classified as a species of conservation concern due to overharvesting and Dutch elm disease. Ethical herbalists should use sustainably harvested or cultivated bark and consider marshmallow root (Althaea officinalis) as a more sustainable alternative for many demulcent applications.

Energetics

TCM Classification (Modern Integration)

• Temperature: Neutral to slightly cool
• Flavor: Sweet, bland
• Meridian entry: Lung, Stomach, Large Intestine
• Actions: Nourishes Yin, moistens dryness, protects the mucosa, generates fluids
• TCM pattern correspondence: Stomach Yin deficiency (dry mouth, thirst, epigastric burning), Lung Yin deficiency (dry cough), Large Intestine dryness (dry constipation), any condition with damaged Yin fluids and mucosal inflammation

Ayurvedic Classification (Modern Integration)

• Rasa (taste): Madhura (sweet)
• Virya (energy/potency): Shita (cooling)
• Vipaka (post-digestive effect): Madhura (sweet)
• Dosha effects: Strongly pacifies Vata (moistening, grounding, nourishing). Pacifies Pitta (cooling, soothing). May increase Kapha in excess due to heavy, moist qualities.
• Dhatu affinity: Rasa (plasma), Mamsa (muscle — via mucosal tissue), Shukra (reproductive — via nourishing, building quality)
• Srotas affinity: Annavaha (digestive), Pranavaha (respiratory), Mutravaha (urinary)
• Guna (qualities): Guru (heavy), Snigdha (unctuous/oily), Mridu (soft) — the classic Vata-pacifying qualities

Functional Medicine Integration

Slippery elm is the foundational mucosal healing agent in functional medicine GI protocols. It addresses the physical integrity of the mucosal barrier — the front line of gut health.

Gut Restoration Protocol (“5R” Framework)

In the 5R gut restoration protocol (Remove, Replace, Reinoculate, Repair, Rebalance), slippery elm serves primarily in the Repair phase:

• Physical mucosal protection while the epithelium heals
• Stimulation of endogenous mucus production
• Prebiotic support for beneficial bacteria (bridges to the Reinoculate phase)
• Antioxidant protection of healing tissue

It is often combined with L-glutamine, zinc carnosine, deglycyrrhizinated licorice (DGL), and aloe vera in the Repair phase.

Intestinal Hyperpermeability (“Leaky Gut”) Protocol

Slippery elm’s mucilage provides an immediate physical barrier over the damaged epithelium, reducing the passage of inflammatory antigens through compromised tight junctions. While the underlying cause of hyperpermeability is addressed (food sensitivities, infections, stress, medications), slippery elm provides symptomatic relief and physical protection during healing.

GERD Protocol (Non-Pharmaceutical)

For patients seeking to taper PPIs (proton pump inhibitors), slippery elm provides mucosal protection during the transition. Combined with DGL, aloe vera gel, and dietary modifications, it addresses the mucosal vulnerability that drives reflux symptoms — treating the tissue rather than suppressing acid.

IBD Support Protocol

In Crohn’s disease and ulcerative colitis, slippery elm provides daily mucosal support between flares, reduces oxidative stress (Langmead 2002), feeds beneficial bacteria via prebiotic action, and provides gentle nutrition during flares when food intake is limited. It is not a substitute for disease-modifying therapy but an important complementary intervention.

Four Directions Connection

Primary Direction: Serpent (South — Physical Body)

Slippery elm is the quintessential Serpent medicine — it heals the body from the inside, at the most fundamental level of tissue integrity. The gut lining is where the outside world meets the inside of the body, where food becomes self, where the boundary between “me” and “not-me” is maintained. When this boundary is damaged (leaky gut, ulceration, inflammation), the Serpent’s domain is compromised. Slippery elm rebuilds this boundary with the simplest of materials — a soothing, protective gel that allows the body’s own intelligence to repair the damage. The Serpent does not overthink healing; it sheds, renews, and regenerates. Slippery elm facilitates this primal physical renewal.

Secondary Direction: Hummingbird (North — Ancestral Wisdom)

Slippery elm carries the deep medicine knowledge of the Native American peoples who first recognized its healing power. It is a Hummingbird medicine because it carries ancestral wisdom from one generation to the next — the Cherokee grandmother who taught the young mother to chew slippery elm bark during labor, the Meskwaki healer who fed slippery elm gruel to the sick child when nothing else would stay down. This is medicine that has been passed hand to hand through centuries. To use slippery elm is to participate in a chain of healing knowledge that stretches back to the original inhabitants of Turtle Island.

Tertiary: Jaguar (West — Emotional Healing)

The gut is where we hold our most primal fears and vulnerabilities. The phrase “gut feeling” points to the deep emotional intelligence of the viscera. When the gut is inflamed and permeable, we often feel emotionally raw and vulnerable as well. Slippery elm’s soothing, coating action on the gut provides a sense of safety and containment — the Jaguar’s teaching of creating a safe space in which to face our shadows. Slippery elm is the medicine you give to someone who feels “raw” — physically, emotionally, or both.

References

1. Langmead, L., Dawson, C., Hawkins, C., et al. (2002). Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study. Alimentary Pharmacology & Therapeutics, 16(2), 197-205.

2. Hawrelak, J.A., & Myers, S.P. (2010). Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. Journal of Alternative and Complementary Medicine, 16(10), 1065-1071.

3. Peterson, C.T., Sharma, V., Uchitel, S., et al. (2018). Prebiotic potential of herbal medicines used in digestive health and disease. Journal of Alternative and Complementary Medicine, 24(7), 656-665.

4. Felter, H.W., & Lloyd, J.U. (1898). Ulmus. In King’s American Dispensatory (18th edition). Ohio Valley Company.

5. Watts, C.R., & Rousseau, B. (2012). Slippery elm, its biochemistry, and use as a complementary and alternative treatment for laryngeal irritation. Journal of Investigational Biochemistry, 1(1), 17-23.

6. Deters, A.M., Lengsfeld, C., & Hensel, A. (2005). Oligo- and polysaccharides exhibit a structure-dependent bioactivity on human keratinocytes in vitro. Journal of Ethnopharmacology, 102(3), 391-399.

7. Moerman, D.E. (1998). Native American Ethnobotany. Timber Press, Portland, OR.

8. Mills, S., & Bone, K. (2005). Slippery elm bark. In The Essential Guide to Herbal Safety. Elsevier Churchill Livingstone.

9. Blumenthal, M., Goldberg, A., & Brinckmann, J. (2000). Slippery Elm Inner Bark. In Herbal Medicine: Expanded Commission E Monographs. Integrative Medicine Communications.

10. Bock, S. (2015). Integrative treatment of reflux and functional dyspepsia in children. Explore, 11(2), 116-124.