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Slippery Elm Ulmus rubra Muhl.
Synonyms: Ulmus americana var. rubra (Muhl.) Aiton; U. fulva Michx; U. pendula
Other common names: Indian elm; moose elm; red elm; sweet elm
Drug name: Ulmi rubrae cortex
Botanical drug used: Inner bark
Indications/uses: Slippery elm bark is valued for its demulcent, emollient and
nutritive properties, as a food for people recovering from a disease. Traditionally,
it has been used to relieve the symptoms of indigestion, heartburn and atulence,
sore throats and coughs, to relieve inammation of the urinary tract, colic, irrita-
ble bowel syndrome (IBS) and to treat diarrhoea. An important medicinal plant
of Native Americans, a decoction of the bark was used as a laxative and to aid
delivery in childbirth.
Evidence: Scientic research on medicinal properties of slippery elm is lacking.
Safety: Safety data for slippery elm is lacking, so not recommended during
pregnancy and lactation and in children/ adolescents under 18years of age.
Main chemical compounds: Slippery elm inner bark is predominantly composed
of dietary bre including celluloses, lignin, mucilage and gums. The mucilage con-
sists of long-chain polysaccharides which combine with water to form a viscous,
semi-solid mass, and is regarded as the main active constituent. The polysaccha-
rides are composed of D-galactose, L-rhamnose and D-galacturonic acid and their
methylated derivatives and are highly branched. Other constituents include phytos-
terols, starch, minerals and oleic and palmitic acids (Pengelly and Bennett 2011).
No published clinical trials investigating slippery elm, other than in combination
with other herbs, have been carried out.
Phytopharmacy: An evidence-based guide to herbal medicinal products, First Edition.
Sarah E. Edwards, Inês da Costa Rocha, Elizabeth M. Williamson and Michael Heinrich.
© 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.
Slippery Elm 361
Irritable bowel syndrome: An open-label, uncontrolled pilot study assessed the
effects and tolerability of two herbal formulations containing slippery elm bark in 31
patients diagnosed with IBS. Of the two treatments, one signicantly improved both
bowel habit and IBS symptoms in the patients with constipation-predominant IBS.
The other treatment was not effective in improving bowel habit in individuals with
diarrhoea-predominating or alternating IBS, although it signicantly improved a
number of IBS symptoms (Hawrelak and Myers 2010). The constituents of the
formulae were diarrhoea-IBS formula: powdered bilberry fruit, slippery elm bark,
agrimony herb and cinnamon; constipation-IBS formula: slippery elm bark, lactu-
lose, oat bran and liquorice root.
Sore throat and pharyngitis: A multi-centre, randomised double-blind placebo-
controlled study was carried out to investigate a demulcent herbal tea formulation
(‘Throat Coat®’, containing 8.5% U. rubra powder) for the symptomatic treatment
of acute pharyngitis. Patients were given either Throat Coat (n=30) or placebo
(n=30). Throat Coat was found to be signicantly superior to placebo in providing
rapid, temporary relief from sore throat pain in patients with pharyngitis (Brinck-
mann et al. 2003). As with the IBS study, it is not possible to attribute any perceived
benets of the treatment to a particular ingredient in the formulation.
Pre-clinical evidence and mechanisms of action:
Few studies on slippery elm have been reported.
Antioxidant activity in inflammatory bowel disease: An in vitro study investigated
the antioxidant effects (in cell-free oxidant-generating systems and inamed human
colorectal biopsies) of six herbal therapies used to treat inammatory bowel dis-
ease (IBD). Slippery elm, like the positive control 5-aminosalicylate (and most of
the other herbal remedies tested), was found to have a dose-dependent antioxidant
effect and was the most potent of the herbs tested in the 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 inammatory conditions
(Langmead et al. 2002). In another in vitro study, 28 herbs were screened for peroxy-
nitrite scavenging activity. Slippery elm ranked fth out of the 28 herbs, after witch
hazel bark, rosemary, jasmine tea and sage (Choi et al. 2002).
Interactions: No case reports of interactions are available. However, the mucilage
present in slippery elm may reduce absorption of medicines if taken concomitantly
and it has been suggested that other medicines should be taken 1hour prior to, or
several hours after, slippery elm preparations (Gardner and McGufn 2013).
Contraindications: Not recommended during pregnancy and lactation, in children
and adolescents under 18 years of age, or in patients with liver disease, gallstones
and other biliary disorders, due to lack of safety data. (MHRA 2013).
Adverse effects: No reports of side effects have been identied (Gardner and
Dosage: As a food during recovery from an illness, slippery elm is made into a
thin porridge or gruel. For manufactured herbal products follow manufacturers’
dosage recommendations. No recommended dosage is available due to lack of sci-
General plant information: U. rubra is endemic to North America and cultivated
there and in the British Isles (Morton 1990). In the United Kingdom, slippery elm
bark can only be sold in premises which are registered pharmacies, under the super-
vision of a pharmacist. U. rubra, like other elms, is susceptible to Dutch elm disease,
so larger trees are becoming increasingly rare, resulting in harvesters using greater
quantities of smaller trees to obtain the same quantities of bark with consequent
conservation issues (Pengelly and Bennett 2011).
Brinckmann J, Sigwart H, van Houten Taylor L. (2003) Safety and efcacy of a tra-
ditional herbal medicine (Throat Coat) in symptomatic temporary relief of pain in
patients with acute pharyngitis: a multicenter, prospective, randomized, double-blinded,
placebo-controlled study. Journal of Alternative and Complementary Medicine 9(2):
Choi HR, Choi JS, Han YN, Base SJ, Chung HY. (2002) Peroxynitrate scavenging activity of
herb extracts. Phytotherapy Research 16(4): 364–367.
Gardner Z, McGufn M. (Eds.) (2013) American Herbal Product Association’s Botanical
nd Edition. CRC Press, USA, 1072 pp.
Hawrelak JA, Myers SP. (2010) Effects of two natural medicine formulationson irritable bowel
syndrome symptoms: a pilot study. Journal of Alternative and Complementary Medicine
16(10): 1065– 1071.
Langmead L, Dawson C, Hawkins C, Banna N, Loos S, Rampton DS. (2002) Antioxidant
effects of herbal therapies used by patients with inammatory bowel disease: an in vitro
study. Alimentary Pharmacology and Therapeutics 16(2): 197–205.
MHRA. (2013) Summary of product characteristics, Potter’s Slippery Elm Indigestion Relief.
(accessed January 2014).
Morton JF. (1990) Mucilaginous plants and their uses in medicine. Journal of Ethnopharma-
cology 29(3): 245– 266.
Pengelly A, Bennett K. (2011) Appalachian plant monographs: Ulmus rubra Muhl., Slip-
pery Elm. http://www.frostburg.edu/fsu/assets/File/ACES/ulmus%20rubra%20-nal.pdf
(accessed 3 January 2014).