Slippery Elm

Abstract

This chapter presents clinical evidence, pre-clinical evidence and mechanisms of action, interactions, contraindications, information about adverse effects and dosage of Slippery Elm (Ulmus rubra). 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 flatulence, sore throats and coughs, to relieve inflammation of the urinary tract, colic, irritable 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. Slippery elm inner bark is predominantly composed of dietary fibre including celluloses, lignin, mucilage and gums. U. rubra is endemic to North America and cultivated there and in the British Isles.

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THR
Slippery Elm Ulmus rubra Muhl.
Synonyms: Ulmus americana var. rubra (Muhl.) Aiton; U. fulva Michx; U. pendula
Willd.
Family: Ulmaceae
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 inammation 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: Scientic 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).
Clinical evidence:
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 signicantly 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 signicantly 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 signicantly 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
benets 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 inamed human
colorectal biopsies) of six herbal therapies used to treat inammatory 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 inammatory 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 McGufn 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 identied (Gardner and
McGufn 2013).
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-
entic data.
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

362 Phytopharmacy
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).
References
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placebo-controlled study. Journal of Alternative and Complementary Medicine 9(2):
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Choi HR, Choi JS, Han YN, Base SJ, Chung HY. (2002) Peroxynitrate scavenging activity of
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Gardner Z, McGufn M. (Eds.) (2013) American Herbal Product Association’s Botanical
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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
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study. Alimentary Pharmacology and Therapeutics 16(2): 197–205.
MHRA. (2013) Summary of product characteristics, Potter’s Slippery Elm Indigestion Relief.
http://www.mhra.gov.uk/home/groups/spcpil/documents/spcpil/con1376454722191.pdf
(accessed January 2014).
Morton JF. (1990) Mucilaginous plants and their uses in medicine. Journal of Ethnopharma-
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pery Elm. http://www.frostburg.edu/fsu/assets/File/ACES/ulmus%20rubra%20-nal.pdf
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