Slippery Elm: The Soothing Solution for Sore Throats
Ulmus rubra
Ancient Use
Slippery elm (Ulmus rubra) is a tree native to the Eastern and Central United States and Canada. Native Americans traditionally used its inner bark, peeled from twigs and branches, for a variety of medicinal and practical purposes. The inner bark is naturally sweet and fibrous and was chewed to quench thirst or brewed into a decoction to soothe the stomach, aid digestion, relieve sore throats, and calm coughs. Additionally, it was used as a mild laxative. Beyond its medicinal applications, Native Americans also incorporated slippery elm bark into craftwork for making floor matting, baskets, and fishing nets, and even utilized it in the construction of canoes and horse saddles.
Relevant Pathophysiology
Since the COVID-19 pandemic, you have likely experienced at least one sore throat or upper respiratory infection (URI). When viruses such as COVID-19 or influenza infect the upper airways, they trigger an inflammatory response in the throat (pharynx). While inflammation helps the body fight off pathogens, it also leads to irritation of the mucous membranes. Postnasal drip occurs when mucus from the nasal cavity slides down into the laryngopharynx. This further exacerbates throat irritation, causing swelling, discomfort, and coughing.
Despite the common occurrence of sore throats, effective treatment options remain limited. Over-the-counter lozenges provide only temporary numbing relief, and in severe cases, corticosteroids like prednisone are prescribed. However, steroids carry risks and should not be used frequently. Historically, many cultures, including Native Americans, relied on herbal teas to relieve sore throats. This article explores how slippery elm’s unique properties make it a powerful natural remedy for throat irritation.
Major Phytochemicals
1. Mucilage: The Key Soothing Agent
One of the most significant medicinal components of slippery elm is mucilage—a carbohydrate-based compound that forms a thick, sticky gel when mixed with water. When consumed in tea, mucilage coats and adheres to the mucosal surfaces of the throat, providing a soothing effect. This gel-like coating helps alleviate dryness and irritation, reducing the urge to cough.
Mucilage closely resembles the body’s natural mucus, which is rich in mucins—carbohydrate molecules that protect and lubricate mucous membranes. This similarity enhances slippery elm’s ability to relieve sore throat symptoms and support the body’s natural defenses. Additionally, mucilage increases the bioavailability of other key phytochemicals in slippery elm, including tannins and salicylic acid.
2. Tannins: Astringent and Antimicrobial Properties
Tannins are water-soluble phenolic compounds known for their astringent properties, which help constrict mucous membranes and reduce excess mucus production. They also have antimicrobial effects by promoting tissue contraction and expediting healing.
Furthermore, tannins are potent antioxidants, neutralizing free radicals generated by inflammation during respiratory infections. This antioxidant action protects throat tissues from further damage. The combined effects of mucilage and tannins—soothing, antimicrobial, and anti-inflammatory—make slippery elm an effective sore throat remedy.
3. Salicylic Acid: Natural Anti-Inflammatory Agent
Slippery elm also contains salicylic acid, the active compound from which aspirin was derived. Salicylic acid enhances the anti-inflammatory effects of slippery elm, further reducing throat irritation and discomfort (1).
Scientific Evidence
Although human studies on slippery elm for sore throat relief are limited, one randomized controlled trial supports its traditional use. In this study, participants were given either warm tea containing slippery elm or a control tea (decaffeinated Lipton’s orange pekoe tea). At 1, 5, and 10 minutes post-consumption, participants rated their throat sensations. At each time point, those in the slippery elm group reported significantly greater soothing effects than those in the control group (1).
Other sources have highlighted slippery elms use in aiding singers to relieve dry or sore throats (2) and to aid in management of acid reflux symptoms (3).
Slippery elm is widely regarded as safe and is not associated with significant liver toxicity (4).
Potential Gastrointestinal Benefits
While slippery elm is most commonly used for sore throats, its benefits extend to gastrointestinal health. Given its historical use by Native Americans for digestive ailments, its ability to coat and soothe the digestive tract makes theoretical sense.
1. Anti-Inflammatory Effects in the Gut
In-vitro studies show that slippery elm reduces free radicals in inflamed human colon biopsies, suggesting a potential role in treating inflammatory bowel diseases (5).
2. Improved Gut Function in IBS Patients
A study conducted in Australia examined the effects of a herbal formula containing slippery elm, aloe vera, guar gum, pectin, peppermint oil, and glutamine. Participants with irritable bowel syndrome (IBS) reported significant improvements in indigestion, heartburn, nausea, constipation, diarrhea, and abdominal pain. Additionally, the formula positively affected gut microbiome composition. Some participants were even able to discontinue proton pump inhibitors by the end of the study (6).
These findings suggest that slippery elm’s mucilage and anti-inflammatory tannins may provide relief not only for sore throats but also for gastrointestinal disorders.
Personal Experience
Since completing my medical residency in 2019 and working as a hospitalist, I have treated hundreds of patients with upper respiratory infections, including COVID-19, influenza, and RSV. Having personally experienced sore throats from repeated exposures to URIs, I understand how frustrating they can be.
In 2020, I discovered slippery elm tea and was immediately impressed by its soothing effect. After my first cup, I noticed instant relief from throat irritation and coughing. Since then, I have recommended slippery elm tea to countless patients, friends, and family members as a safe and effective sore throat remedy. Given the ongoing waves of respiratory infections, I strongly suggest keeping a supply of slippery elm tea on hand.
Future Research
Despite its long history of use and promising biochemical mechanisms, research on slippery elm remains limited. Given its potential as a safe, inexpensive, and effective sore throat remedy, larger randomized controlled trials are needed to validate its benefits. Additionally, its potential role in gastrointestinal health, particularly in conditions like inflammatory bowel disease and IBS, warrants further investigation.
The wisdom of Native Americans, who recognized slippery elm’s medicinal properties centuries ago, will likely be confirmed by modern research. Try a cup of warm slippery elm tea the next time you have a sore throat and see for yourself! With continued scientific exploration, slippery elm may become a widely recognized natural remedy for both respiratory and digestive health.
References:
Watts, Christopher & Rousseau, Bernard. (2012). Slippery Elm, its Biochemistry, and use as a Complementary and Alternative Treatment for Laryngeal Irritation. Journal of Investigational Biochemistry. 1. 17-23. 10.5455/jib.20120417052415.
Boon, H., & Smith, M. The complete natural medicine guide to the 50 most common medicinal herbs. RobertRose, Toronto, 2004.
Vemulapalli, R. Diet and lifestyle modifications in the management of gastroesophageal reflux disease. NutrClinPract 2008; 23: 293-298
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Slippery Elm. [Updated 2024 Jan 5]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK599741/
Langmead L, Dawson C, Hawkins C, Banna N, Loo S, Rampton DS. Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study. Aliment Pharmacol Ther. 2002 Feb;16(2):197-205. doi: 10.1046/j.1365-2036.2002.01157.x. PMID: 11860402.
Ried K, Travica N, Dorairaj R, Sali A. Herbal formula improves upper and lower gastrointestinal symptoms and gut health in Australian adults with digestive disorders. Nutr Res. 2020 Apr;76:37-51. doi: 10.1016/j.nutres.2020.02.008. Epub 2020 Feb 8. PMID: 32151878.
Images:https://open.ocolearnok.org/medicalterminology/chapter/respiratory-system/; https://www.flickr.com/photos/natureserve/13412555744; https://commons.wikimedia.org/wiki/File:Ulmus_rubra_8zz.jpg; https://commons.m.wikimedia.org/wiki/File:Ulmus_rubra_15-p.bot-ulmu.rubra-16.jpg
