The therapeutic effectiveness of slippery elm has not been significantly investigated under clinical trial conditions, so evidence is derived from traditional, in vitro and animal studies.
It is widely accepted that the mucilage acts as a barrier against the damaging effects of stomach acid on the oesophagus and may also exert mild anti-inflammatory activity locally. Currently, clinical research is not available to determine the effectiveness of slippery elm in these conditions; however, anecdotally the treatment appears to be very successful and patients report rapid improvement in upper gastrointestinal symptoms.
Solid dose tablets and capsules are used in the treatment of diarrhea when it is believed the fibre will slow down gastric transit time and act as a bulking agent. Although clinical studies are not available to determine its effectiveness, the high mucilaginous content and presence of tannins in the herb provide a theoretical basis for its use.
DERMATITIS AND WOUNDS
Slippery elm has also been used as a topical agent to soothe irritated and/or inflamed skin conditions, wounds and burns and draw out boils and abscesses. When applied, it forms a protective gel-like layer, which is considered to have soothing properties.
Slippery elm: Other Uses
Clinical note – Essiac tea
Slippery elm is one of the key ingredients in Essiac tea, which was reportedly developed by the Ojibwa tribe of Canada and named after an Ontario nurse (Rene Caisse) to whom the formula for the herbal tea was given by an Ojibwa healer in 1922. It is used to treat a variety of diverse conditions such as allergies, hypertension, and osteoporosis. The tea is made up of a mixture of four herbs, Arctium lappa (burdock root), Rumex acetosella (sheep sorrel), Ulmus rubra (slippery elm) and Rheum officinale (rhubarb) and is considered to possess antioxidant and possibly anticancer activity. As a result, it is used widely by North American cancer patients during chemo- and radiotherapy for reduction in symptoms associated with cancer treatment and as a possible adjunctive treatment. In vitro tests with Essiac have identified anticancer activity, although its effects in vivo are controversial and evidence of efficacy is anecdotal. A recent study demonstrated that Essiac tea effectively scavenges several types of radicals and possesses DNA-protective effects.
Slippery elm: Dosage Range
Owing to insufficient data available from clinical studies, doses have been derived from Australian manufacturers’ recommendations.
• One to two capsules containing 150 mg of slippery elm before meals.
• Fluid extract (60%): 5 mL three times daily.
• Half a teaspoon of slippery elm bark powder is mixed with one cup of hot water and taken up to three times daily. For added flavouring, cinnamon or nutmeg can be added.
• Mix the coarse powdered bark with enough boiling water to make a paste and use as a poultice.