Slippery elm is among several species of elm native to eastern North America. It is closely related to the East Asian dwarf elm (U. pumila L.), which has been introduced to the United States through cultivation, and often hybridizes with it. In the last century, many native populations of North American elms, as well as trees planted in urban areas, were devastated by the introduced Dutch elm disease. Ulmus rubra is susceptible to this disease; hybrids with U. pumila are less susceptible and are sometimes planted for that reason. The wood is sometimes used, although it is considered to be of only moderate quality and the tree does not grow very large. The inner bark is very mucilaginous when moistened; it is used in herbal medicine particularly for irritation or inflammation of the throat or digestive system, and occasionally for psoriasis. It has also been considered to be a tonic food, and was formerly known as a survival food, to be eaten in times of famine.

Slippery elm has received almost no scientific study, despite its longstanding popularity. However, the soothing effects of mucilaginous products are well documented by human experience. Several in vitro studies have shown that slippery elm has antioxidant properties. Slippery elm is included in the Essiac ?anti-cancer? herbal formula, which has been used for decades despite a near-total lack of evidence that it has any specific activity against cancer; in vitro studies are few and unimpressive, and it appears that not a single live animal study has ever been published, although animal studies do not require FDA permission. While the formula is probably harmless, therefore, it is quite unlikely to be of much value. (Individual cases of remission associated with use have been documented, but without some kind of study there is no reason to believe that these represent any increase over the usual small number of spontaneous cures.)

Selected References

Langmead, L., C. Dawson, C. Hawkins, N. Banna, S. Loo, and D. S. Rampton. 2002. Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study. Aliment. Pharmacol. Ther. 16:197-205.

Lester, D. T., and E. B. Smalley. 1972. Response of backcross hybrids and three-species combinations of Ulmus pumila, U. japonica and U. rubra to inoculation with Ceratocystis ulmi. Phytopathology 62:845-848.

Santamour, F. S. 1971. A triploid Elm (Ulmus pumila X U. rubra) and its aneuploid progeny. Bull. Torrey Bot. Club 98:310-314.

Sherman-Broyles, S. L. 1997. Ulmus. Pp. 369-375 in: Flora of North America Editorial Committee, eds., Flora of North America, vol. 3. Oxford University Press: New York.

Wiegrefe, S. J. 1994. Phylogeny of elms (Ulmus, Ulmaceae): Molecular evidence for a sectional classification. Syst. Bot. 19:590-612.