Overview of Slippery Elm Bark and It's Medical Significance

Slippery elm with a cup of water

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In the herbal world, slippery elm is the inner bark of a particular species of the elm tree. It is used for a number of herbal preparations, many of which relieve throat and digestive issues. The light, fluffy bark is commonly used as a binder for making herbal pills and as a light non-stick coating to keep homemade lozenges from sticking together.

What Slippery Elm Is

The slippery elm tree is very similar to the more common American elm.

  • Its branches grow higher, and there are fewer large branches.
  • Its leaves are the signature elm shape — broad, elliptical, and serrated — though they are larger with more of a sandpaper-like texture than other elms.
  • When cut, the slippery elm also has more of a reddish inner wood in the heart of the trunk.

Slippery elm trees are found throughout the eastern and central United States, and it is a native to North America. It often grows in drier soils than the American elm and is most plentiful and best-known for its medicinal harvests in the Appalachian mountains.

Like the American elm, the slippery elm is also prone to Dutch elm disease, but it is slightly more resistant. This has caused much controversy over the bark harvest and is why it's often not advised to harvest it yourself.​

  • Latin name: Ulmus fulva or Ulmus rubra
  • Common name: slippery elm, soft elm, red elm
  • USDA Hardiness Zone: Most commonly found in Zone 3-9
  • Exposure: Sun to partial shade. More tolerant of shade than many deciduous trees.

How Slippery Elm Is Harvested

The useful properties of the slippery elm come from the inner bark. It has a slick, mucilage (a glue-like quality) which has long been used by Native Americans for its medicinal benefits.

To harvest slippery elm, the bark of the tree is removed. Then, the inner bark is separated from the outer bark. This is best done in spring through early summer when the sap is flowing.

However, it is not advised that you head out to the woods to harvest your slippery elm. You may run into issues with Dutch elm disease, conservation lands that are protected, and you may further impact the health of a vulnerable species of tree.

For years, slippery elm trees have been harvested by cutting down entire trees. This is not ideal, particularly given the elm population's problems with disease and overharvesting.

Most professional wildcrafters who harvest slippery elm for herbal companies will use sustainable practices to ensure the long life of the species. These often include leaving enough bark on each tree to protect it from harm. They will also leave a tree for a few years until the bark has regrown before harvesting again.

Rather than harvest your slippery elm, consider purchasing it from a reliable herb supplier. Better yet, find one that uses eco-friendly and sustainable harvesting methods. Given the potential environmental impact, already processed slippery elm is relatively inexpensive.

Uses for Slippery Elm

Slippery elm bark is a highly nutritive food. The soft inner bark can be fed as a healing food to anyone suffering from an illness. It is easily digestible and typically fed in porridge or mixed with oatmeal.

Slippery elm's mucilage properties make it effective for soothing irritated mucous membranes and the digestive tract. Slippery elm tea, lozenges, and supplements are often considered an alternative, natural treatment for IBS and heartburn. Consult your physician before using it as it can counteract other medications.

Slippery Elm is useful as a binder for making pills, boluses, and as a natural dusting powder to keep your herbal drops from sticking together. It is also used in a gentle body powder, in salves, and lip balms and other skin-soothing balms.