Health Benefits of Slippery Elm

Folk Remedy Believed to Treat Sore Throat and IBS

slippery elm bark
Slippery elm bark. Steve Gorton/Dorling Kindersley/Getty Images

Slippery elm (Ulmus rubra) is a type of elm tree native to eastern North America from southern Quebec to northern Florida and east to Texas. The inner bark has long been used in traditional Native American medicine to treat wounds and gastrointestinal ailments. Slippery elm is also a main ingredient in essiac tea.

Slippery elm contains a type of soluble fiber known as mucilage. Mucilage traps and absorbs water, forming a gel-like substance that can coat mucous membranes, providing short-term relief of pain and inflammation The high calcium content may also act as a mild antacid.

Slippery elm is also known as red elm, gray elm, soft elm, moose elm, and Indian elm. It should not be confused the American elm (U. americana), the species of which it resembles but has no medicinal properties.

Health Benefits

Slippery elm has long been used in folk medicine. It is either taken orally or applied topically to aid in the healing of cuts and burns. Among some of the conditions slippery elm is believed to treat are:

Some proponents claim that slippery elm can treat upper respiratory tract infections, syphilis, herpes, gout, psoriasis, and even breast or lung cancer. To date, there is no clinical evidence to support these claims.

Weight Loss

There are some who insist that slippery elm can promote weight loss by suppressing the appetite and "detoxing" the bowel. The presumption is that the production of mucilage can increase the volume of your stomach contents, filling you up faster. The mucilaginous bulk is then believed to "trap" dietary fats and speed bowel clearance. The hypothesis is yet to be proven.

A 2018 study in the Journal of Dietary Supplements found that women provided a four-week course of a slippery elm supplement experienced no differences in body composition or waist size compared to those given a placebo.

Despite this, there are some who consume slippery elm powder as a porridge-like gruel to "amplify" these effects. Not only is there no evidence that this works, but it is also unknown how safe the practice is.

Sore Throat

Slippery elm has been used to make commercial medicines as far back as the 1840s when a physician named Henry Thacker starting producing herbal remedies for sale to doctors. Among them was a slippery elm elixir that was first sold as an oral suspension and later as lozenges. As a natural demulcent, slippery elm can reduce inflammation by coating lining of the throat and esophagus.

Thacker's Slippery Elm Lozenges are still produced today, in addition to a slippery elm lip balm used to treat chapped lips. Other manufacturers have since joined in, producing slippery extracts, tinctures, lotions, and herbal teas.

In the 1960s, the U.S. Food and Drug Administration classified slippery elm as a botanical drug, believing it safe for the treatment of minor sore throat pain.

However, the agency fell short of declaring it effective, characterizing slippery elm as "a demulcent with limited clinical effects."

While slippery elm is believed by some to relieve the symptoms of acid reflux, the drug action is relatively short-lasting (around 30 minutes) and does nothing to treat the underlying causes of reflux.

Digestive Disorders

Proponents of slippery elm claim that it can alleviate many of the symptoms of inflammatory bowel diseases (such as ulcerative colitis) by forming a temporary protective barrier in the intestines. To date, the evidence of this is mixed.

A 2002 study from England found that slippery elm exerted antioxidant effects on colon tissue samples taken from people with ulcerative colitis. What the test tube study did not show is whether the same effect would occur if a slippery elm was taken orally.

Meanwhile, other scientists have looked into whether slippery elm can control the symptoms of irritable bowel syndrome (IBS), classified either as constipation-predominant IBS (IBS-C) or diarrhea-predominant IBS (IBS-D).

A 2008 study from Australia reported that two different herbal supplements containing slippery elm were able to increase bowel frequency by 20 percent in people with IBS-C but had minimal effect in people with IBS-D.

Both groups were also said to experience improvements is straining, abdominal pain, and bloating. Despite the positive findings, the conclusions were limited by the fact that the research was conducted by a commercial herbal drug manufacturer.

Possible Side Effects

Due to the sparsity of research, little is known about the safety of slippery elm. Side effects commonly cited include nausea and skin irritation. Some people may also experience allergy, usually those who are allergic to elm pollen or have a cross-reactive allergy to peach.

Because slippery elm can coat the digestive tract, it may interfere with the absorption of certain drugs. To avoid this, separate the doses of slippery elm and your other drugs by at least two hours. When you do take your regular medications, drink plenty of water unless otherwise indicated.

The outer bark of the slippery elm tree has long been used in folk medicine to induce abortion. Although there is little evidence that this actually works, women who are pregnant or intend to get pregnant should avoid slippery elm just to be safe.

Dosage and Preparation

There are no guidelines for the appropriate use of slippery elm. While slippery elm is considered safe when used for the short-term treatment of sore throat, you shouldn't assume that is can be used with impunity. As a general rule, never exceed the recommended dose on the product label.

Slippery elm remedies are typically made from the powdered inner bark of the tree. The powder is then used to manufacture supplements in capsule form or to create extracts for use in tinctures, lozenges, salves, and lip balms. Slippery elm powder can also be purchased in bulk or packaged in tea bags.

What to Look For

Dietary supplements are not stringently regulated in the United States and do not need to undergo rigorous testing or research before reaching the market shelves. Because of this, the quality of supplements can vary considerably from one brand to the next.

To better ensure quality and safety, only purchase supplements from manufacturers with an established brand presence. While vitamin manufacturers will often voluntarily submit their products for testing by an independent certifying body (like the U.S. Pharmacopeia or ConsumerLab), herbal supplements manufacturers rarely do.

Use your best judgment when buying a slippery elm supplement and try not to be swayed by health claims that may or may not be true.

Other Questions

Is slippery elm an endangered species?

Slippery elm is not yet an endangered species, but there are grave fears about its sustainability. Their preferred habitat, the floodplains, have been aggressively targeted for urban development and channel construction. Because the timber is not of much commercial use, little effort has been made to replant the trees.

Moreover, due to the onslaught to Dutch Elm Disease, there are very few mature slippery elm trees left in nature. 

The slippery elm is currently on the "special concern" list in Rhode Island and is already believed to be eradicated from Maine. Environmentalists urge against the use of wild-harvested bark to prevent the total loss of this ancient species.

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