Ask Horse Journal: 08/05

Safety of Devil’s Claw and Yucca
I am questioning the dangers of devil’s claw and yucca in terms of gastric ulcers. I had fed some horses that sort of supplement at their owners’ request, only to find that the horses became picky eaters after a couple months on the supplements and refused to eat grain with the liquid supplements. Did you check on long-term-health issues’

Horse Journal Response:

There’s lots of incorrect herbal information out there.??Devil’s claw does reduce inflammation, by a variety of mechanisms. However, devil’s claw doesn’t contain steroid-like substances.??

In Western herbal circles, devil’s claw is classified as a “bitter,” and this is why it’s felt to be contraindicated with stomach ulcers.?? There are no studies looking at its effect on acid secretion or as a stomach irritant, though.??

In a large German trial of devil’s claw for arthritis and back pain, two of 75 participants were classified as possible adverse reactions, one with indigestion-type complaints and the other a feeling of fullness.??Because of its pharmacology, actions similar to NSAIDs, there’s at least a theoretical potential for gastric irritation, but in our experience it’s much less than with the drugs.??

However, studies have shown that devil’s claw extracts stimulate?? contraction of smooth muscle in the gastrointestinal tract, and this is felt to be the reason for intestinal discomfort, not because they produce ulcers. These studies have been on isolated sections of intestine under laboratory conditions, not in live people or animals.?? We’ve had many horses on devil’s claw, including in high dosages, for six months to two years with no ill effects on appetite or signs of abdominal pain.

As for yucca, it’s true that there are steroid-like compounds (saponins), but new research shows direct anti-inflammatory effects from a new isolated component in yucca called yuccaol, and yucca has been found to contain a potent plant antioxidant. As for yucca causing ulcers, there’s nothing to support that idea.??

The only reports of adverse effect of yucca are in studies that fed concentrates of the saponins to rats in high amounts, equivalent to 100 grams/day of purified saponins for an average-size horse, or 1,000 grams of actual yucca.??

Inhibition of urea cycle enzymes and insulin resistance were produced at those dosages, but this isn’t even remotely close to typical supplement dosages. We don’t know why the horses decided to start refusing the supplement, but it’s highly unlikely it was because they developed ulcers.

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