Yucca — a group of 30 species of shrub-like plants that grow mainly in dry regions of North America — is an ingredient in many dietary supplements that claim to promote joint health. Bark from the main stem (rhizome) of the Mohave yucca (Y. schidigera) is a common source of the yucca in these products.
Parts of various yucca plants have been used for centuries in traditional Native American medicine. But the only direct evidence that yucca relieves joint pain comes from a single study published in the 1970s and never validated in later publications.
Since then, scientists have isolated several yucca compounds that may turn out to have medicinal value. In the laboratory, some of these compounds display properties similar to those of anti-inflammatory drugs used to treat joint pain.
What these yucca-derived chemicals do in the test tube, however, is likely to be quite different from what they do in the human body. Scientific studies have validated many alternative and complementary therapies for arthritis, but yucca is not one of them.