yucca

Botanical names
Yucca schidigera, Yucca spp.
Parts used and where grown
This desert tree grows primarily in the southwestern United States and is related to the Joshua tree. The stalk and root are both used in herbal medicine.
Yucca has been used in connection with the following conditions (refer to the individual health concern for complete information):
Science Ratings - Health Concerns
* - Osteoarthritis
* - Rheumatoid arthritis
*** - Reliable and relatively consistent scientific data showing a substantial health benefit.
** - Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
* - For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.
Historical or traditional use (may or may not be supported by scientific studies)
Native Americans used the soapy leaves from yucca for numerous conditions. Poultices or baths were used for skin sores and other diseases as well as for
sprains. Inflammation of all sorts, including joint inflammations and bleeding, were also treated with yucca. It is also reported that Native Americans washed their hair with yucca to fight dandruff and hair loss.
Active constituents
The saponins from yucca are the major constituents in the plant. They have both a water- and fat-soluble end and therefore act like soap. One preliminary trial reportedly found benefit for patients with
osteoarthritis and rheumatoid arthritis.1 The authors of the study speculate that yucca saponins may block release of toxins from the intestines that inhibit normal formation of cartilage. This has yet to be proven in human pharmacological studies. An extract of one species of yucca has been found to fight melanoma cells in test tube studies.2 Clinical trials are lacking to prove whether yucca may be useful for treating cancer in humans.
How much is usually taken?
Although the exact dosage of yucca for arthritis is unclear, some sources suggest up to 2 grams of yucca root in capsules per day.3 Alternatively, 1/4 ounce (7 grams) of the root can be boiled in a pint (500 ml) of water for 15 minutes. Three to five (750–1250) cups of this tea may be taken each day.4

Are there any side effects or interactions?
Yucca can cause loose stools at higher amounts (several times higher than the recommended amounts).5 Yucca and other saponins can cause red blood cells to burst (known as “hemolysis”) in test tubes. The level to which this occurs when the saponins are taken by mouth, if it occurs at all, is unknown. However, yucca is approved for use in foods as a foaming agent (particularly in root beer). Since there have been no reports of problems with hemolysis in root beer drinkers, yucca herbal supplements are believed to be generally safe.6 Use of yucca for more than three months consecutively is not recommended as it may interfere with the absorption of fat-soluble vitamins.7
At the time of writing, there were no well-known drug interactions with yucca.