The yucca plant is native to the high deserts of the southwestern United States and Mexico. It is also found less commonly in parts of the eastern United States and West Indies. Extracts from the plant's root are used in alternative medicine as a soap and as an herbal dietary supplement. The yucca has at least 40 species, including Yucca filamentosa, the most common type, Yucca brevifolia (Joshua tree), Yucca aloifolia (Spanish bayonet), and Yucca gloriosa (Spanish dagger). Two other species, Yucca baccata and Yucca glauca, are called soap plant because their roots are especially good for making soap.
Yucca plants are tree-like succulents of the lily family (Liliaceae) with stemless stiff, pointed leaves that end in a sharp needle. The Joshua tree, the namesake of Joshua Tree National Park near Palm Springs, California, is believed to have been named by Mormon settlers because the plant's angular branches resembled the outstretched arms of Joshua leading them out of the desert. The yucca flower is a series of white or purple blossoms on a long stalk.
Native American tribes in the southwestern United States and Northern Mexico found numerous uses for the yucca, dating back hundreds of years. Several tribes, including the Western Apaches on the Fort Apache Reservation in Arizona, use the plant today. The most common use seems to be for hygiene. Roots of the yucca baccata are pounded to remove extracts that are made into shampoo and soap. The Apaches also use yucca leaf fibers to make dental floss and rope. Historically, Western Apaches mixed ground juniper berries with yucca fruit to make a gravy. They also made a fermented drink from juniper berries and yucca fruit pounded to a pulp and soaked in water. Other Native American groups used yucca soap to treat dandruff and hair loss.
Native Americans also used yucca plants for a variety of other non-medical purposes, including making sandals, belts, cloth, baskets, cords, and mats. Such uses can still be found today among Hopi, Papago, and Ute Indians. The Zuni used a mixture of soap made from yucca sap and ground aster to wash newborn babies to stimulate hair growth. Navajos would tie a bunch of yucca fibers together and use it as a brush for cleaning metates.
The primary medical use of yucca is to treat arthritis and joint pain and inflammation. Native Americans used sap from the leaves in poultices or baths to treat skin lesions, sprains, inflammation, and bleeding. Teas made from yucca mixed together with other herbs are still brewed by folk healers in northern New Mexico to treat asthma and headaches. Constituents of the yucca are used today to treat people with osteoarthritis and rheumatoid arthritis. The plant's medical properties are found in saponins, precursors of cortisone, which prevent the release of toxins from the intestines that restrict normal cartilage formation. Saponins are produced naturally in the body by the adrenal glands. It is believed yucca works best for arthritis when taken over an extended period of time.
Yucca extract is used to treat a variety of other conditions, including migraine headaches, colitis, ulcers, wounds, gout, bursitis, hypertension (high blood pressure), and high LDL cholesterol (also called bad cholesterol). Liver, kidney, and gallbladder disorders are also treated with yucca extract. More recently, researchers have found that resveratrol, a compound found in yucca extract as well as in red wine, inhibits the aggregation or clumping of blood platelets. This finding suggests that yucca extract may be useful in preventing blood clots.
A number of commercial uses for yucca extract have been found, including adding it to root beer, alcoholic beer, and cocktail mixers as a foaming agent. The bittersweet dark brown extract is also used as an additive in ice cream and other foods.
The extract of the Yucca schidigera (Mojave or Mo-have yucca) is also used as an additive in natural pet foods. It is reported to speed up bowel elimination, reduce fecal and urine odor, and improve digestion in dogs and cats. It can also be added to pet food as a spray or drops. Several studies also show that when added to animal feed, Yucca schidigera extract can reduce noxious ammonia
gas in the waste products of poultry, pigs, cows, and horses. A decrease in ammonia levels can increase egg production in chickens and milk production in dairy cattle.
The standard dosage of concentrated yucca saponins is two to four tablets or capsules a day. Yucca concentrate is also available as a tea, with the usual dosage being 3–5 cups a day. Capsules and tablets are commonly sold in doses of 500 milligrams. A bottle of 30, 60, 90, or 100 units costs $6–10 and can usually be found in health food stores.
Since yucca has rarely been studied in a scientific setting, it is not known whether it is safe in children, pregnant or lactating women, or people with a history of severe kidney or liver diseases, heart disease, or cancer. It appears to be nontoxic to other mammals, including such household pets as cats and dogs.
Saponins extracted from yucca plants are generally considered safe when used in traditional doses and forms based on several hundred years of use by Native Americans, both as food and medicine. In recent years, the only reported minor problems are rare cases of diarrhea and nausea. Some people who are sensitive to plant allergens may develop a mild skin rash from contact with yucca sap.
Long-term internal use of yucca extract may interfere with the absorption of such fat-soluble vitamins as A, D, E, and K. As of 2002, however, no interactions between yucca and standard prescription medications have been reported.
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Ken R. Wells
Rebecca J. Frey, PhD