Yucca - Medicinal Uses, Interactions, Side Effects, Dosage

This article provides description about yucca, its uses and benefits, some of its main interactions and side effects. This article also deals with the preparations, dosage, clinical trials and phamocology for yucca.

Yucca

Yucca plants include a number of different trees and shrubs found in arid portions of North and Central America. Common species include Yucca aloifolia (Spanish bayonet), Y. brevifolia (Joshua tree), Y. filamentosa (Adam's needle),Y. glauca (soap­weed), and many others. All parts of the plant, as well as many different species, are used.

Uses and Benefits:

As a dietary supplement in the U.S., yucca is commonly marketed as an anti-inflammatory herb, primarily for the treatment of arthritis symptoms. There are also claims that yucca may help reduce blood pressure and cholesterol levels. Traditionally, yucca has been used by different cultures for a wide variety of medical conditions, including gout, gall bladder problems, diabetes, genitourinary disorders, indigestion, and constipation, and also has been used as a diuretic and topically for inflammation or general skin cleansing. Native Americans have created soap, shampoo, rope, and textiles from yucca plants. Plant constituents are also used commercially as foaming agents and flavorings.

Pharmacology:

Yucca plants contain steroidal saponins such as sarsasapogenin and tigogenin. Saponins are widely used for their detergent and foaming properties, and have also been stud­ied in animals for their potential anticholesterol, anti-inflammatory, and anticarcinogenic activities. Yucca leaf protein can interfere in vitro with the protein synthesis of cells infected by herpes simplex virus and cytomegalovirus. Flowers of certain yucca species contain polysaccharides with tumor-inhibiting effects in mice.

Clinical Trials:

Yucca has been evaluated in two controlled trials from the 1970s by the same principal investigator; both studies have significant methodologic flaws. In one supposedly randomized, double-blind, placebo-con­trolled study, adults with osteoarthritis or rheumatoid arthritis took 2-8 tablets daily of a saponin extract (amount unknown) from an unidentified desert yucca plant. Of 165 patients enrolled, 149 replied to a questionnaire after 1 week to 15 months of treatment. Subjective benefits were found in the yucca group in 49-77% of patients based on different types of questions, while only 21.5% of the placebo group indicated improvement. Although the results are suggestive of benefit, study weaknesses and poorly de­scribed methodology severely limit the value of the study. Only 17 of 51 placebo patients answered the questionnaire (other results were abstracted from charts); questionnaire results were incom­pletely reported for the placebo group; and randomization was flawed (at one site, all the patients received yucca tablets). In addition, duration of treatment and followup was highly variable, and compliance was not measured.

In the second study, of similar design, 2 tablets of yucca extract or placebo were given with each meal to 212 arthritic patients for up to 16 months to study the effects on cholesterol, triglycerides, and blood pressure. The investigators claimed that yucca reduced all three parameters compared to placebo. However, the study had similar design and methodologic weaknesses to those of the previous study. In addition, the data descriptions are confusing; there is no statistical analysis; and study "blinding" was faulty (the office nurses, who dispensed the tablets, were aware of which patients were in each group).

Adverse Effects:

In general, saponins may cause dose-dependent gastrointestinal distress, especially in raw plant form. In one of the controlled clinical trials using yucca tablets, mild and transient complaints were reported in about 9% of patients, and unfavorable gastrointestinal effects were reported in 4%. Native Americans and others have used the yucca plant as food for centuries without known adverse effects.

Side Effects and Interactions:

No interactions are recognized.

Cautions:

Safety in pregnant and breast-feeding women has not been established. Injected directly into the bloodstream, saponins can cause hemolysis.

Preparations & Doses:

Precise doses have not been established. In the clinical studies that used a yucca saponin extract, tablets were taken three times daily, usually with or after meals. The amount of yucca or saponin in each tablet, and other ingredients in the extract, were not described. Traditionally, herbalists have made decoctions by boiling the roots or young shoots in water.

Summary Evaluation:

Yucca is most commonly used for the inflammatory symptoms of arthritis. The one controlled study that claimed benefits for this condition was severely flawed. Similarly, effects on lipids and blood pressure are poorly characterized. Yucca appears to be safe and well tolerated, but there is no convincing evidence that it is effective in treating any medical disorder.