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WILD YAM (Dioscorea villosa and other Dioscorea spp.)

Family: Dioscoreaceae
Synonyms: Colicroot, Rheumatism root (1), Wilde Yamwurzel (2), Atlantic yam, China Root, Mexican Yam, Yuma, Natural DHEA, Phytoestrogen (3).

Downloadable PDF of this information sheet

Plant characteristics

Wild yam is a member of the Yam family. The yams are vining plants with 600 known species, 71 of which are native to North America (67 species in Mexico) (4). In many species of yam, the rhizome (tuber) serves as both a food and a medicine (4).

Dioscorea villosa, the species common in North Carolina, is a perennial vine that grows in moist thickets and hedges (4, 5). It has a reddish-brown stem, heart-shaped leaves with prominent veins, and inconspicuous greenish yellow flowers in September and October.

Farmers world-wide cultivate yams as a food source and harvest the roots in the fall (6). Herbalists prepare medicines from fresh or dried root (2, 6).

Herb medicinal properties

Biologically-active chemicals: saponins (including diosgenin) and isoquinuclidine alkaloids (including dioscorin) (7). Diosgenin is a steroid precursor. Researchers and manufacturers have used it to create estrogens, progesterones, androgens, and corticosteroids (3). It is important to recognize that the body DOES NOT converts diosgenin into any of these hormones.

Herbal properties: antispasmodic, anti-inflammatory, anti-rheumatic, cholagogue, diaphoretic, and expectorant (1, 6).

How herb was used traditionally

Known to indigenous Americans (2) and early colonial doctors as a treatment for rabies (8). Subsequently used to treat a variety of nervous complaints, including “female weakness” (8), epilepsy and uncontrollable movements (7). Was in The United States Pharmacopeia from 1863-1916 and in The National Formulary until 1947.

Aztecs used wild yam externally to treat scabies and boils (4). Other Native Americans used a decoction of the root to relieve labor pain and later physicians gave wild yam to patients with colic, morning sickness, asthma, hiccough, rheumatism and gastritis related to alcoholism (5). Modern herbalists value wild yam to treat intestinal colic, biliary colic, and flatulence as well as menstrual cramps and rheumatoid arthritis (1, 7, 8) Herbalists combine wild yam with black cohosh (6) (and sometimes burdock root and motherwort) (4) for rheumatic complaints. Chinese herbalists use wild yam as a tonic (4).

Currently, manufacturers market wild yam as a treatment for treatment of menopausal symptoms (9).

Preparation and dosage:
Traditionally administered as a tea (1-2 grams in 1 cup of boiling water three times daily) or an alcohol-based tincture (1/2- 1 teaspoon of a 1:3 strength tincture three times daily) (9).

How herb is used today (based on scientific evidence)

Few clinical studies of wild yam have been undertaken. One study showed that wild yam cream was not effective for treating menopausal symptoms.

Wild yam is a component of many products including products to increase libido, enlarge the breasts, treat menopause, improve physical prowess in sports, and treat PMS. The evidence for such uses of wild yam is lacking (3). It is interesting that current use patterns focus on the herb's steroid precursor component and ignore traditional uses.

Preparation and dosage:

• Boil 1-2 teaspoons of dried root in one cup of water for 15 minutes and drink three times daily

• Or take 2-4 ml of the tincture (1:5 strength).

Safety issues

Side effects: Vomiting at high doses (3).
Adverse events: None reported for Dioscorea villosa. A related species, from Java contains a weak picrotoxin, a convulsive poison (2).
Precautions/contraindications: No information exists regarding safety in pregnant women and children. Dioscorea species are consumed as food around the world.
Interactions with pharmaceuticals: None known (3).
Interactions with other herbs: No negative interactions known. Herbalists combine wild yam with other anti-spasmodic herbs to achieve the desired effect on joint pain and colic (10).

References

1.               M. Tierra, The Way of Herbs (Pocket Books, New York, 1998).

2.               M. Grieve, A Modern Herbal (Dover Publications, Inc, New York, 1971), pp.

3.               J. M. Jellin, P. J. Gregory, F. Batz, K. Hitchens. (Therapeutic Research Faculty, Stockton, CA, 2004), vol. 2004.

4.               A. R. Hutchens, Indian Herbology of North America (Shambhala Publications, Inc., Boston, 1991), pp.

5.               S. Foster, J. Duke, A Field guide to Medicinal Plants and Herbs of Eastern and Central North America, The Peterson Field Guide Series (Houghton Mifflin, New York, 2000), pp.

6.               D. Hoffman, The New Holistic Herbal (Element, Boston, MA, 1990), pp.

7.               J. Gruenwald, T. Brendler, C. Jaenicke, M. Mehtoa, Eds., PDR for Herbal Medicines (Medical Economics Company, Inc., Montvale, NJ, 1998), pp.

8.               D. Hoffman, Medical Herbalism (Healing Arts Press, Rochester, Vermont, 2003), pp.

9.               L. Russell, G. S. Hicks, A. K. Low, J. M. Shepherd, C. A. Brown, Am J Med Sci 324, 185 (Oct, 2002).

10.             A. Huntley, E. Ernst, Menopause 10, 58 (Jan-Feb, 2003).

11.             Strategic Reports, Analysis of the economic viability of cultivating selected botanicals in North Carolina. A report commissioned for the North Carolina Consortium on Natural Medicinal Products (North Carolina State University, 2002.).

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