Herbalists and pharmaceutical manufacturers alike have long recognized wild yam's medicinal benefits. In the 18^th and 19^th centuries, this herb was used to treat menstrual cramps and problems related to childbirth. The subsequent discovery of a substance contained in wild yams revolutionized the pharmaceutical industry. The tubers, or fleshy, root-like parts, of wild yams (not to be confused with the sweet potato yam) contain diosgenin, a steroid-like substance that can be converted into the female hormone progesterone. Diosgenin has served a key role in the synthesis of hormones and the development of the birth control pill, two of the major advances in plant drug medicine this century. Wild yam continues to be used for treating menstrual cramps, and nausea and morning sickness associated with pregnancy, as well as inflammation, osteoporosis, spasm, and other health conditions.

Wild yam (Dioscorea villosa) is native to Canada and the southern United States. It is one of an estimated 600 species of yam in the genus Dioscorea, many of them wild species that flourish in damp woodlands and thickets. Wild yam is a perennial, twining vine with pale brown, knotty, woody cylindrical rootstocks, or tubers. The rootstocks are crooked, and bear sideways branches of long creeping runners. The thin reddish-brown stems grow to a length of 5 to 12 meters. The roots initially taste starchy, but soon after taste bitter and acrid.

The wild yam plant has clusters of small, drooping green-white to green-yellow flowers. The heart-shaped leaves are long and broad and long-stemmed, with prominent veins. The upper surface of the leaves is smooth while the underside is downy.

The dried rhizome with roots are used in commercial preparations.

Wild yam is used to treat the following conditions and symptoms:

• Menstrual cramps
• Nausea
• Intestinal colic
• Inflammation
• Spasm
• Rheumatoid arthritis
• Gallbladder colic
• Ulcerative colitis 

This plant also produces sweat and stimulates the flow of bile to the duodenum, a part of the small intestine. Many women also claim that wild yam (when used as a cream) improves menopausal symptoms, particularly vaginal dryness. Unfortunately, the value of wild yam for menopausal symptoms has not yet been fully evaluated in people or in animals.

Wild yam is available as liquid extract and powdered tuber products.

Pediatric

• Adjust the recommended adult dose to account for the child's weight. Most herbal dosages for adults are calculated on the basis of a 150 lb (70 kg) adult. Therefore, if the child weighs 50 lb (20 to 25 kg), the appropriate dose of wild yam for this child would be 1/3 of the adult dosage.
• Use in children should be limited to 1 week.

Adult

The following are recommended adult doses for wild yam:

• Dried herb: 1 to 2 tsp three times a day
• Tincture: 2 to 4 mL three times a day

Overdosing can be potentially poisonous because a substance within wild yam can be toxic.

An animal study indicated that the active component of wild yam, diosgenin, may interact with estradiol. You should consult with your doctor before using wild yam if you are currently taking this medication.

Aikman L. Nature's Healing Arts: From Folk Medicine to Modern Drugs. Washington, DC: National Geographic Society; 1977:186-189, 196.

Arvigo R, Balick M. Rainforest Remedies:One Hundred Healing Herbs of Belize. Twin Lakes, Wis: Lotus Press; 1993: 194-195.

British Herbal Pharmacopoeia. 4th ed. Great Britain: Biddles Ltd, Guildford and King's Lynn; 1996:187.

Dorland's Illustrated Medical Dictionary. 25th ed. Philadelphia, Pa: W.B. Saunders; 1974.

Duke JA. The Green Pharmacy. New York, NY:St Martin's Press; 1997:111, 209-210, 352

Duke JA. Phytochemical Database, USDA–ARS–NGRL, Beltsville Agricultural Research Center, Md. Available at: www.ars-grin.gov/duke/ 

Duke J, Vasquez R. Amazonian Ethnobotanical Dictionary. Boca Raton, Fla: CRC Press; 1994:66-67.

Etkin N, ed. Plants in Indigenous Medicine and Diet: Biobehavioral Approaches. Bedford Hills, NY: Redgrave Publishing; 1986: 131-150.

Grieve M. A Modern Herbal. Vol. II. New York, NY: Dover; 1971:863.

Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company; 1998:809-810.

Mabberley DJ. The Plant-Book: A Portable Dictionary of the Higher Plants. England: Cambridge University Press; 1987: 185

Thomson WA, ed. Medicines from the Earth: A Guide to Healing Plants. Maidenhead, England: McGraw-Hill Book Company; 1978:61.

Vasiukova N, Paseshnichenko V, Davydova M, Chalenko G. Pharmacological evaluation of Dioscorea dumetorum tuber used in traditional antidiabetic therapy. J Ethnopharmacol. 1986;15(ISS 2):133-144.

White L, Mavor S. Kids, Herbs, Health. Loveland, Colo: Interweave Press; 1998:22, 43.