Wild yam

Botanical Name:  Dioscorea villosa

Overview

In the 18th and 19th centuries, wild yam (Dioscorea villosa) was used by herbalists 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 is involved in the production of the hormone progesterone. Diosgenin has served a key role in the making 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, nausea and morning sickness associated with pregnancy, inflammation, osteoporosis, menopausal symptoms, and other health conditions.

Plant Description

Also known as colic root, wild yam is a twining, tuberous vine native to North America. 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 horizontal branches of long creeping runners. The thin reddish-brown stems grow to a length of over 30 feet. The roots initially taste starchy, but soon after taste bitter and acrid.
The wild yam plant has clusters of small, drooping greenish-white and greenish-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.

Parts Used

The dried root, or rhizome, is used in commercial preparations.

Medicinal Uses and Indications

General
Early Americans used wild yam to treat colic; hence, the term colic root. Traditionally, it has been used to treat inflammation, muscle spasms and a range of disorders including asthma. Related species of Dioscorea are used in the Amazon and in central America to treat conditions including fever, urinary tract infections, colds, rheumatism (joint and muscle related conditions), arthritis, hemorrhoids, boils, and dysentery.
Menopause and Osteoporosis
While the diosgenin found in wild yam created quite a stir in the 1990s as a cure for menopausal disorders and other symptoms of aging in women, the plant itself has no proven hormonal action, nor have any studies shown it to be effective in treating hormone related disorders. It is true that diosgenin can be converted into steroidal compounds, which are then used in the chemical synthesis of progesterone, but this is in the laboratory—not in the human body. There is essentially no scientific evidence of wild yam's effectiveness in treating menopausal symptoms or osteoporosis. Although many individuals claim relief of symptoms such as vaginal dryness with the use of progesterone creams, some of which contain an extract of Dioscorea villosa, no well-designed studies have evaluated these creams. Moreover, many products that claim to contain natural progesterone actually contain synthetic medroxyprogesterone acetate (MPA).
Available Forms
Wild yam is available as liquid extract and powdered tuber products. The powdered form may be purchased in capsules or compressed tablets. The fluid extract can be made into tea.

How to Take It

Pediatric
It is unclear whether wild yam is safe in children; therefore, use should be specifically directed by a knowledgeable healthcare practitioner and limited to one week.
Adult
The following are recommended adult doses for wild yam:

• Dried herb to make tea: 1 to 2 tsp dried root to 1 cup water. Pour boiling water over dried root, steep 3 to 5 minutes. Drink three times a day
• Tincture: 40 to 120 drops, three times a day
• Fluid extract: 10 to 40 drops, three to four times per day

Precautions

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, contain active substances that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, herbs should be taken with care, under the supervision of a practitioner knowledgeable in the field of botanical medicine. Because wild yam contains dioscorin, a substance that can be toxic, it is particularly important to stay within the recommended dosages.

Possible Interactions

If you are currently being treated with any of the following medications, you should not use wild yam without first talking to your healthcare provider.
Estradiol
An animal study indicated that the active component of wild yam, diosgenin, may interact with estradiol, a hormone that occurs naturally in the body and that is also used in some birth control medications and certain hormone replacement therapies.