Thursday, December 31, 2009

Medicinal Herbs: Wild Yam

Wild yam

Overview

In the 18th and 19th centuries, herbalists used wild yam (Dioscorea villosa ) to treat menstrual cramps and problems related to childbirth, as well as for stomach upset and coughs. In the 1950s, scientists discovered that the roots of wild yam (not to be confused with the sweet potato yam) contain diosgenin, a phytoestrogen (derived from plants) that can be chemically converted into a hormone called progesterone. Diosgenin was used to make the first birth control pills in the 1960s.

Although herbalists continue to use wild yam to treat menstrual cramps, nausea, and morning sickness associated with pregnancy, inflammation, osteoporosis, menopausal symptoms, and other health conditions, there is no evidence that it works. Indeed, several studies have found that it has no effect at all. That is because the body cannot change diosgenin into progesterone; it has to be done in a lab. Wild yam, by itself, does not contain progesterone.

General

Early Americans used wild yam to treat colic; another name for the plant is colic root. Traditionally, it has been used to treat inflammation, muscle spasms, and a range of disorders, including asthma. However, there is no scientific evidence that it works.

Menopause and Osteoporosis

Although wild yam is often touted as a natural source of estrogen, there is essentially no scientific evidence of wild yam's effectiveness in treating menopausal symptoms or osteoporosis. In fact, several studies have found that wild yam does not reduce the symptoms of menopause (such as hot flashes) or increase levels of estrogen or progesterone in the body. Some preparations of wild yam may contain progesterone, but only because a synthetic version of progesterone (medroxyprogesterone acetate or MPA) has been added to the herb.

High Cholesterol

Researchers have theorized that taking wild yam may help reduce levels of cholesterol in the blood, although studies have shown mixed results. Diosgenin seems to block the body from absorbing cholesterol, at least in animal studies. But in studies of people, cholesterol levels have not gone down (although fats -- triglycerides -- in the blood have decreased). More research is needed to say whether wild yam is beneficial for people with high cholesterol.

Plant Description

Also known as colic root, wild yam is a twining, tuberous vine. One species is native to North America; another is native to China. Both contain diosgenin and have similar medicinal properties. There are an estimated 600 species of yam in the genus Dioscorea, many of them wild species that flourish in damp woodlands and thickets, and not all contain diosgenin. Wild yam is a perennial vine with pale brown, knotty, woody cylindrical rootstocks, or tubers. Unlike sweet potato yams, the roots are not fleshy. Instead they are dry, narrow, and 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, greenish-white and greenish-yellow flowers. The heart-shaped leaves are long and broad and long-stemmed. The upper surface of the leaves is smooth while the underside is downy.

What's it Made of?

The dried root, or rhizome, is used in commercial preparations. It contains diosgenin, a phytoestrogen that can be chemically converted to the hormone progesterone; however, diosgenin on its own does not seem to act like estrogen in the body.

Available Forms

Wild yam is available as liquid extract and as a powder. The powdered form may be purchased in capsules or compressed tablets. The fluid extract can be made into tea. Creams containing wild yam are also available.

How to Take It

Pediatric

It is not known whether wild yam is safe for pediatric use, so do not give it to children.

Adult

The following are recommended adult doses for wild yam:

  • Dried herb to make tea: 1 - 2 tsp dried root to 1 cup water. Pour boiling water over dried root, steep 3 - 5 minutes. Drink 3 times a day
  • Tincture: 40 - 120 drops, 3 times a day
  • Fluid extract: 10 - 40 drops, 3 - 4 times per day
  • Creams: Contain 12% of wild yam extract; use as directed

Note: Wild yam is often combined with other herbs said to have estrogen-like effects, such as black cohosh. Creams containing wild yam, as well as tablets and powders, may contain synthetic hormones. Check the ingredients carefully.

Precautions

The use of herbs is a time-honored approach to strengthening the body and treating disease. Herbs, however, can trigger side effects and can interact with other herbs, supplements, or medications. For these reasons, you should take herbs with care, under the supervision of a health care provider.

Although it does not appear to have hormone-like effects in the body, there is a slight risk that wild yam could produce effects similar to estrogen. Because of that risk, anyone with a personal or family history of hormone-related cancer should check with their doctor before using any form of "natural" hormone replacement, including wild yam.

Pregnant women and nursing mothers should avoid wild yam.

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 health care provider.

Hormone Replacement Therapy or Birth Control Pills -- 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 also is used in some birth control medications and certain hormone replacement therapies.

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