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Other common
name(s): wild Mexican yam, colic root, rheumatism root,
Chinese yam, shan yao
Scientific/medical
name(s): Dioscorea
villosa, Dioscorea oppositifolia or Dioscorea opposita, Dioscorea
batatas
Description
Wild yam is a perennial vine, also known as the wild Mexican
yam or Dioscorea villosa,
which is native to North America. A similar variety called the Chinese
yam is an ornamental plant native to China that now grows in North
America as well. It is known as Dioscorea
oppositifolia and Dioscorea
batatas but is called shan
yao in Chinese herbal medicine. The roots and rootstock,
or rhizomes, of both types of yam are used in herbal remedies. These
plants are different from the yams and sweet potatoes commonly eaten in
North America.
Overview
Although creams and oral supplements containing wild yam
extracts are popular among women as an alternative to postmenopausal
hormone therapy, available scientific evidence does not support claims
that they are safe or effective. Neither estrogen nor progesterone can
be found in wild yams, although these yams may contain compounds that
have effects similar to, but milder than, estrogen. Some wild yam
creams have synthetic (sometimes called "natural") progesterone added
to them.
How is it promoted for use?
The wild Mexican yam and the Chinese yam are 2 types of yams
that are promoted in similar ways. Proponents claim that a cream made
from the wild Mexican yam contains natural progesterone (a hormone that
plays a vital role in women's health) and is therefore effective in
treating premenstrual syndrome (PMS) and menstrual irregularity, as
well as hot flashes and other symptoms of menopause. Supporters say
that using wild yam as an alternative to postmenopausal hormone therapy
significantly lowers the risk of breast and endometrial cancer.
Marketers also claim that their product helps women lose weight,
increases energy and stamina, and enhances sex drive. A few marketers
imply that wild yam can be used as herbal birth control. By contrast,
some suggest that it improves fertility. It is also recommended to
enlarge breasts and reduce wrinkles.
Supporters claim that the wild Mexican yam, when taken
internally, helps arthritis pain, morning sickness, painful
menstruation, bronchitis, asthma, whooping cough, cramps, and
intestinal ailments such as Crohn’s disease, colitis, and
chronic diarrhea.
The Chinese yam is claimed to stimulate appetite and to be a
remedy for chronic diarrhea, asthma, fatigue, uncontrollable or
frequent urination, diabetes, and emotional instability. Proponents
claim the Chinese yam can be used externally to speed the healing of
boils and abscesses. Herbalists also use it to treat colic because it
is thought to relieve intestinal spasms.
What does it involve?
Creams or gels made from wild yams are rubbed directly onto
the skin and are available from health food stores and on the Internet.
Some of these creams have synthetic, or man-made, progesterone added to
them, although most don’t advertise this addition; if they
do, it is often mentioned as natural progesterone. Wild yam is also
sold as a capsule, liquid, dried root, and tincture to be taken by
mouth. Some sellers combine it with vitamins, minerals, or other herbs,
such as black cohosh (see Black Cohosh).
In homeopathic medicine, the wild yam from the Dioscorea villosa
plant is used fresh or dried and put in liquid extracts (see Homeopathy).
The Chinese yam can also be used fresh or baked with flour or clay.
Wild yam capsules and other forms are available in herbal shops and
over the Internet. Dosages vary by manufacturer.
What is the history behind it?
In East Indian traditional medicine, the wild yam is used to
treat sexual and hormonal problems. Chinese herbalists have long used
the herb for rheumatism, asthma, and digestive and urinary complaints.
Wild yam has also been used in American folk medicine to treat coughs
and to induce sweating and vomiting. Some sources suggest that Native
Americans and early settlers used it for its ability to relieve
intestinal spasms, which is how it got the name colic root.
In the 1960s, progesterone and other steroid hormones were
chemically manufactured, in part using ingredients from the Mexican
wild yam. This may be the reason for the misconception that the
progesterone "precursors" in wild yam could be converted into
progesterone in the body.
Some wild yam creams have been found to contain added
synthetic progesterone.
What is the evidence?
Contrary to claims, wild yam cannot supply the body with
progesterone. The plant contains the chemical diosgenin, which can be
converted into a synthetic form of progesterone through a lengthy
process in the laboratory. There is no available scientific evidence
that suggests the body can convert diosgenin into progesterone. Some of
the chemicals in the plant resemble a weak form of estrogen, another
hormone that is important in female physiology, but
estrogen’s effects on the body are very different from those
of progesterone. Drugs manufactured from diosgenin are used to treat
asthma, arthritis, eczema, and to control fertility.
Available scientific evidence does not support claims that the
wild yam can help the symptoms of menopause or premenstrual syndrome,
reduce wrinkles, or enlarge breasts. However, since progesterone is
absorbed through the skin and mucous membranes, a wild yam cream with
added progesterone can have pharmacologic effects on the whole body.
Are there any possible problems or
complications?
This product is sold as a
dietary supplement in the United States. Unlike companies that produce
drugs (which must provide the FDA with results of detailed testing
showing their product is safe and effective before the drug is approved
for sale), the companies that make supplements do not have to show
evidence of safety or health benefits to the FDA before selling their
products. Supplement products without any reliable scientific evidence
of health benefits may still be sold as long as the companies selling
them do not claim the supplements can prevent, treat, or cure any
specific disease. Some such products may not contain the amount of the
herb or substance that is written on the label, and some may include
other substances (contaminants). Though the FDA has written new rules
to improve the quality of manufacturing processes for dietary
supplements and the accurate listing of supplement ingredients, these
rules do not take full effect until 2010. And, the new rules do not
address the safety of supplement ingredients or their effects on health
when proper manufacturing techniques are used.
Most such
supplements have not been tested to find out if they interact with
medicines, foods, or other herbs and supplements. Even though some
reports of interactions and harmful effects may be published, full
studies of interactions and effects are not often available. Because of
these limitations, any information on ill effects and interactions
below should be considered incomplete.
Large doses of wild yam can cause nausea, vomiting, and
diarrhea. Women who are pregnant or breast-feeding should not use wild
yam. Although rare, allergic reactions to wild yam can occur, including
rashes, asthma, and other symptoms.
There are several problems with using wild yam creams with
added progesterone. They are often not labeled as containing added
progesterone, and the amount in the cream varies. Even if the amount of
progesterone in the cream was consistent and declared, the body absorbs
progesterone in different amounts at different times and from different
places on the body. This means that any effect on the body is
unreliable. In addition, progesterone can have side effects such as
headache, breast tenderness, upset stomach, constipation, tiredness,
and irritability. In rare cases, there can be serious side effects,
such as dizziness, faintness, shortness of breath, blurred vision,
seizures, and swelling of the lips, mouth, or throat. Relying on this
type of treatment alone and avoiding or delaying conventional medical
care for cancer may have serious health consequences.
Additional Resources
More information from your American Cancer
Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be found on
our Web site (www.cancer.org)
or ordered from our toll-free number (1-800-ACS-2345).
References
Bown D. New
Encyclopedia of Herbs & Their Uses. New York, NY:
DK Publishing Inc; 2001.
Burry KA, Patton PE, Hermsmeyer K. Percutaneous absorption of
progesterone in postmenopausal women treated with transdermal estrogen.
Am J Obstet Gynecol.
1999;180:1504-1511.
Carey BJ, Carey AH, Patel S, Carter G, Studd JW. A study to
evaluate serum and urinary hormone levels following short and long term
administration of two regimens of progesterone cream in postmenopausal
women. BJOG.
2000;107:722-726.
Foster S, Duke JA. A
Field Guide to Medicinal Plants: Eastern and Central North America.
Boston, MA: Houghton Mifflin; 1990.
Fugh-Berman A. "Bust enhancing" herbal products. Obstet Gynecol.
2003;101:1345-1349.
Fugh-Berman A. Wild yam cream, diosgenin, and natural
progesterone: What can they really do for you? National Women's Health
Network. The Network
News. January 1, 1999.
Gorski T. "Wild yam cream" threatens women’s health.
Quackwatch Web site.
http://www.quackwatch.org/01QuackeryRelatedTopics/wildyam.html. Updated
July 19, 2002. Accessed June 9, 2008.
Komesaroff PA, Black CV, Cable V, Sudhir K. Effects of wild
yam extract on menopausal symptoms, lipids and sex hormones in healthy
menopausal women. Climacteric.
2001;4:144-150.
Progesterone. Medline Plus Web site.
http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a604017.html.
Updated July 1, 2004. Accessed June 9, 2008.
Tu M. Element stewardship abstract for dioscorea oppositifolia
l. syn. dioscoria batatas (decne): chinese yam, cinnamon vine.
http://tncweeds.ucdavis.edu/esadocs/documnts/diosopp.rtf. Accessed June
9, 2008.
Wild Yam (Discorea villosa). Medline Plus Web site.
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-wildyam.html.
Updated February 1, 2008. Accessed June 9, 2008.
Wild yam. Memorial Sloan-Kettering Cancer Center Web site.
http://www.mskcc.org/mskcc/html/69420.cfm. Updated July 20, 2007.
Accessed June 9, 2008.
Wild yam. Whole Health MD Web site.
http://www.wholehealthmd.com/ME2/dirmod.asp?sid=17E09E7CFFF640448FFB0B4FC1B7FEF0&nm=Reference+Library&type=AWHN_Supplements&mod=Supplements&mid=&id=8BD6A74701414C1C9131AC1DE48FC415&tier=2.
Updated September 12, 2005. Accessed June 9, 2008.
Note: This information may not cover
all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Last Medical Review: 11/01/2008
Last Revised: 11/01/2008
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