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Wild Yam

Scientific Name(s): Dioscorea villosa L.
Common Name(s): China root, Colic root, Devil's bones, Mexican wild yam, Rheumatism root, Wild yam root, Yuma

Medically reviewed by Drugs.com. Last updated on Nov 20, 2024.

Clinical Overview

Use

Clinical trials are generally lacking for topical formulations of Dioscorea for menopausal symptoms. Chinese yam polysaccharides have been evaluated in laboratory studies for potential as prebiotics, with varying results. Dioscorea oppositifolia tubers have been used as a saliva substitute.

Dosing

There are inadequate clinical trials on which to base dosing guidelines.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

A clinical study evaluating the daily consumption of wild yam reported no adverse events. Topical preparations of wild yam extract are relatively free from adverse effects. Based on a single study in rats, oral D. villosa should be avoided in people with compromised renal function.

Toxicology

Topical D. villosa (with an upper limit of 3.5% diosgenin) was not found to be systemically toxic or genotoxic. Food poisoning, likely due to residual toxic levels of pesticides in yam flour, has been reported.

Scientific Family

Botany

D. villosa is a twining vine native to the central southeastern US and found less frequently in the Appalachian region. It is a dioecious plant with inconspicuous white to greenish-yellow female flowers and smooth, heart-shaped leaves. Plant synonyms include Dioscorea hirticaulis Bartlett and D. villosa L. var. hirticaulis (Bartlett) H.E. Ahles.

There are more than 500 species of Dioscorea worldwide, with Chinese yam (D. oppositifolia), water yam (Dioscorea alata L.), and wild yam commonly studied.(PLANTS 2008)

History

Wild yam was popularized by the Eclectic medical movement in the 19th century for its supposed antispasmodic properties and was therefore prescribed for biliary colic and spasm of the bowel. It was also promoted for the relief of nausea in pregnancy and for amenorrhea and dysmenorrhea. Wild yam has been used for urinary tract infections, rheumatoid arthritis, cholera, nervous excitement, and flatulence.(Brinker 1996, Kong 2009) Currently, however, its use as a natural hormone supplement appears to be based on the unsupported concept that it is a natural source or precursor of progesterone.(Komesaroff 2001, Ulbricht 2003)

Chemistry

Extracts of D. villosa contain steroidal saponins, diosgenin, alkaloids, tannins, phytosterols, and starch.Safety Assessment 2004

Estrogenic compounds have been reported for D. alata.Cheng 2007

Analytical techniques for the identification of constituents have been described.Safety Assessment 2004

Uses and Pharmacology

Much of the current herbal use of wild yam is predicated on the misconception that the diosgenin contained in the product can be converted by the human body into steroid hormones, particularly progesterone, through the intermediate dehydroepiandrosterone. This notion appears to be based on historical interest in diosgenin as a synthetic precursor of cortisone.(Ulbricht 2003) However, evidence suggesting that diosgenin or dioscin can be converted into human hormones is lacking.(Komesaroff 2001)

GI

Chinese yam polysaccharides have been evaluated in laboratory studies for potential as prebiotics, with varying results.(Kong 2009, Iwata 2009) However, clinical studies are lacking.

D. oppositifolia (synonym Dioscorea batatas) tubers have been used as a saliva substitute.(Park 2010, Syed 2008)

Menopause

Topical formulations of Dioscorea are poorly evaluated, and it is unlikely that they are a source of progesterone.(Carroll 2006, Haimov-Kochman 2005, Kelley 2010) Estrogenic compounds have been reported for D. alata(Cheng2007) while weak effects on progesterone receptor activity in human breast cells have also been demonstrated in vitro.(Park 2009) Inhibition of human breast cancer MCF-7 cell proliferation was also shown in vitro for D. villosa extracts.(Park 2009) The Society of Obstetricians and Gynaecologists of Canada's revised clinical practice guidelines (2021) on managing menopausal vasomotor symptoms do not recommend wild yam for reducing menopausal symptoms based on a lack of evidence to support clinical benefit.(Yuksel 2021) Likewise, the Endocrine Society clinical practice guidelines for the treatment of symptoms of the menopause (2015) recommend counseling patients on the lack of consistent evidence for benefit of complementary medicine therapies, including wild yam, as an alternative nonhormonal therapy for vasomotor symptoms (weak recommendation; low quality evidence).(Stuenkel 2015) The North American Menopause Society position statement for nonhormonal management of menopause-associated vasomotor symptoms (2015) stated that due to a lack of efficacy data and potential harm from adulterants, yam creams are not recommended for vasomotor symptoms (Level II).(NAMS 2015)

Animal data

Research reveals no animal data regarding the use of wild yam for menopausal symptoms.

Clinical data

Limited clinical trials exist evaluating the effect of wild yam and its extract on menopausal symptoms. One uncontrolled clinical study evaluated the effect of consuming 390 g of yam over 30 days and found increases in serum estrone and sex hormone-binding globulin, but not in estradiol.(Wu 2005) Another randomized, double-blind, placebo-controlled trial evaluated daily topical application of D. villosa extract in menopausal women, finding no change in serum estrogen or progesterone, no effect on symptoms, and no effect on lipids, weight, or blood pressure.(Safety Assessment 2004, Komesaroff 2001) Commercial preparations of topical progesterone creams have been evaluated for use in managing menopausal symptoms (for more information see the Progesterone monograph).

Other uses

Isolated diosgenin decreased total cholesterol and increased high-density lipoprotein in rats.(Son 2007)

Allantoin from yam decreased plasma glucose in diabetic rats.(Niu 2010)

Dioscorin protein from the tuber of D. alata and Dioscorea japonica showed immune-stimulatory effects in mice(Liu 2009, Lin 2009) and exhibited hypotensive effects in rats.(Liu 2009)

D. alata was hepatoprotective in rats exposed to acetaminophen.(Lee 2002)

Wild yam was identified as one of the 4 most common herbs used for fertility, pre-term labor or bleeding by certified or licensed midwives in state-wide surveys conducted in California, Texas, and North Carolina.(Dennehy 2010)

Dosing

There are inadequate clinical trials on which to base dosing guidelines. Commercially available topical preparations of yam extracts recommend the application of 1 teaspoonful of cream twice daily.Komesaroff 2001 Based on a single study in rats, oral D. villosa should be avoided in people with compromised renal function.Wojcikowski 2008

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

A clinical study evaluating the consumption of yam 390 g per day reported no adverse events.Wu 2005 Topical preparations of wild yam extract are relatively free from adverse effects.Safety Assessment 2009, Komesaroff 2001

Acute animal toxicity studies reveal no reno- or hepatotoxicity.Wojcikowski 2008 A study in rats, however, found an increase in fibrosis in the kidneys and inflammation in the livers of rats fed D. villosa for 28 days.Wojcikowski 2008

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Toxicology

D. villosa has been evaluated in topical preparations with an upper limit of 3.5% diosgenin phytosterol and was not found to be systemically toxic or genotoxic. No data are available on the carcinogenicity of D. villosa.Safety Assessment 2004

Food poisoning from consumption of tainted yam flour was reported among 5 families in the capital of Kwara State, Nigeria in 2005. Adults, as well as children 3 to 10 years of age, experienced seizures and or GI symptoms (vomiting, abdominal pain, diarrhea) within minutes to hours after consuming yam flour served with a variety of sauces. Symptoms resolved within 24 to 48 hours after treatment. Based on concurrent seasonal and economic pressures in the country, it was suspected that due care was not used to process the yam chips into flour, which resulted in residual toxic levels of the pesticides aldrin and phosphine. The symptoms of toxicity of aldrin at low and moderate doses reflect those exhibited by these family members.Adedoyin 2008

Index Terms

References

Disclaimer

This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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