How It Works
Bottom Line: Wild yam has not been shown to prevent or treat cancer.
The roots of wild yam contain a compound called diosgenin, which showed hormonal effects that mimic estrogen and progesterone in animals. Diosgenin can be converted into other biologically active steroidal compounds in the lab and the semisynthetic form was used in early birth control pills. However, scientific study has found no evidence of such conversion in humans. A clinical trial of wild yam product on menopausal women showed no decrease in menopausal symptoms compared to a placebo.
Purported Uses
To relieve menopausal symptoms.
Wild yam had no effect on menopausal symptoms in a clinical trial.
To relieve menstrual dysfunction.
No scientific evidence supports this use.
To reduce anxiety.
This is not backed by any studies.
To treat colic.
No scientific evidence supports this use.
To improve cough.
There are no studies to support this.
To relieve colic and other spasms of the bowel.
No scientific evidence supports this use.
To relieve nausea during pregnancy.
There is only anecdotal evidence.
To treat rheumatoid arthritis.
No scientific evidence supports this use.
To treat urinary tract disorders.
This claim is not backed by clinical evidence.
Research Evidence
Menopausal Symptoms
Fifty women participated in a study to find out if wild yam is effective in relieving menopausal symptoms and if yam extract could be absorbed through the skin leading to increase in circulating hormones levels. Each woman applied either one teaspoonful of wild yam cream twice daily or a placebo to the arms, legs and abdomen externally for three months followed by cross-over to the other treatment type. Over half of the women dropped out of the trial because their symptoms were not improving. Of the women who completed the trial, no significant difference was observed in any of the menopausal symptom scores between wild yam and placebo. According to this trial, application of wild yam cream does not provide relief for menopausal symptoms better than placebo.
Warnings
Creams containing wild yam have been promoted as a natural source of the steroid progesterone, when in reality progesterone from other sources has been added to the cream.
This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. The product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.
Do Not Take If
You have hormone-sensitive cancer (wild yam has weak estrogenic activity).
Side Effects
Reported: large doses cause nausea, vomiting and diarrhea
(6).
Scientific Name
Dioscorea villosa
Common Name
Colic root, china root, devil's bones, rheumatism root, yuma, wild yam root
Brand Name
BioGest®
Clinical Summary
Derived from the root of a twining vine. Wild yam was traditionally thought to have antispasmodic properties and was promoted for gastrointestinal and menstrual dysfunction
(1). Diosgenin, a saponin found in wild yam was shown to have estrogenic and progestogenic effects in mice
(2) (3) (4) (9), but there is no scientific evidence that this substance can be converted by the body into human hormones
(1). It also demonstrated antiproliferative effects in vitro
(10), but failed to relieve menopausal symptoms
(5).
Side effects are minimal, however large doses can cause nausea, vomiting and diarrhea
(1). Patients should be warned that some wild yam extract creams have been promoted as a natural source of progesterone, when in reality they contain synthetic progesterone not connected to wild yam
(6).
Purported uses
Amenorrhea
Colic
Cough
Dysmenorrhea
GI disorders
Menopausal symptoms
Pregnancy-related nausea and vomiting
Rheumatoid arthritis
Sexual dysfunction
Spasms
Urinary tract disorders
Mechanism of Action
Most theories suggest that the active ingredient in wild yam is the steroid saponin, diosgenin. Diosgenin has been shown to stimulate mammary gland growth
(2) and reduce body weights
(3) in ovariectomized mice. Diosgenin does not exist freely in wild yam but rather as the saponins dioscin and gracillin. It is thought that diosgenin can be converted by the human body into progesterone and other steroid hormones via dehydroepiandrosterone (DHEA). No scientific evidence supports this theory of internal conversion
(1) (6).
Pharmacokinetics
Animal studies show that diosgenin is poorly absorbed. The absorbed portion is quickly distributed into the liver, adrenals and walls of the gastrointestinal tract and undergoes extensive biotransformation. Diosgenin and the metabolites are eliminated through the bile and excreted in the feces
(7) (8).
Warnings
Patients should be warned that creams containing extracts of wild yam have been promoted as a natural source of progesterone, when in reality they contain synthetic progesterone not connected to wild yam
(6).
Contraindications
Patients with hormone-sensitive cancers should avoid wild yam because it has weak estrogenic activity.
Literature Summary and Critique
References
- DerMarderosian A. The Review of Natural Products. St. Louis: Facts and Comparisons, 1999.
- Aradhana, Rao AR, Kale RK. Diosgenin--a growth stimulator of mammary gland of ovariectomized mouse. Indian J Exp.Biol 1992;30:367-70.
- Benghuzzi H, Tucci M, Eckie R, Hughes J. The effects of sustained delivery of diosgenin on the adrenal gland of female rats. Biomed.Sci.Instrum. 2003;39:335-40.
- Accatino L, Pizarro M, Solis N, Koenig CS. Effects of diosgenin, a plant-derived steroid, on bile secretion and hepatocellular cholestasis induced by estrogens in the rat. Hepatology 1998;28:129-40.
- 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;4:144-50.
- Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. New York: Springer, 2001.
- Cayen MN, Ferdinandi ES, Greselin E, Dvornik D. Studies on the disposition of diosgenin in rats, dogs, monkeys and man. Atherosclerosis 1979;33:71-87. PM:
- Juarez-Oropeza MA, Diaz-Zagoya JC, Rabinowitz JL. In vivo and in vitro studies of hypocholesterolemic effects of diosgenin in rats. Int J Biochem. 1987;19:679-83.
- Park MK, Kwon HY, Ahn WS, et al. Estrogen activities and the cellular effects of natural progesterone from wild yam extract in mcf-7 human breast cancer cells. Am J Chin Med. 2009;37(1):159-67.
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Wojcikowski K, Wohlmuth H, Johnson DW, Gobe G. Dioscorea villosa (wild yam) induces chronic kidney injury via pro-fibrotic pathways. Food Chem Toxicol. 2008 Sep;46(9):3122-31.
