Wild Yam

• How It Works

  Wild yam has not been shown to prevent or treat cancer.

  Wild yam contains a compound called diosgenin that mimics estrogen and progesterone in animals. Diosgenin can be converted into active steroid compounds in the lab. Small studies using different species and formulas of wild yam extract have had mixed results on menopausal symptoms. Another small study suggests that increasing yam intake through diet may improve sex hormone and cholesterol levels. A lab study showed that wild yam extract has weak hormonal activity against human breast cancer cells, but this does not mean it can prevent or treat cancer.

  More studies are needed to confirm whether wild yam or its extract actually has any benefits. Because wild yam has estrogenic effects, patients with hormone-sensitive cancers should talk to their physicians before consumption.

• Purported Uses
  • To relieve menopausal symptoms
    Wild yam has had mixed results in small studies. More research is needed.
  • To improve cough
    Supporting evidence is lacking.
  • To treat rheumatoid arthritis
    Supporting evidence is lacking.
• Side Effects
  • Animal studies have shown wild yam extract may cause kidney injury. But clinical significance is not known.
• Scientific Name

  Dioscorea villosa, Dioscorea alata

• Clinical Summary

  Derived from the root of a twining vine, wild yam was traditionally used for its antispasmodic and anti-inflammatory properties to treat menopausal symptoms, gastrointestinal ailments, muscle spasm, asthma, joint pain, and rheumatoid arthritis ^(1) (2). Wild yam has antiproliferative ⁽³⁾ and antimitotic effects ⁽⁴⁾ in vitro, and animal models also suggest it has antinociceptive and anti-inflammatory properties  ^(1) (18). Diosgenin, the active ingredient in wild yam, was shown to have estrogenic and progestogenic effects ^{(3) (5) (6) (7) (19)}, and to restore moderately decreased sperm motility ⁽²⁰⁾ in mice. Dioscorin, another protein, was shown to lower weight gain, total visceral lipids, and impaired glucose tolerance in mice ⁽²¹⁾.

  Two small studies on whether wild yam can relieve menopausal symptoms had opposing results, with one demonstrating an oral D. alata formula to be more effective than placebo ⁽⁸⁾, but another study showing a topical D. villosa formula to be ineffective ⁽⁹⁾. A study of dietary yam was found to improve sex hormone and lipid profiles ⁽¹⁰⁾. More studies are needed to confirm whether dietary or supplemental wild yam actually has any benefits for menopausal symptoms. Consuming an oral diosgenin-rich yam extract was shown to enhance cognitive function ⁽²²⁾.

  Wild yam extract is sold as a dietary supplement, liquid extract or as a cream. Diosgenin in wild yam has been used as raw material for synthetic progesterone, but there is no evidence that the human body can convert diosgenin into progesterone. Because wild yam has estrogenic effects, patients with hormone-sensitive cancers should talk to their physicians before consumption.

• Purported Uses
  • Cough
  • Menopausal symptoms
  • Rheumatoid arthritis
  • Spasms
• Mechanism of Action

  The steroid saponin diosgenin in wild yam modulates cell signaling involved in growth, differentiation, apoptosis, and oncogenesis ⁽¹⁴⁾. In vitro studies suggest wild yam extract protects against human breast cancer proliferation by acting as a weak phytoestrogen ⁽³⁾. A molecular docking study of estrogen mimics in phytochemicals from dietary herbal supplements found that D. villosa docked strongly with the estrogen receptor ⁽²³⁾. However, the D. villosa species has been noted to induce chronic kidney injury via pro-fibrotic pathways in animal models ⁽¹⁵⁾.

• Adverse Reactions

  Animal models indicate a potential for kidney injury. However, the clinical relevance is not known ⁽¹⁵⁾.

• References

  1. Lima CM, Lima AK, Melo MG, et al. Bioassay-guided evaluation of Dioscorea villosa — an acute and subchronic toxicity, antinociceptive and anti-inflammatory approach. BMC Complement Altern Med. Jul 28 2013;13(1):195.

  2. Manda VK, Avula B, Ali Z, et al. Characterization of in vitro ADME properties of diosgenin and dioscin from Dioscorea villosa. Planta Med. Oct 2013;79(15):1421-1428.

  3. 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):159-167.

  4. Mazzio E, Badisa R, Mack N, et al. High Throughput Screening of Natural Products for Anti-mitotic Effects in MDA-MB-231 Human Breast Carcinoma Cells. Phytother Res. Sep 17 2013.

  5. Aradhana, Rao AR, Kale RK. Diosgenin—a growth stimulator of mammary gland of ovariectomized mouse. Indian J Exp Biol. May 1992;30(5):367-370.

  6. Benghuzzi H, Tucci M, Eckie R, et al. The effects of sustained delivery of diosgenin on the adrenal gland of female rats. Biomed Sci Instrum. 2003;39:335-340.

  7. Accatino L, Pizarro M, Solis N, et al. Effects of diosgenin, a plant-derived steroid, on bile secretion and hepatocellular cholestasis induced by estrogens in the rat. Hepatology. Jul 1998;28(1):129-140.

  8. Hsu CC, Kuo HC, Chang SY, et al. The assessment of efficacy of Diascorea alata for menopausal symptom treatment in Taiwanese women. Climacteric. Feb 2011;14(1):132-139.

  9. Komesaroff PA, Black CV, Cable V, et al. Effects of wild yam extract on menopausal symptoms, lipids and sex hormones in healthy menopausal women. Climacteric. Jun 2001;4(2):144-150.

  10. Wu WH, Liu LY, Chung CJ, et al. Estrogenic effect of yam ingestion in healthy postmenopausal women. J Am Coll Nutr. Aug 2005;24(4):235-243.

  11. Yoon KD, Chin YW, Yang MH, et al. Application of high-speed countercurrent chromatography-evaporative light scattering detection for the separation of seven steroidal saponins from Dioscorea villosa. Phytochem Anal. Sep-Oct 2012;23(5):462-468.

  12. Dong SH, Nikolic D, Simmler C, et al. Diarylheptanoids from Dioscorea villosa (wild yam). J Nat Prod. Dec 28 2012;75(12):2168-2177.

  13. Dong SH, Cai G, Napolitano JG, et al. Lipidated steroid saponins from Dioscorea villosa (wild yam). Fitoterapia. Dec 2013;91:113-124.

  14. Raju J, Mehta R. Cancer chemopreventive and therapeutic effects of diosgenin, a food saponin. Nutr Cancer. 2009;61(1):27-35.

  15. Wojcikowski K, Wohlmuth H, Johnson DW, et al. Dioscorea villosa (wild yam) induces chronic kidney injury via pro-fibrotic pathways. Food Chem Toxicol. Sep 2008;46(9):3122-3131.

  16. Cayen MN, Ferdinandi ES, Greselin E, et al. Studies on the disposition of diosgenin in rats, dogs, monkeys and man. Atherosclerosis. May 1979;33(1):71-87.

  17. 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(8):679-683.

  18. Chen T, Hu S, Zhang H, Guan Q, Yang Y, Wang X. Anti-inflammatory effects of Dioscorea alata L. anthocyanins in a TNBS-induced colitis model. Food Funct. Feb 22 2017;8(2):659-669.

  19. Lu J, Wong RN, Zhang L, Wong RY, Ng TB, Lee KF, Zhang YB, Lao LX, Liu JY, Sze SC. Comparative Analysis of Proteins with Stimulating Activity on Ovarian Estradiol Biosynthesis from Four Different Dioscorea Species in vitro Using Both Phenotypic and Target-based Approaches: Implication for Treating Menopause. Appl Biochem Biotechnol. Sep 2016;180(1):79-93.

  20. Tikhonova MA, Yu CH, Kolosova NG, Gerlinskaya LA, Maslennikova SO, Yudina AV, Amstislavskaya TG, Ho YJ. Comparison of behavioral and biochemical deficits in rats with hereditary defined or D-galactose-induced accelerated senescence: evaluating the protective effects of diosgenin. Pharmacol Biochem Behav. May 2014;120:7-16.

  21. Wu GC, Lin SY, Liang HJ, Hou WC. 135-Day Interventions of Yam Dioscorin and the Dipeptide Asn-Trp (NW) to Reduce Weight Gains and Improve Impaired Glucose Tolerances in High-Fat Diet-Induced C57BL/6 Mice. J Agric Food Chem. Jan 24 2018;66(3):645-652.

  22. Tohda C, Yang X, Matsui M, Inada Y, Kadomoto E, Nakada S. Watari H, Shibahara N. Diosgenin-Rich Yam Extract Enhances Cognitive Function: A Placebo-Controlled, Randomized, Double-Blind, Crossover Study of Healthy Adults. Nutrients. Oct 24 2017;9(10).

  23. Powers CN, Setzer WN. A molecular docking study of phytochemical estrogen mimics from dietary herbal supplements. In Silico Pharmacol. Mar 22 2015;3:4.