Various species of wild yam grow throughout North and Central America and Asia. Traditionally, this herb has been used as a treatment for indigestion, coughs, morning sickness, gallbladder pain, menstrual cramps, joint pain, and nerve pain.1 The main use of wild yam in the United States today, however, is based on a fundamental misconception: that it contains women's hormones, such as progesterone and DHEA.
In reality, there is no progesterone, DHEA, or any other hormone in wild yam, nor does wild yam contain any substances that have progesterone-like or estrogen-like effects.2
To explain this widespread misunderstanding, we have to go back a number of years. When progesterone was first discovered, it was very expensive to produce. The first methods involved direct extraction of progesterone from cow ovaries, a process that required 50,000 cows to yield 20 mg of purified hormone! 3 Other hormones like estrogen and DHEA were also difficult to manufacture. Although doctors wanted to experiment with prescribing these treatments as medicine until a simpler production method could be developed, it simply was not feasible.
The race to discover a more economical source of hormones was won by a scientist/businessman named Russell Marker. In the 1940s, he perfected a method of synthesizing progesterone from a constituent of wild yam called diosgenin. This process involves several chemical transformations carried out in the laboratory.
Marker focused his attention on two species of yam found in Mexico, Dioscorea macrostachya and Dioscorea barabasco, the latter of which is richer in diosgenin, while the former is much easier to harvest in the wild. He formed a manufacturing company in Mexico that produced progesterone and DHEA from these raw materials.
Unfortunately, corporate competition and difficult labor conditions eventually forced him to close his plant. But Marker's method of synthesizing progesterone continued to be used, bringing the price down drastically and helping to pave the way for the modern birth control pill. Progesterone continued to be manufactured from wild yam for decades, until a cheaper source of raw material was found in cultivated soybeans.
But neither soybeans nor wild yam contain progesterone. They only contain chemicals that chemists can use as a starting point to manufacture progesterone. However, just because chemists can make progesterone out of diosgenin does not mean that the body can do the same. Actually, it is very unlikely because the steps used by chemists to carry out this conversion do not even remotely resemble natural processes. Thus, any product that claims to contain "natural progesterone from wild yam" is misleading.
Studies involving cells in a test tube have found that wild yam does not act like estrogen or progesterone.2 Furthermore, in a double-blind, placebo-controlled study of 23 women with symptoms of menopause, use of wild yam did not reduce hot flashes nor raise levels of progesterone or estrogen in the body.4 On the other hand, a study involving 50 menopausal women found that the yam species Diascorea alata (12 mg sachet twice daily for 12 months) was more effective at relieving menopausal symptoms than placebo.5 The researchers did not explain how this type of yam could produce such an effect.
An interesting point is that some wild yam products do contain progesterone. Are we contradicting ourselves? Not at all. Manufacturers add synthetic progesterone to these creams. There may be a value to taking progesterone in cream form, but the wild yam part of the product seems to be misleading.
1. Tierra M. The Way of Herbs: Fully Updated—With The Latest Developments in Herbal Science. New York, NY: Pocket Books; 1998:246.
2. Zava DT, Dollbaum CM, Blen M. Estrogen and progestin bioactivity of foods, herbs, and spices. Proc Soc Exp Biol Med. 1998;217:369-378.
3. Tyler VE, Brady LR, Robbers JE. Pharmacognosy. 8th ed. Philadelphia, PA: Lea & Febiger; 1981.
4. 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. 2001;4:144-150.
5. Hsu CC, Kuo HC, Chang SY, Wu TC, Huang KE. The assessment of efficacy of Diascorea alata for menopausal symptom treatment in Taiwanese women. Climacteric. 2011;14(1):132-139.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015