It has been hypothesized that wild yam (Dioscorea villosa and other Dioscorea species) possesses dehydroepiandrosterone (DHEA)-like properties and acts as a precursor to human sex hormones such as estrogen and progesterone. Based on this proposed mechanism, extracts of the plant have been used to treat painful menstruation, hot flashes, and headaches associated with menopause. However, these uses are based on a misconception that wild yam contains hormones or hormonal precursors - largely due to the historical fact that progesterone, androgens, and cortisone were chemically manufactured from Mexican wild yam in the 1960s. It is unlikely that this chemical conversion to progesterone occurs in the human body. The hormonal activity of some topical wild yam preparations has been attributed to adulteration with synthetic progesterone by manufacturers, although there is limited evidence in this area.
The effects of the wild yam saponin constituent "diosgenin" on lipid metabolism are well documented in animal models and are possibly due to impaired intestinal cholesterol absorption. However, its purported hypocholesterolemic effect in humans and the feasibility of long-term use warrant further investigation.
There are few reported contraindications to the use of wild yam in adults. However, there are no reliable safety or toxicity studies during pregnancy, lactation, or childhood.
Atlantic yam, barbasco, batata silvestre, black yam, China root, colic root, devil's bones, Dioscorea, Dioscorea barbasco, Dioscorea hypoglauca, Dioscorea macrostachya, Dioscorea opposita, Dioscorea villosa, Dioscoreae (family), diosgenin, Mexican yam, natural DHEA, phytoestrogen, potassium, rheumatism root, shan yao, white yam, wild yam root, yam, yellow yam, yuma.
Note: "Yams" sold in the supermarket are members of the sweet potato family and are not true yams.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Animal studies have shown that wild yam can reduce the absorption of cholesterol from the gut. Early studies in humans have shown changes in the levels of certain sub-types of cholesterol, including decreases in low-density lipoprotein (LDL, or "bad cholesterol") and triglycerides and increases in high-density lipoprotein (HDL, or "good cholesterol"). However, no changes in the total amount of blood cholesterol have been found. More studies are needed in this area.
Most studies have not shown a benefit from wild yam given by mouth or used as a vaginal cream in reducing menopausal symptoms. However, replacing two thirds of staple food with yam for 30 days was shown to improve the status of sex hormones, lipids, and antioxidants in a recent study in postmenopausal women. The authors suggest that these effects might reduce the risk of breast cancer and cardiovascular diseases in postmenopausal women. Further research is needed before a recommendation can be made.
Hormonal properties (to mimic estrogen, progesterone, or DHEA)
Despite popular belief, no natural progestins, estrogens, or other reproductive hormones are found in wild yam. Its active ingredient, diosgenin, is not converted to hormones in the human body. Artificial progesterone has been added to some wild yam products. The belief that there are hormones in wild yam may be due to the historical fact that progesterone, androgens, and cortisone were chemically manufactured from Mexican wild yam in the 1960s.