Wild yam contains natural progesterone and may increase production of it in the body.
– 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(2):144-150.

Significantly reduced serum lipid peroxidation, lowered serum triglycerides, phospholipid and increased HDL levels. Both DHEA and the steroid yam extract, dioscorea, have significant activities as antioxidant to modify serum lipid levels.

– Araghiniknam M, Chung S, Nelson-White T, et al. — Antioxidant activity of Dioscorea and dehydroepiandrosterone (DHEA) in older humans. — Life Sciences 1996;59:L147-L157.

Use is not recommended if you are preganant or nursing.

In conclusion, there was no acute reno- or hepato-toxicity associated with administration of wild yam (D. villosa). However, there was an increase in fibrosis in the kidneys and in inflammation in livers of rats consuming D. villosa for 28 days. Long term supplementation with D. villosa may be best avoided, especially in people with compromised renal function and in those who need to take other drugs which may alter kidney function.
– Food Chem Toxicol. 2008 Sep;46(9):3122-31. Epub 2008 Jul 10. — Dioscorea villosa (wild yam) induces chronic kidney injury via pro-fibrotic pathways. — Wojcikowski K, Wohlmuth H, Johnson DW, Gobe G.