The wild yam plant (a different plant from the sweet potato/yam) has natural progesterone in it. That is the active ingredient that makes it so helpful to women’s issues. Not only does our estrogen drop at menopause, but also progesterone. There was a physician, the late John Lee, MD, who was the first person to research and write about this. Surely herbalists knew about the power of the wild yam for centuries, but our folk knowledge has been lost in the last century.