Bioidentical hormones are made in a laboratory from plants such as wild yam, cactus, and soy. The structure and function of these hormones are identical to those made by the human body. In the 1950s, scientists identified a phytoestrogen known as diosgenin in plant roots that could be chemically converted to hormones such as estrogen, progesterone, testosterone, and DHEA. Compounding pharmacies use bioidentical hormone preparations to tailor dosages for individual patients.