The term bio-identical has basically become a catch all phrase for anything that is not a synthetic hormone. It is commonly applied to look-alike molecules derived from “natural” plants that are substituted for our own endogenously-produced hormone molecules. So “natural” or bioidentical hormones are made in a laboratory by converting natural plant compounds from wild yams and soybeans into chemical molecules identical to those made in the human body for 17-beta estradiol, progesterone, or testosterone.

These sources of plant hormones mimic the chemical structure of hormones produced by the human body.  The premise is that the body can’t distinguish created bio-identical hormones from the ones the female ovaries produce naturally. 

Bio-identicals are available in standardized tablets, patches, compounded creams, gels and injectable prescriptions.