17-beta estradiol, the most biologically active;
estrone, a derivative of estradiol and
the second most dominant estrogen; and
estriol, a very short-acting estrogen and
the least biologically active.
The first misconception is that US Food and
Drug Administration (FDA)-regulated drugs are not bioidentical. This is wrong. A long list of FDA-approved hormone products contain 17-beta estradiol and
, therefore, are bioidentical.