Bio-identical hormones are supplemental hormones that are exactly identical to hormones found in the human body. This is different than conventional HRT which, in order to be patented, were synthesised to be different from, and stronger than, human hormones. It is because conventional HRT differs molecularly from human hormones that conventional HRT is a risk for cancer.
There are many different types of bio-identical hormones. They are not just one thing. Each one: oestrogen, progesterone, DHEA must be considered individually.
For a current look at research into BHRT see
