Bio-identical hormones are plant-based hormones that have the same molecular structure as those naturally occurring in men and women
They are produced in the laboratory, usually from soy or wild yam. They could be used as a replacement for a variety of human hormones: estrogen, progesterone, testosterone, thyroid hormone, DHEA, etc.
The term ‘Natural Hormones’ is often interpreted as being synonymous with bio-identical hormones, but that is not always the case. For example, Premarin is an estrogen that comes from horses, so it is natural, but it is not chemically identical to the human estrogens, and therefore, not bio-identical.
The term ‘Synthetic Hormones’ is interpreted by most as non-bio-identical hormones, which is also not always the case. Bio-identical hormones derived from plants are also synthetic because they are created in a laboratory.
Also, some plant-derived (“natural”), synthetic hormones (because they are made in a lab) are not always bioidentical, so a plant origin does not always mean bio-identical either.
The terms ‘bio-identical’ and ‘non bio-identical’ are the best to use when it comes to hormone replacement as they are the most accurate. This subject could be quite confusing because of the intentional or unintentional use of these terms interchangeably by the big pharmaceutical companies promoting their products. On the other hand, Compounded Hormone replacement products are always bio-identical. The use of commercial or compounded products have pros and cons which you should discuss with your physician.