Bioidentical versus non-bioidentical (bio-similar) hormones

Many men and women seeking hormone replacement therapy from anti-aging doctors like myself ask about the safety of the hormones that we prescribe.

The reason for this concern, often mentioned to them by their family doctors, is that the Women’s Health Initiative, the Nurses Study and other studies show that “hormones” were “dangerous,” because they slightly increased cancer and other disease risks.

These studies were done using the drug Prempro, a combination Premarin and Provera. Premarin is bio-similar to the human hormone estrone. Provera is biosimilar to the human hormone progesterone. Neither is bioidentical. Premarin is made from the horse hormones equilin and equilenin. These two compounds differ slightly but significantly from the human estrogen called estrone. These differences, and the way it is processed by the human liver, result in the body receiving a foreign chemical that is different from what the ovaries used to make. These differences cause it to have a unwanted stimulatory effect on the metabolism of these compounds. This can actually increase the possibility of DNA damage within the nuclei of our cells which can contribute to cancer. The same thing was true with Provera, which was shown in a separate arm of the WHI study to have even more negative effects on cancer then Premarin. Provera is a progestin, which is not the same as progesterone. Many if not most traditionally trained MDs are confused about the differences of progestins versus progesterone. This is why you might hear the statement from magazines, newspapers or your physicians that “hormones” are dangerous. To be accurate, what they should be saying is that Provera or Prempro are potentially dangerous. But this is not what patients hear, adding to their confusion.

The other meaning of the world bioidentical is how the hormones are delivered to the body. In general, with the exception of oral progesterone which is very safe, bioidentical hormones are delivered through the skin or mucous membranes or even implanted in the body. By avoiding processing by the stomach and later the liver, hormones delivered by a cream or gel or implant can enter the bloodstream directly and travel to the target areas where they are needed before they are altered chemically by the liver. This is exactly what happens when the ovaries and the testes release hormones-they enter the bloodstream directly and travel throughout the body before they reach the liver. In this way the cells of the body receive the hormone unchanged from what is applied to the skin or elsewhere. This is very important and further renders these hormones much safer then oral forms.

Anti-aging physicians educate their patients to understand the difference between bioidentical and biosimilar hormones. By doing this they understand that some of the negative studies on commercial hormones are not applicable to the safe and beneficial bioidentical hormones are we prescribe to them (and take ourselves)! We also can provide to our patients published clinical studies documenting the safety of bioidentical hormones.