What are Bioidentical Hormones?

Simply put, they are hormones that have the exact same molecular structure as the hormones found in the woman’s body prior to menopause. They have individual names that you should know: estradiol, progesterone, and testosterone. Other less commonly used bioidentical hormones are estrone and estriol (two weaker metabolites of estradiol, the principal estrogen of the ovary), dehydroepiandrosterone (DHEA) and melatonin.

The non-bioidentical hormones which have been offered as substitutes for these are:

For estradiol: Premarin®, conjugated estrogens, estradiol valerate, ethinyl estradiol, etc.
For progesterone: medroxyprogesterone acetate (MPA) aka Provera®, norethindrone acetate, drosperinone, levonorgestrel, etc.
For testosterone: methyl testosterone, tibolone, etc.

Each of these substitutes for the real thing has similar physiological activity in the tissues looked at (bone, breast, uterus) to the bioidentical hormone in a woman’s body, but NOT IDENTICAL IN EVERY TISSUE. Therein lies the crux of the problem with the bioidentical substitutes. The bioidentical hormones are active in virtually every organ system in the body. This means that through millions of years of natural selection, the human body has evolved to utilize each of them for specific purposes throughout the body. In contrast, drugs are designed to achieve a particular result in a certain tissue. They are tested to see if that tissue is affected in the desired way: did the artery relax and lower blood pressure, did the bone get denser, did the neuron stop firing and the mind get calmer, did the hot flashes stop. Any other effect that the drug has in another organ system is deemed a side effect. Side effects are not investigated as extensively as the intended effect; they are merely noted. If they are too severe or happen in too many people, the drug will not be approved, even if the effect in the target tissue is good. Often, however, these side effects are very subtle or occur gradually over years and therefore are missed. Or, the correct instruments are not utilized in the approval process studies to detect them.

But when a woman loses her estradiol, progesterone, and testosterone we are not replacing them to achieve a particular effect in one or two organ systems; we are replacing them to recreate the effects they have in all tissues.

It seems silly, in a way, because why would anyone want to replace the hormones that decline at menopause with anything other than the exact same thing? But the hubris of modern medicine combined with the dictates of the patent system have led pharmaceutical companies, in league with academic researchers, to create hormones that are slightly altered versions of the bioidentical hormones.

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