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What Are Bioidentical Hormones?


Updated April 07, 2008

Question: What Are Bioidentical Hormones?
Bioidentical hormones are promoted as a "natural" alternative to conventional hormone replacement therapy. But exactly what is a bioidentical hormone? And are they safer than other prescribed hormones? Whether to use menopause hormone therapy is a complex decision, and bioidenticals add another layer to sort through before deciding whether hormones are for you.

The term “bioidentical hormones” usually refers to estrogen and progesterone that are chemically identical to what your body produces. Many hormones are synthesized in ways that slightly alter their chemical makeup. Therefore, it’s possible that they work differently in the body than those produced naturally in your system. We don’t know that manufactured hormones which are different than our own do work differently, we just know that they may work differently.

Often when people refer to “natural” or “bioidentical” hormone therapy they are referring to individualized hormones that are made in compounding pharmacies. These pharmacies are not regulated to assure that doses are consistent and that quality is reliable, therefore there can be variations in these formulas.

Bioidentical hormones have been promoted as a “safe” alternative to prescription hormones, and one that preserves youth and health well beyond menopause. This is where sorting out the facts from the hype gets a little sticky. Here are some of the issues to consider:

  • Definition of “bioidentical.” There is no official, medical definition of bioidentical. It usually refers to a chemical or compound that has the same molecular structure as those chemicals and compounds found in nature. This is confusing in the case of hormone therapy because the terms “natural” or “compounded” are used interchangeably with “bioidentical” when referring to hormones.

  • The Women's Health Initiative (WHI) study. This study was undertaken to show the health impact of taking menopause hormone therapy. Part way through the study, it was clear that women taking certain combinations of hormone therapy were actually at more, not less, risk for some conditions like heart disease, stroke, blood clots and breast cancer. Thousands of women stopped taking hormone therapy and began to look for safer alternatives.

  • FDA approval. The Food and Drug Administration is responsible for overseeing safety and effectiveness of drugs. Hormones that are prepared by compounding pharmacies or produced as dietary supplements are not regulated by the FDA, and therefore there is little scientific information on their safety or effectiveness.

  • The menopause cohort. A lot of women are heading into menopause over the next decade. About 4,000 additional women enter menopause each day. And just as the millions of baby boomer women changed the landscape for sexuality in the 60s, we will probably have enormous impact on how the culture views menopause from here on in. Not only are we accustomed to participating in our health care, we are also a huge market for products that help us as we age –- a fact not lost on drug companies, whether it is the ones cashing in on bioidenticals or pharmaceutical companies that produce medications for age-related conditions. We are a great big customer, worth courting.

  • Health consciousness. Women have never been more health aware than they are now. Sexual health is something we think about and care about. Hormone issues have been part of our life context in the form of DES exposures from our moms, the availability of the first birth control pills, recognizing the impact of chemicals on the fetus during pregnancy, and even the naming of premenstrual syndrome. We understand that hormones are powerful chemicals and that reproductive decisions have health consequences.

The combination of these elements adds up to the perfect storm of millions of women who want support in dealing with menopause, scientific evidence that the “old” way of prescribing hormone replacement therapy could be risky, and promises of “natural” relief of our symptoms with bioidentical hormones.

Are Bioidentical Hormones Better For You?

It’s hard to say for certain whether bioidentical hormones have a lower risk than other hormone formulations. The lion’s share of research has been done on prescription hormones that are not bioidentical, so we have very little information on whether one or the other is more effective, and almost no information on which versions are higher risk. While it is a logical thought that the bioidentical hormones might be lower risk because your body would not react negatively to them, we don’t yet have evidence to support this. Until there is evidence of safety, it’s best to assume that they carry similar risks to the hormones that have been studied.

Bioidentical hormones have had a lot of press as celebrities get on the bandwagon and tout them as magical youth elixirs. Don’t lose sight of the fact that these celebrities also have the money for cosmetic surgery, expensive skin treatments and a covey of trainers and attendants to help them stay young and well. The average menopausal woman does not have the money and time to spend tending to her body that celebrities do, and yet we somehow think that we should look as young and gorgeous as women who spend thousands on their appearance. Is it the hormones or the face lift that makes a movie star look younger?

Is There Safe Middle Ground?

If you are a good candidate for menopause hormone therapy because of your symptoms or risk factors and you are interested in trying bioidentical hormones, talk to your doctor. There are FDA approved bioidentical versions of estrogen and progesterone. These bioidentical formulations have been tested and approved for menopause hormone therapy. Dosage is consistent and quality is dependable in these products, and they can be prescribed through a conventional pharmacy. They are more likely to be covered by insurance than compounded products.

Finding effective treatments for menopause symptoms that disrupt your life can be hard work. Bioidentical hormones my work well, but remember that they are still hormones -- however "natural" they are in chemical makeup. They will have the benefits of hormones, but they will also have the risks. So make choices carefully and discuss all the options with your medical provider before deciding.


North American Menopause Society (NAMS), Resource Page on Bioidentical Hormones. Retrieved 26 Mar, 2008.

Endocrine Society, Position Statement on Bioidentical Hormones. Oct, 2006. Retrieved 26 Mar, 2008.

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