Bioidentical Hormones – Understanding the Basics

By Christiane Northrup, MD.

There seems to be a lot of confusion around the definition of “natural” versus “bioidentical” versus “synthetic” hormones. One thing to remember when making this distinction is that “bioidentical” refers to the shape of the molecule itself rather than the source of the hormone. By this, I mean that hormones can be marketed as “natural” or “plant-based,” yet not come near to being “bioidentical” to native human female hormones or performing as such in the body. Examples of this are the numerous proprietary HRT options being marketed as “plant-based” and “natural,” as well as purely yam-based creams.

Our bodies are literally swimming in hormones that act somewhat analogous to keys in a lock, or pieces to a puzzle. Though this analogy presents a less than complete picture, it can be helpful toward a basic understanding of their action. The puzzle to which I refer makes up the big picture of who we are as human beings and how we operate. When we take in hormonal replacement therapy that doesn’t fit the original design that our cells have evolved to recognize, the end result simply may not feel or act quite right. Hence all those side effects, ranging from annoying and uncomfortable to downright dangerous.

Many pharmaceutical companies are capitalizing on women’s quest for “natural” hormone replacement therapy by marketing proprietary hormone products that are “plant-based.” Yes, many of these hormonal molecules may have been derived from plant sources, but no, the molecules themselves do not always match those found in human females. Moreover, they are often not effectively converted or used in the body and sometimes have actions that are more deleterious than the symptoms they purport to quell or stave off.

Our hormones are comprised of a solid steroid base (yes—cholesterol!), decorated with “arms,” “legs,” and “tails” pinned on here and there. These attachments are what turn hormones into specialized molecules, allowing them to plug in to receptor molecules throughout the body, turning on and off much of the cellular behavior that makes us tick.

Pretty slick! Bioidentical hormones are those whose biochemical structure exactly duplicates those found “naturally” in the human body—that is, the ones whose structure has evolved for millenia. Why mess with a good thing?

True Natural Hormones

The molecules naturally produced in the human female body for which we most often seek replacement include the following: a) the three basic types of estrogen: estrone (E1), estradiol (E2), and estriol (E3); b) progesterone; c) testosterone and d) DHEA, an adrenal precursor to testosterone. These truly “natural” hormones are available by prescription (or, in the case of progesterone and DHEA, over-the-counter in low doses), and can also be readily titrated to a woman’s individual needs. Though many health care practitioners are still not trained in prescribing them, the opportunity is there for them to learn, and health care providers are becoming increasingly aware of their patients’ preferences.

Bear in mind that most of the mainstream studies have been performed on conventional HRT. In addition, pharmaceutical companies cannot take out a patent on what the majority of human women make effortlessly on a daily basis and, therefore, cannot generate large sums of money by packaging and selling them. This may explain why women are commonly offered prescriptions for nonbioidentical forms of HRT, while their efforts to obtain a prescription for bioidentical HRT can be met with varying degrees of skepticism. On the other hand, unique delivery systems for HRT are patentable, and for this reason options for HRT delivered via transdermal skin patches abound, some of which are bioidentical. Examples include many of the estrogen patches, including Vivelle, Estraderm, and Climara.

Most women know that Premarin, Prempro, and Provera are not bioidentical. My colleague Dr. Joel Hargrove says, “Premarin is a natural hormone—if your native food is hay!” (It’s made from conjugated mare urine.) Provera was developed as a substitute for bioidentical progesterone (the kind found in the human female body) because you cannot patent a naturally-occurring hormone! Prempro is a combination of Premarin and Provera.

If you are in doubt as to whether a particular product offered to you by prescription is natural, check the label—if it lists anything other than the above ingredients, including “esterified estrogens,” “progestins,” or “progestogens,” the product is essentially not bioidentical. You can also go to your library and look the product up in the most up-to-date Physician’s Desk Reference, or try plugging it into your favorite search engine on the Internet—many proprietary products even have their own site.

Many people have written to me to express their confusion about the use of progesterone creams, particularly regarding the efficacy of yam-based or other plant-based creams.

Unlike soy and flax, for example, which contain plant-based estrogens (phytoestrogens) that are adaptogenic and converted into utilizable forms in the body, wild yam (Dioscorea barbasco) cannot be converted into progesterone in the body.

The conversion can occur in a laboratory setting, however, and therefore, wild yam is sometimes used to synthesize the progesterone found in progesterone creams. The cream may technically be yam-based, but its active ingredient is not the wild yam itself but the USP progesterone that has been added. For this reason, while the body may absorb wild yam extract through the skin, which may then confer mild effects on menopausal symptoms, results of research on oral and topical applications of wild yam extract have not detected a significant change in progesterone levels in the blood.

If you want the beneficial effects of bioidentical progesterone, make sure the ingredients on the label include United States Pharmacopoeia (U.S.P.) progesterone. U.S.P. progesterone is available in over-the-counter 2% creams as well as by prescription. Choices for prescription-based bioidentical progesterone include Crinone Vaginal Gel in 4% or 8% concentration, or in an oral micronized form such as Prometrium capsules.

Talking with Your Practitioner

I receive letters almost daily from women who have taken the initiative to offer their health care providers information on the natural approach to HRT, some with great success and others meeting with failure. In any case, it’s your body, and therefore it’s worth a try.

Here are the salient points to know and to share with your practitioner:

•    Our native human hormones can be synthesized in laboratories to exactly duplicate those found in our bodies.
•    Bioidentical HRT has been prescribed by doctors for many years and is readily available through formulary pharmacies.
•    Bioidentical HRT is easily titrated to suit women’s individual needs, is readily absorbed and utilized, and is safe and effective.
•    Bioidentical hormones are the ones we want to use as replacement therapy, if and when we decide they are necessary.

Recommended Resources and Reading:

Many physicians and formulary pharmacists work in partnership with their patients to provide individualized hormone-replacement solutions. Ask your physician about this kind of customized care; he or she can call a local formulary pharmacy to consult with a knowledgeable pharmacist.

For more information read:

•    The Wisdom of Menopause, by Christiane Northrup, M.D., Chapter 5, “Hormone Replacement: An Individual Choice”
•    Women’s Bodies, Women’s Wisdom, by Christiane Northrup, M.D., Chapter 14, “Menopause”

To locate a pharmacy that provides individualized prescriptions, contact:

•    International Academy of Compounding Pharmacists (IACP) –  IACP (formerly known as Professionals and Patients for Customized Care, or P2C2) is a nonprofit organization made up of more than 1,300 compounding pharmacists nationwide. The IACP website has a locator feature that can help you find a compounding pharmacy in your area.
•    American Hormones, Inc. This compounding pharmacy was founded by Erika T. Schwartz, M.D., renowned expert in the field of natural hormones. American Hormones offers high-quality pharmaceutical-grade hormones shipped nationwide and internationally. The website has extensive information on bioidentical hormones.

For additional information on individualized hormone therapy, contact the Natural Woman Institute. The Natural Woman Institute was founded by Christine Conrad, author of A Woman’s Guide to Natural Hormones (New York: Perigee, 2000). NWI maintains a database of physicians and health practitioners nationwide who prescribe natural, bioidentical hormones.

This information is not intended to treat, diagnose, cure, or prevent any disease. All material in this article is provided for educational purposes only. Always seek the advice of your physician or other qualified health care provider with any questions you have regarding a medical condition, and before undertaking any diet, exercise, or other health program.

© Christiane Northrup, Inc. All rights reserved. Reproduction in whole or in part without permission is prohibited.


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