The Hollywood actress Susan Sommers recently scored a bestselling book on menopause in which she, amongst other things, very strongly propagated the use of bioidentical and/or natural hormones. Because of the popularity of this book, it is important to discuss this issue a little bit more in detail.

Before discussing this topic further, we, however, require a few definitions: So-called natural hormones are for humans not necessarily natural because their usual sources are animals. When processed in preparation for human consumption, they usually undergo only very few chemical changes and they, therefore, are not identical in their chemical composition to their human counterparts.

In contrast, bioidentical hormones are usually derived from plant precursors, which are chemically “rebuilt” to mimic the exact chemical structure of the human hormone. Such produced estrogens usually started out from soy building blocks, while pro gesterones derive from yams.

A third form of hormones are so-called synthetic hormones which are entirely formulated and built in a pharmacological laboratory. Many hormones, of all three varieties, have been approved by the FDA and, they, in general, have the same risks as well as benefits. This is important to note because the public is often under the wrong impression that natural and/or bioequivalent hormones are “healthier’ and “better.”

Pharmacists sometimes compound hormones. This means that they, at times, create combinations of various hormones, mixing natural with bioidentical and/or synthetic products. Such compounded hormones are not FDA-approved and, like over-the- counter supplements, they may not be consistent in quality and quantity.

Surveys have shown that most women (especially after Susan Sommer’s book) believe that natural and/or bioidentical hormones are better. Indeed, a study suggested that 71% of women believe that such hormones have significantly fewer (or even no) risks, 69% that they have fewer side effects and 62% believe that they are at least equal, or even superior in managing menopausal symptoms (Adams and Cannel, Menopause 2001; 8:433-40). Unfortunately, there are absolutely no data to support such assumptions. Indeed, all available data suggest the opposite: Since all of these hormones act through the same receptors on cells, their biological effects can be expected, and appear to be, identical.