“Bioidentical” is a term used to indicate that a product is made to be chemically identical to the hormone your body produces. However, the ingredients of a bioidentical product, whether in a compounded version or an FDA-approved product, are all manufactured in a lab.
So, is bioidentical more natural?
No. No menopausal hormone therapy product comes directly from nature or is “natural” with one exception — a type of estrogen called conjugated equine estrogen (CEE). CEE comes from a pregnant horse’s urine. So it is, in fact, made in nature. The idea of bioidentical products being “natural” menopausal hormone therapy products has long been associated with compounded products but it is a misconception.
Are bioidentical products safer?
Not necessarily. While there is something logically appealing and mentally comforting about products that are more similar to what our body makes, in the case of estrogen there are no studies demonstrating that the bioidentical form of estrogen (i.e., 17-beta-estradiol) is safer or more effective than other estrogen-like products such as Premarin® (CEE). As Dr. Marcie Richardson, The Director of the Menopause Consultation Service at Atrius Heath, put it: “While there is an appealing, seemingly intuitive logic that a bioidentical molecule, more similar to the ones our bodies produce would be safer, there haven’t yet been studies that support this idea for estrogens.” Dr. Nanette Santoro, Chair of Obstetrics and Gynecology at the University of Colorado and a leading researcher on midlife women’s health underscored this point: “Based on the research that has been done to date, an estrogen is an estrogen is an estrogen, bioidentical or not.” The estrogen receptor is stimulated by all estrogens and that is how estrogen effects play out in the body.
Progesterone may be a different story. In 1995, a randomized-controlled trial compared different estrogen and progestogen (products that have progesterone-like effects) combinations on markers of cardiovascular health in 875 postmenopausal women. The trial demonstrated that progesterone (Progesterone USP), the form identical to the one your body makes had a more favorable impact on cholesterol and was better tolerated than Provera® (medroxyprogesterone acetate) — a progestin, one created to act like progesterone.
If you look at the molecular structures of progesterone (the one your body makes) and a progestin (made to act like progesterone) you will notice they are different.
In terms of comparing safety, there has not yet been a randomized trial that demonstrates that progesterone is safer than progestins. However, recent reviews of observational studies have raised the question of whether progesterone is safer with respect to breast cancer risk than progestins like Provera (medroxyprogesterone acetate).1,2
For those reading closely, you’ll note the use of three very similar words: progesterone, progestogen and progestins. Briefly, progesterone is the hormone your body produces, and progestogen is used to describe all products that have progesterone-like effects, including progestins. More on that here.
1. Asi N, Mohammed K, Haydour Q, et al. Progesterone vs. synthetic progestins and the risk of breast cancer: a systematic review and meta-analysis. Syst Rev. 2016;5(1):121. Published 2016 Jul 26. doi:10.1186/s13643-016-0294-5
2. Stute P, Wildt L, Neulen J. The impact of micronized progesterone on breast cancer risk: a systematic review. Climacteric. 2018;21(2):111-122. doi:10.1080/13697137.2017.1421925
