The Truth About Bioidentical Hormones

by Martica Heaner, MA, PhD on Apr 22, 2010


A lot of middle-aged women are taking a “natural” hormonal supplement that isn’t so natural (or especially safe) after all. Here’s what you should know about bioidentical hormone therapy.

Many of your Baby Boomer female clients or class members may be taking—or thinking about taking—bioidentical hormones. Fantastic claims are often made about these supposedly “natural” hormones. Not only are they said to relieve the symptoms of menopause, but they are often purported to cure a host of diseases and even to increase longevity (Boothby & Doering 2008).

Not so fast, say medical organizations such as the American College of Obstetricians and Gynecologists (ACOG), the American Medical Association (AMA), the Endocrine Society and the American Association of Clinical Endocrinologists (AACE): these “bioidentical” hormones have not yet been proven to be effective or safe, even if they are often marketed as being risk-free and superior to conventional hormones (U.S. Food and Drug Administration [FDA] 2008a).

Although doling out personalized nutrition and medical advice is beyond your purview as a fitness trainer, it’s useful to know which medications and/or supplements your clients are taking and what the possible effects on their health might be.

Why Do Women Take Hormones?

The reason why many women turn to any type of hormone therapy is to alleviate the unpleasant symptoms associated with midlife changes. Starting in a woman’s mid-40s to early 50s, estrogen production decreases, and shifts occur in the levels of other sex hormones, such as progesterone, leading to the permanent cessation of the menstrual cycle, known as menopause. In some women, symptoms of this hormonal shift (which can start with perimenopause and continue until postmenopause) may include hot flashes (breaking out in a severe sweat), restless sleep, low libido, vaginal dryness, memory loss and increased emotionality. During this life cycle, other physiological changes occur, including loss of bone mass and an increase in abdominal fat (Cirigliano 2007).

The Backlash to Conventional Hormone Therapy

Typically, women have sought hormone replacement therapy (HRT) to compensate for lower levels of estrogen—and to stave off unpleasant symptoms. Dosing up on various forms of FDA-approved HRT has proven efficacious. Bone mass is maintained, or even improved, while symptoms such as hot flashes or vaginal dryness are ameliorated (Cirigliano 2007).

However, the shocking results in 2002 from a large research trial known as the Women’s Health Initiative (WHI) scared many women off conventional HRT regimens. Researchers decided to cease one of the studies, called the Estrogen Plus Progestin Study, after female participants who had been taking hormone pills for an average of 5.6 years showed increased risks of both cardiovascular disease and breast cancer, compared with other women taking a placebo (WHI 2002). Although there were improvements in bone mass and menopausal symptoms, the women taking hormones experienced a 29% increase in heart attacks, a 41% increase in strokes and nearly double the risk of blood clots (WHI 2002). Many women who heard about the WHI study stopped taking their prescribed hormones, creating a greater demand for a more natural and/or safer alternative (Cirigliano 2007).

Enter bioidentical hormones, famously promoted by former 1970s sitcom star Suzanne Somers. In several books and on internationally televised shows, Somers alleged that conventional HRT was dangerous, while she hyped the benefits (and downplayed the risks) of bioidentical hormone therapy. When medical experts pointed to the lack of research-based evidence to support any claims that bioidenticals were superior to conventional HRT, a controversy arose (Endocrine Society 2006; Kuehn 2008; FDA 2008b).

What Are Bioidentical Hormones?

Bioidentical hormones are compounded versions of various forms of estrogen and progesterone, and sometimes testosterone. There are different forms and proportions of estrogen and progesterone in the human body, and these are also present in both conventional and bioidentical hormone therapies. Bioidentical formulations are created by compounding pharmacists (see the sidebar “What Is a Compounded Drug?”), who purportedly personalize products to meet women’s unique hormone profiles. In contrast, FDA-approved hormone therapies must adhere to standardized dosages and are strictly regulated by the agency to ensure expected potency (ACOG 2005).

Bioidenticals are touted as being identical in chemical structure to endogenous hormones (i.e., those made in the human body) and therefore safer than conventional HRT. (Conventional hormone therapies contain synthetic analogs, although they may include “bioidentical” hormone forms as well.) Advocates of bioidenticals say that their structure improves the hormones’ ability to bind to receptors in the body, making therapy less risky and better tolerated. While different forms of various hormones do have different binding capacities, this distinctive aspect alone has not been proven to affect the severity of the side effects that women may experience (Boothby & Doering 2008; Cirigliano 2007).

Unlike conventional HRT, bioidentical hormones are not subject to FDA regulations and approval, because they are compounded by pharmacists, a category that is currently FDA exempt. (The term bioidentical hormone therapy is “a marketing term not recognized by the FDA” [FDA 2008a]). Even though bioidenticals are not FDA approved, how they are marketed is subject to strict guidelines. For example, only FDA-approved drugs can claim to treat, prevent or cure a disease or medical condition, because the agency’s approval signifies that extensive research has been conducted to guarantee the safety and efficacy of a drug at established doses. (Note that “safety” does not mean that a drug is without side effects, only that the benefits outweigh the risks.)

Are Bioidenticals More Natural Than HRT?

Bioidenticals are marketed as “natural” hormones. They are derived from plant sources, whereas synthetic hormones come from animal sources. However, whether a plant or an animal derivative is more “natural” for the human body is up for debate. Both bioidenticals and conventional hormones are chemically modified into forms that can bind to receptors in the human body.

Often, consumers infer that because bioidenticals are plant based, they are not real drugs. But make no mistake: “These are actually drugs,” says James H. Liu, MD, chairman of the department of obstetrics and gynecology at University Hospitals Case Medical Center in Cleveland. “You can’t buy them over the counter; they must be prescribed.”

Are Biodienticals More Effective Than HRT?

Bioidenticals are custom-made, allegedly to “balance” women’s personal hormone profiles. After measuring hormone levels through saliva and/or blood tests, a bioidentical formulation is created to allegedly address each woman’s needs based on her personal specifications.

However, information from saliva tests is considered unreliable, since a woman’s salivary hormone levels can vary throughout the day (AACE 2007; Endocrine Society 2006; FDA 2008a). Plus, it is unclear how saliva tests could accurately reflect the overall hormonal status in the body. “Some hormones, like cortisol, are accurately reflected in saliva,” says Liu. “But levels of testosterone, progesterone and estrogen do not closely correlate with either blood serum or saliva levels.”

That means that trying to determine optimum hormone levels may be a near-impossible feat. First, every woman has different levels. Also, according to Liu, “a menopausal woman not only lacks the same ratios of hormones as she did when she was premenopausal, [but] there isn’t any way to predict what her former status was, nor what the mix should be.” While the idea of customization sounds good on paper, its practicality is doubtful. “That’s why traditional HRT is not prescribed according to hormone levels, but according to symptoms,” says Liu.

Despite the negative findings of the 2002 WHI study, conventional hormone therapies are still considered effective and safe when prescribed properly. The medical recommendation is to take the lowest dose possible to help symptoms for the shortest time period needed (FDA 2008b). “The idea that bioidenticals are more personalized—and therefore more effective—is more of a marketing concept than a reality,” says Liu.

Are Bioidenticals Safer Than HRT?

Advocates say yes. But medical experts from the FDA and ACOG point out that these claims are not evidence based, and research needs to be conducted, not only to prove the purported benefits and to quantify the risks of bioidenticals, but also to compare both types of therapy.

One safety concern is that bioidenticals may not always contain reliable doses of the hormones, because—as “compounded” products—they are not bound by strict FDA regulations for manufacturing. In fact, a 2001 analysis by the FDA of 29 bioidentical products found that 34% failed one or more quality tests, and 90% of those that failed demonstrated a lower-than-expected potency (ACOG 2005). In other words, the products contained less of the active hormone than expected and advertised.

Another area of concern with bioidenticals is the form of estrogen often used: estriol. The FDA has not approved estriol for any purpose. Bioidentical advocates argue that estriol is approved and highly prescribed in Europe and other countries (Marks 2004; Holtorf 2009). However, the product approval standards of European drug agencies are more liberal than those of the FDA. Presently, only certain pharmacies have FDA permission to compound drugs that include estriol (Kuehn 2008). Bioidentical advocates have petitioned to reverse the FDA restrictions—a move that is currently being considered by Congress.

The Bottom Line on Bioidenticals

“I’m not against [bioidenticals] and have patients who have used them,” says Liu. “It’s just the philosophy behind them that is unsound, [and] the lack of evidence. I don’t think they are unsafe—or any more dangerous than traditionally prescribed hormones. But it is a mistake to assume that [bioidenticals] are safer when there is no evidence to show this.”

While the jury is still out on bioidenticals, fitness professionals should continue to encourage their clients to discuss any type of hormone therapy with their own healthcare providers. n

Despite the negative findings of the 2002 WHI study, conventional hormone therapies are still considered effective and safe when prescribed properly. The medical recommendation is to take the lowest dose possible to help symptoms for the shortest time period needed.


American Association of Clinical Endocriniologists (AACE). 2007. Reproductive medicine committee position statement on bioidentical hormones, July 15, 2007.; retrieved Jan. 22, 2010.

American College of Obstetricians and Gynecologists (ACOG). Committee on Gynecologic Practice. 2005. Committee opinion: Compounded bioidentical hormones. Obstretrics & Gynecology, 106 (5), 1139–40.

Boothby, L.A., & Doering, P.L. 2008. Bioidentical hormone therapy: A panacea that lacks supportive evidence. Current Opinion in Obstetrics and Gynecology, 20, 400–407.

Cirigliano, M. 2007. Bioidentical hormone therapy: A review of the evidence. Journal of Women’s Health, 16 (5), 600–31.

Endocrine Society. 2006. Position statement on bioidentical hormones. Available at


_10_25_06_w_Header.pdf; retrieved Jan. 22, 2010.

Holtorf, K. 2009. The bioidentical hormone debate: Are bioidentical hormones (estradiol, estriol, and progesterone) safer or more efficacious than commonly used synthetic versions in hormone replacement therapy? Postgraduate Medicine, 121 (1), 1–13.

Kuehn, B.M. 2008. FDA warns claims for pharmacy-made “bio-identical” hormones are misleading. Journal of the American Medical Association, 299 (5), 512.

Marks, M. 2004. Letters to the Editor. Menopause, 11 (6), 641–43.

U.S. Food and Drug Administration (FDA). 2008a. Bio-identicals: Sorting myths from facts.

consumer/updates/bioidenticals040808.html; retrieved Jan. 22, 2010.

U.S. FDA. 2008b. News Releases: FDA Takes Action Against Compounded Menopause Hormone Therapy Drugs.; retrieved Jan. 22, 2010.

Women’s Health Initiative (WHI). 2002. Risks and benefits of estrogen plus progestin in healthy postmenopausal women principal results from the Women’s Health Initiative randomized controlled trial. Journal of the American Medical Association, 288, 321–33.

IDEA Fitness Journal, Volume 7, Issue 5

© 2010 by IDEA Health & Fitness Inc. All rights reserved. Reproduction without permission is strictly prohibited.

About the Author

Martica Heaner, MA, PhD

Martica Heaner, MA, PhD IDEA Author/Presenter

Martica Heaner, PhD, MA, MEd, has a weekly column on and is the author of several books. She has a doctorate in behavioral nutrition and physical activity and holds two master’s d...


  • Log In to Comment
  • Raymond Kitchens

    Agree with the reveiwer above. Stick to what you know, and if you aren't a prescribing provider, defer to them for advisement. The statement "They (natural) are derived from plant sources, whereas synthetic hormones come from animal sources" IS WRONG. Synthetic is made in the lab AND does not occur in the human body.
    Commented Mar 27, 2013
  • Andre Baker

    The truth is there are several "FDA approved" bio-identical hormones that are commercially manufactured. They have passed clinical trials... estradiol patches and other trans-dermal forms (Vivelle Dot, Evamist), Prometrium for progesterone and testosterone in transdermal (Androgel) and injectable forms. Thyroid (Synthroid) is, "bio-identical" and has been used for years.. and Humalin (an insulin....) all are hormones and affect the complex metabolic system....Are bio-identical/bio-similars safer than those that have had a molicule changed so the body doesnt know exactly what to do with them? Would you rather replace what is missing with the same structured molecule or one that is almost like the one your body isn't makeing any more? With any medical therapy there is a chance for unwanted side effects or adverse reactions. Unless you happen to be a prescribing medical professional it is best to refrain from discussing topics outside your scope of practice and refer patients on for their medical needs.
    Commented Feb 01, 2011
  • Lisa Roper

    You don't mention getting a baseline hormone test to prepare for the onset of perimenopause, which causes the most discomfort due to fluctuations. It's ESTRADIOL, not ESTRIOL that is found in most HRT. Point out to your readers the 3 estrogens and the one most used: ESTRADIOL. Bio HRT can give women many choices for their individual needs - QUALITY OF LIFE is one of them, and we need the right to choose.
    Commented May 14, 2010

Trending Articles

How to Teach HIIT to Everyone

High-intensity interval training has been riding a wave of popularity, and it seems everyone wants to give it a try. However, intense interval training is nothing new. Group fitness instructors have b...

Mindful Walking

Walking can be more than just moving physically from one location to another. It can be a metaphor for your larger life journey. Things you&...

Smooth Move: Creative Additions to Consider for Smoothies

When looking for a quick breakfast or post-workout nourishment, almost nothing beats a smoothie. Whirl in the right ingredients and the blen...

Nuts and Peanuts Reduce Cardiovascular Risk and Prolong Lifespan

While there have been numerous studies in recent years touting the health benefits of nuts and peanuts, new research published online March ...

20 IDEA World-Renowned Presenters Share Advice on Success and Happiness

We asked some of this year’s most influential and motivating IDEA World Fitness Convention™ presenters to share the single piece of advice they would give another fitness/health pro to hel...

Cut Risk of Alzheimer’s with MIND Diet

Conservative adherence to a new diet, appropriately known by the acronym MIND, could significantly lower a person’s risk of developing Alzheimer’s disease, according to a paper published o...

Yes, You CAN Develop Better Eating Habits

Analogous to laying out your exercise gear so it’s the first visual reminder you have of your commitment to exercise each day, imagine...

7 Ways to Help a Client Boost Adherence

Once a client has decided to make nutritional changes to support weight loss, you can play a key role in developing an action plan that is m...

The Reason Your Clients Don't Achieve Their Goals

Lots of people hire personal trainers or join group fitness classes hoping to lose weight. Yet many fail to meet their goals. New research suggests that “progress bias”—overestimatin...

Recipe for Health: Picadillo-Stuffed Peppers

If you don’t believe that authentic Mexican cookery is “whole” and healthy, you need to take a deep dive into Mexico: The Cookbook (Phaidon 2014), the first truly comprehensive bible...

Show More