How Safe and Effective Are Bioidentical Hormone Therapies?

August 31, 2017

by Tara Haelle

The popularity of bioidenticals has surged over the past decade, particularly among women with safety concerns about hormone therapy (HT) during and after menopause. Yet many women may not realize how little research exists on these products’ safety, effectiveness, purity, strength, or quality.

Bioidenticals are hormones derived from plants and/or synthetically produced or altered to have a similar chemical structure as hormones produced by the body. They may also contain FDA-approved hormone products. Bioidenticals can be ordered online or compounded at pharmacies using a healthcare provider’s instructions, but the FDA does not regulate most of these products because they’re considered supplements. The agency leaves regulation of compounded formulations with FDA-approved products to the states. Little to no regulation controls bioidenticals’ production and distribution.

Women typically choose to use bioidenticals to manage the menopause symptoms that HT treats. Menopause causes women’s bodies to make less estradiol, the estrogen responsible for maintaining bone mass and vaginal tissue. Lower estradiol levels increase risks of osteoporosis and bone fractures and often lead to vaginal atrophy. HT therefore involves taking estradiol to replace what women’s bodies aren’t making. Women who still have a uterus also take progesterone to reduce the risk of endometrial cancer. (Estradiol by itself can cause abnormal cell growth in women without hysterectomies.)

However, the large Women’s Health Study raised concerns about HT. The study investigated HT’s safety and effectiveness but was cut short because it became quickly apparent that HT increased risks of heart disease and breast cancer, though the study also found HT reduced risks of colorectal cancer, bone fracture, and osteoporosis. The consensus of healthcare professionals is that women should individually assess HT’s risks and benefits for their particular situation with their doctor.

Many women concerned about HT risks have opted for bioidenticals, which include forms of estradiol, estrone, and estriol estrogens plus progesterone optimized (“micronized”) for better absorption. Past surveys found one of the biggest reasons women choose bioidenticals is their belief that the products are natural or made “without chemicals.” Unfortunately, though, that’s not the case. Even plant-derived bioidenticals are usually altered in the laboratory to make them similar to human hormones, and all of them are made up of chemicals.

The term “bioidentical” is a marketing term rather than a scientific one, explains the American College of Obstetricians and Gynecologists (ACOG). The hormone therapy products approved by the FDA come from both plant and animal sources and are equally “natural” as bioidentical products. The biggest difference between FDA-approved hormone therapy products and bioidenticals is that bioidenticals are unlicensed and not tested for safety or effectiveness. Unlike FDA products, bioidenticals also aren’t tested for purity and consistent potency.

Women may also choose bioidenticals for their individualization. For example, a doctor may prescribe a compounded formulation instead of an FDA-approved product containing peanut oil if the woman has an allergy. Beyond these cases, however, “hormone customization is very difficult to achieve because blood hormone levels are difficult to measure and regulate accurately due to normal physiologic variations,” the Endocrine Society wrote in their statement on bioidenticals.

Some providers use saliva or blood tests to assess hormone levels, but research has shown these tests are unreliable and cannot accurately measure levels. Further, the body cannot tell the difference between bioidentical hormones and ones made by the body, so tests cannot tell how much bioidenticals are absorbed. Some bioidenticals even use plant sources, such as Mexican wild yam, that produce estrogen the human body isn’t capable of using. Because these levels cannot be tested and the products aren’t tested, women can also receive underdosage or overdosage. Overdosage can increase the risk of abnormal endometrial cell growth, endometrial cancer, and blood clots.

In fact, the biggest concern with bioidenticals is safety. One survey found 71% of women believe “natural hormones” have fewer or no risks and 69% thought they had fewer or no side effects. Yet bioidenticals haven’t been studied enough to show safety. Chemically, they would be expected to have the same risks as FDA-approved hormone therapies — but they aren’t required to carry the same black-box warnings as FDA products, even if the risks are the same.

Neither ACOG nor the Endocrine Society say women shouldn’t take bioidenticals. Both organizations emphasize the importance of informing women of the risks and lack of scientific evidence for bioidenticals’ safety and effectiveness, and both call for greater regulation of these substances, especially given their continued popularity and similar risks to hormone therapy.

An earlier version of this article was published in the spring 2017 DES Action USA newsletter.

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