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Why It’s Vital to Understand the Hormones Used In HRT

Unraveling the Differences Between Natural, Bioidentical, and Non-Bioidentical Hormones.

Mia West
November 22, 2023
Medically-reviewed and fact checked by Ryan Lester, PA-C

Consider this: if there was a pop quiz testing your grasp of the differences between natural, bioidentical and non-bioidentical hormones, could you confidently answer? Before researching this article, even with experience on two different hormone replacement therapy programs (“natural” and bioidentical), I’d likely have failed. During my stint on a “natural” program, my lack of knowledge had me thinking my plant-based treatment was the healthiest, most effective choice. Turns out I was wrong.

Being well-informed about these distinctions is crucial. The terms are frequently misused by misinformed health and wellness influencers and the media. Healthcare practitioners, lacking hormone education (which is the vast majority), also contribute to the confusion and are known for using them incorrectly. Moreover, the descriptors themselves might be misleading, contrary to what one might perceive them to be. 

Given that this involves your body, having insightful knowledge is indispensable, so we tapped Wellcore’s resident hormone expert Ryan Lester, PA-C to provide some clarity and fact-check our research. Lester is a Physician Assistant who specializes in personalized preventative medicine and is certified in Bioidentical Hormone Replacement Therapy at the esteemed Worldlink Medical.

Bioidentical Hormones

According to a Mayo Clinic Proceedings report, the term bioidentical hormone does not have a standardized definition and thus often confuses patients and practitioners. Bioidentical hormones share an identical molecular structure with the hormones naturally produced by the human body. Being the closest to what our bodies actually create, bioidentical is oftentimes referred to as natural, adding to the confusion. They’re typically synthesized in a laboratory, which allows for precise control over dosage and consistency. Commonly prescribed bioidentical hormones include estradiol, progesterone, and testosterone.

Natural Hormones

The word natural in the English Oxford Dictionary means “existing in or derived from nature; not made or caused by humankind.” When it comes to hormones, the natural ones are usually extracted from animals. Although some can be safe and effective, others like Premarin can be highly problematic. Premarin, or conjugated equine estrogen, was once the best-selling drug in the country for treating hot flashes and other menopausal symptoms. Its origin? It is derived from pregnant horse urine. It has been found to have less than 5% estradiol (the most active and effective form of estrogen for treating menopausal symptoms) and up to 10 or more different forms of non-human estrogen. Studies demonstrate that it can cause serious side effects and even increase one’s risk of a heart attack and/or stroke. 

Is it derived from nature? Sure is. Is it the safest and most effective option for menopausal women? Not even close. The takeaway; natural doesn’t always mean better.

Non-Bioidentical Hormones 

Non-bioidentical hormones, often referred to inaccurately as synthetic hormones, are also synthesized in a lab. They’re chemical composition is similar but not identical to the hormones produced by the human body. A type of non-bioidentical progestin called Provera or medroxyprogesterone acetate was introduced for medical use in the U.S. in 1959 and until the results of the Women’s Health Initiative (WHI) study in the early 2000’s, was one of the most commonly prescribed hormones for menopause. In some women, it is still used today as an oral contraceptive and to treat conditions such as abnormal uterine bleeding. The results of the WHI demonstrated that Provera, when used with Premarin, increases the risk of coronary heart disease, breast cancer, stroke, and blood clots in menopausal women.

The Complication: Synthetic

Synthetic hormones are defined as a substance that is made by chemical synthesis. This means a bioidentical hormone is technically synthetic; however, it is still identical to the hormone produced by the human body which is most important. The most common bioidentical hormones used today are estradiol, progesterone, and testosterone.  A majority of high quality studies in the last 50 years have repeatedly demonstrated that bioidentical hormones are the safest and most effective way to relieve symptoms and reduce the risk of the most common chronic diseases - heart attacks, strokes, dementia, and cancer.  


In the realm of hormone replacement therapies, the choices between natural, bioidentical, and non-bioidentical hormones are complex and multifaceted. If you’re a Wellcore patient, don’t forget you have access to a clinical care team of hormone specialists who can answer your questions. For ongoing education and support, consider joining the Wellcore Women Facebook Community which was created to empower women in making informed decisions about their hormonal health. At the end of the day, patients should consult with knowledgeable healthcare professionals to determine the most suitable option based on their individual health needs and considerations.


Join millions of men and women who are improving their health by ordering the Wellcore At-Home Assessment Kit today.

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About the Author

Mia West

A former journalist, Mia brings a high energy approach to communications rooted in insights, culture and brand DNA. She is driven by helping brands crystalize their story and foster meaningful, emotional connections with audiences. Over the years she has collaborated with prominent brands such as Petco, Keurig Dr Pepper, Jaguar Land Rover, Revlon, and Procter & Gamble Beauty, as well as many others in the retail, health & wellness, beauty, lifestyle, and sustainability realms. A California native, she lives in San Diego with her family at the beach.

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