One of my favorite journal articles of all time is titled “In Defense of Progesterone: A Review of the Literature” by Allan Lieberman, MD, and Luke Curtis, MD.
These two physicians wrote one of the most comprehensive and evidence-based defenses of progesterone I have ever seen.
A few months ago, I was asked on a podcast what my favorite hormone is. My answer was simple: progesterone.
I love it because it is one of the most misunderstood hormones in all of medicine.
And a big part of that misunderstanding comes from how the term “progesterone” is used incorrectly in research and clinical discussions.
The Great Confusion: Progesterone vs. Progestins
There was a study published solely to address this issue. The authors found that the word “progesterone” is often used to describe both natural progesterone and synthetic progestins.
That is a serious problem.
Progesterone (P4) is the natural, bioidentical hormone produced by the human body.
Progestins (also called progestogens), such as medroxyprogesterone acetate (MPA), are synthetic, non-bioidentical compounds that have been shown to increase the risk of cancer, blood clots, strokes, and dementia.
Despite this, medical literature frequently uses the two terms interchangeably, creating decades of confusion and misinformation.
Just look at this quote from Lieberman and Curtis:
“Although that type of error is rampant in the medical literature, one illustrative example can be found in an article by Andrea Eisen, which refers to the Women’s Health Initiative Study (WHI) as using estrogen and progesterone.
That statement is incorrect, because the WHI used a combination of equine estrogen and medroxyprogesterone acetate (MPA), which is a progestin.”
Lieberman & Curtis, 2017
This kind of error has caused enormous harm.
What the Research Actually Shows About Progesterone
When we separate bioidentical progesterone from synthetic progestins, the evidence paints a completely different picture.
Progesterone has been shown to:
- Lower rates of uterine and colon cancers
- Support recovery in cancers such as ovarian, melanoma, mesothelioma, and prostate
- Prevent cardiovascular disease, stroke, and dementia
- Improve outcomes in traumatic brain injury (TBI)
- And importantly, not increase breast cancer risk
In primate studies, progesterone and estradiol together reduced breast cancer cell proliferation.
The placebo and synthetic hormone groups showed the opposite effect, with an increase in breast cancer cell proliferation.
That finding is profound. It suggests that bioidentical progesterone may one day even be used as a pre-surgical therapy to reduce breast cancer cell activity.
What the Authors Concluded
Lieberman and Curtis wrote:
“The authors wish to emphasize that natural progesterone is preventive of breast and endometrial cancer, and physicians should have no hesitation prescribing it.”
Lieberman & Curtis, 2017
Amen to that.
And let’s update the language a bit: providers should have no hesitation prescribing it.
Because the call here is clear and powerful.
The Call to Action for Providers
Our communities need us to step up.
We hold the power to reduce cancer risk, prevent dementia, improve cardiovascular health, and help women live lives full of meaning and vitality.
And we can do that through one of the safest, most effective, and best-studied interventions available: HRT.
The longer we wait to act, the more unnecessary suffering continues among our patients and loved ones.
If you are ready to truly master this field, start with the HRTU Master Course. It will give you the foundation you need to understand hormone therapy at a deep physiological level.
Because when the Advanced Female HRT Course launches later this year, you will want this foundation locked in.
It all starts with becoming an expert in the fundamentals, and that begins inside the HRTU Master Course.
Conclusion: Progesterone Deserves a Defense
Progesterone is not just a reproductive hormone. It is protective, restorative, and foundational to women’s health.
When prescribed appropriately, it improves quality of life and lowers disease risk across multiple systems.
It is time for more providers to understand what progesterone truly does and to feel confident prescribing it.
If you want to lead this change, HRT University is where you begin.
For a complete overview of hormone replacement and bioidentical hormone therapy, see BHRT vs HRT: A Clinical Guide for Prescribing Clinicians.
