Episode Details

What if the estrogen missing from your hormone therapy wasn't left out because it failed, but because no one could build a profitable drug around it?

Your body naturally produces three estrogens: estrone, estradiol, and estriol. Yet most hormone therapy replaces only estradiol. It is easy to assume that estriol was studied, found ineffective, and discarded. But that is not what happened. It didn't necessarily lose a scientific argument; it lost a business one, and over time, we mistook that silence for proof.

That missing conversation matters because estrogen does not produce the same effect everywhere in the body. And this could help explain why some women see their hot flashes disappear on estradiol while continuing to struggle with mood changes, disrupted sleep, brain fog, gut problems, recurrent UTIs, or unexplained inflammation. Their treatment may not be failing; it may simply be addressing only part of the hormonal picture.

In this episode, I talk about why you never hear about estriol, why it's not about effectiveness, and when to consider asking your doctor about it.

What You'll Discover in This Episode

• Why your body produces three estrogens, while most hormone therapy replaces only one

• How estriol may have lost a business argument, not a scientific one

• Why the absence of an FDA-approved estriol product does not automatically prove that estriol is ineffective

• The crucial difference between a hormone binding to a receptor and fully activating it

• How estrogen receptor alpha and estrogen receptor beta can produce very different effects throughout the body

• Why estradiol can successfully relieve hot flashes while mood, sleep, memory, gut, or inflammatory symptoms remain

• What research involving the brain, gut, immune system, and urogenital tissue suggests about receptor beta

• What human multiple sclerosis trials may reveal about estriol's potential immune effects, and what those studies cannot yet prove

• Why elevated cholesterol and metabolic health may further complicate estrogen receptor signaling

• The strongest scientific objections to combination hormone therapy—and why they deserve serious answers

• Why estriol being a "weaker" estrogen may be a feature in some formulations, not necessarily a flaw

• How poorly timed blood tests can make a compounded hormone cream appear ineffective

• What to ask your provider if your current estrogen therapy is helping, but you still do not feel like yourself

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Research Referenced in This Episode

Every study below includes a PubMed ID (PMID), which you can use to find the original paper at PubMed.

This episode discusses hormone therapy for educational pu