Dr. Mary Claire Haver

You've talked about it on the show before.

It has over 50 different estrogens in it.

It's actually proprietary.

When I looked into the history of this, I actually gave a talk a few years ago on it.

I was like, no one knows what's in this.

You know, it's like random estrillin and things I can't pronounce.

But as I said, you have an estrogen receptor where there's actually two, an alpha and a beta.

There's two other minor ones, right?

So it doesn't matter what the estrogen is as long as it targets that receptor.

So conjugated equine estrogen targets the receptor, and it's actually a little bit stronger at the receptor.

And that's why we use it at a little bit of a lower dose, but it is more potent than natural estradiol.

Okay.

So bi-est is kind of short for bi-estrogen.

And what it is, is it is a combination of estradiol and estriol.

So estriol is another form of estrogen that is bioidentical.

It is oftentimes touted as, quote, safer in certain ways.

But again, the way to think about this is there is an estrogen receptor.

And so there are estrogen receptors all over the body.

estriol is going to work only on that receptor.

And the only difference is what is its affinity.