The Truth About Estrogen: A Masterclass on Hormones and Health

Estrogen influences far more than hot flashes. From mood, memory, and sleep to skin, sex, and long-term health, its impact runs deep. When estrogen levels fluctuate and eventually decline, it changes everything.

In a recent webinar, our Community Manager, Rachel Hughes, sat down with Dr. Amy Killen, a physician specializing in hormones, regenerative medicine, and longevity, for an honest and empowering conversation about what estrogen does, why it matters, and how to navigate the shifting hormonal landscape of midlife and beyond.

Together, they unpacked symptoms, debunked myths, and shared actionable insights for feeling your best during your “Queen Phase™.”

This transcript has been edited for clarity and brevity. As always, the content is for educational purposes only and is not intended as personal medical advice.

We highly recommend watching the full webinar on our YouTube channel. It includes additional context, Q&A, and insights you won’t want to miss.

Rachel Hughes: Thank you for being here. There are still a lot of big misunderstandings about estrogen. If you had a megaphone and could shout one message to women about estrogen, what would it be? 

Dr. Amy Killen: Estrogen is about more than reproduction. It supports every major organ system in our bodies, not just fertility. And it’s important throughout our lives, not just during the reproductive years.

Rachel Hughes: And what are we still fundamentally getting wrong about estrogen therapy?

Dr. Amy Killen: The biggest lingering misconception from the Women’s Health Initiative is that estrogen therapy causes breast cancer. It’s a nuanced topic, but randomized trials show it doesn’t increase the risk. Still, that fear holds many women back.

Rachel Hughes: It does. And when you speak with women and interact on platforms like this, or out in the world, what do you want women to understand are the hidden costs of that misunderstanding? Dr. Amy Killen: When estrogen drops sharply at perimenopause, it doesn’t hit zero, but it gets close. That loss is linked to many chronic conditions we might prevent or reduce with estrogen therapy. These include cardiovascular disease—the leading cause of death in women—osteoporosis, muscle loss, and even dementia. Starting estrogen early and appropriately could make a big difference.

Rachel Hughes: So appreciated. Thank you. I follow you and I listen to you, and I feel like there’s the science you offer, and then there’s the wellness world. And they’re not always in opposition, but things can get murky. Where does estrogen fit into the landscape?

Dr. Amy Killen: I’m a traditionally trained doctor, but I’ve worked in integrative and functional medicine for over a decade, so I often feel like I’m standing between two worlds, trying to take the best from each. Estrogen still sits firmly in the conventional medicine space. It’s a prescription medication. But interestingly, those of us in integrative medicine have been using bioidentical hormones like estradiol and progesterone for the past 20 years. Many in that space never stopped after the Women’s Health Initiative, while conventional doctors pulled back. In some ways, integrative practitioners have been ahead, especially in how they’ve continued to use and trust these hormones.

Rachel Hughes: You talked earlier about how estrogen affects different systems in the body. Can you walk us through your top three or however many come to mind? Dr. Amy Killen: Sure! My top five are blood vessels, brain, bones, muscles, and the pelvic floor. So, three B’s: blood vessels, brain, and bones, plus muscles and pelvic floor. We probably have the most data and agreement around estrogen’s benefits for bones. Even people hesitant about estrogen therapy usually agree it reduces osteoporosis risk by about 30 to 40 percent and fractures by about 40 percent when started early. So bone health is an area with strong consensus. There’s more disagreement about cardiovascular benefits and dementia because people often look at the data in aggregate rather than focusing on women who start estrogen at the right time. Timing and context really matter. But bones, no one argues that estrogen doesn’t help. Rachel Hughes: And can you explain what’s happening on a cellular level when estrogen declines? Dr. Amy Killen:

Absolutely. Most cells in the body, though not all, have estrogen receptors. There are different types like estrogen alpha and beta, and they respond differently depending on the tissue. Estrogen is an anabolic hormone. It builds things up, like bones, muscles, and connective tissue. That’s why it strengthens bones and helps maintain muscle mass. In tissues like the breast and uterus, it can cause growth, which is why unopposed estrogen for long periods can be problematic. I think of estrogen as a builder. She wants to grow, strengthen, and energize. But it’s important to balance estrogen with progesterone if you have a uterus, which plays a calming, regulating role. You need both: estrogen to build and progesterone to keep things in check.

Rachel Hughes: That's such a great illustration of what estrogen does and wants to be in our bodies and systems. It sounds like estrogen can be a real longevity tool. 

Dr. Amy Killen: I think that estrogen is the billion dollar longevity drug that we've been seeking for decades, but we already have it, and it costs us less than $30 a month.

Rachel Hughes: Amazing. Love that. Let’s talk more about longevity. How does estrogen complement regenerative approaches like PRP or stem cells? Dr. Amy Killen: I do a lot of regenerative medicine. I use PRP, stem cells, exosomes, and more for skin health, scalp, muscles, joints, and overall body health. But for those treatments to really work, you need a healthy system to start with. For example, if someone comes in and they’re a smoker, I won’t treat them with regenerative therapies. If you don’t have fertile soil, it doesn’t matter how many seeds you plant. Estrogen helps keep that internal environment healthy. It supports the body and creates the foundation those advanced therapies need in order to be effective. And it's not just about estrogen. It’s about combining it with all the other healthy practices that prepare your body. Then, when you do add next-level treatments like regenerative medicine or plasmapheresis, they have a much better chance of working because your foundation is strong.

Rachel Hughes: Can we pivot to estrogen and sexual wellness, midlife vitality? How does estrogen affect sexual function and desire?

Dr. Amy Killen: When I think about sexual health, I use something I call the sexual response snowman. It has a few layers. At the top is desire or libido, which is your interest in having sex. In the middle is arousal, which involves blood flow to the sexual organs. At the bottom is orgasm. Estrogen can influence all of these stages.

It helps with libido, along with testosterone. It also supports arousal because it causes blood vessels to open and increases nitric oxide. That improves blood flow to the genital area, which is important for clitoral engorgement, lubrication, and overall arousal. Estrogen also plays a role in reaching orgasm.

Systemic estrogen, like a patch or a pill, can help with libido and has benefits for the pelvic floor. Low-dose vaginal estrogen, which mostly stays in the pelvic area, is helpful. It keeps the tissues healthy, improves blood flow, supports vaginal elasticity, and helps with muscle tone. So both systemic and local estrogen can be really beneficial for sexual function.

Rachel Hughes:

Great. Let’s talk about vaginal estrogen. I am emphatic about telling women to get vaginal estrogen on their shelves, no matter what. I’d love for you to speak to why that’s important, and when you’d want someone to start using vaginal estrogen. 

Dr. Amy Killen: I mean, I think that all women over the age of 45 or 50 should at least have a discussion with their doctors about starting low-dose vaginal estrogen. And, when I say low dose, we’re talking about 0.1 milligrams per dose, which is a much lower dose than you're taking if you're taking a pill or a patch or things like that in terms of how much gets in your body. It’s very important for maintaining the health of your pelvic floor, which is not just about sexual function, although that's a big part of it. It's also about preventing urinary tract infections. It's also about preventing urinary incontinence where you have bladder leakage when you cough or sneeze and you can't get to the bathroom in time. It's about preventing yeast infections. The American Urological Association just came out with their new guidelines a couple of days ago on vaginal estrogen. They did a big study with millions of women who had a history of recurring UTIs and they found a huge–like 70 percent or more–reduction in chronic UTIs just from using low-dose vaginal estrogen. It's very, very safe and we know it's safe even in breast cancer survivors.

Rachel Hughes: Thank you. Let’s get to some audience questions: Is estrogen safe if you have migraines with aura?

Dr. Amy Killen: The short answer is yes. But it should be transdermal (patch, spray, or gel) instead of oral.

Rachel Hughes: Great. Next question: I had a hysterectomy and BSO (bilateral salpingo-oophorectomy) at age 23. I was on Premarin until I was in my late 40s, and then my doctor wouldn’t prescribe it anymore. Now I’m 68 and have osteopenia. What can estrogen do for me?

Dr. Amy Killen: Estrogen can still benefit bone health even when started later in life. Estrogen can help improve bone density even in women in their 70s. Transdermal estrogen, for example, can show results in 6 to 12 months. So yes, it could still help—just be sure to consult your doctor. Rachel Hughes: Terrific. Thank you. I love this next question about dosing. Someone asks, is it okay to take more than two milligrams of estrogen per day? This person is asking about oral estradiol specifically. Dr. Amy Killen: Great question. Unlike many doctors, I’m a fan of oral estradiol. The research on its benefits for cardiovascular disease is actually stronger than for transdermal, even though transdermal is safer for things like blood clots. So yes, it's often safe to take more than two milligrams. The pharmaceutical limit is two, but that doesn’t mean you can’t go higher.

Rachel Hughes: Thank you. Here's another question we got: If a postmenopausal woman doesn’t have any symptoms, eats healthily, strength trains, and has good bone density and a good cardiovascular profile, should she still consider hormone replacement?  

Dr. Amy Killen: I think she should still consider it. Not everyone needs it to be healthy, but hormone therapy offers many benefits. Even without symptoms, it's worth discussing those potential benefits with your doctor. Rachel Hughes: I want to dive deeper into your expertise on longevity medicine. Can you talk us through it a little bit more? What would you want the lay person to know? 

Dr. Amy Killen: To me, longevity medicine is about being proactive—looking for signs of disease years before they appear and working to prevent them. At my clinic in Texas, we run extensive blood tests and screenings that go beyond what most doctors do. For example, we do a DEXA scan on every patient. I had a 28-year-old with undiagnosed osteoporosis—she had no idea. We look for early changes, like in bone density or blood sugar, before they become a problem.

We focus on what’s optimal for aging, not just what’s considered normal for your age. That’s a big shift from traditional medicine. It’s about preventing future disease, not just treating symptoms. This is where hormone therapies like estrogen, progesterone, and testosterone come in. People may not have obvious symptoms of low hormones, or they may not recognize them, but these therapies can help prevent future health issues. Rachel Hughes: This might seem like a strange question, but there's such ease and conviction in how you share this science. I feel like if more people really listened, so much fear and anxiety around hormones would disappear. For those who say, “I don’t want to,” or “I can’t,” or are afraid, or for those pushing back on social media saying, “This isn’t right,” how do you respond to that?

Dr. Amy Killen: I want every woman to feel empowered to make her own health decisions. That might mean taking no medications, doing nothing, or going all in with treatments. It’s your choice. I’m not here to tell anyone what to do with their body; I’m here to offer education for those who want it. I share what I believe works well for many people, but I don’t think it’s the only path for everyone. Rachel Hughes: I love that. Thank you. Thank you so much for being here today, this was great. 

Dr. Amy Killen:

Thank you!

For more of their insightful conversation, watch the whole webinar on our YouTube! To learn about future events, follow us on Instagram @myalloy.