The current understanding about the impact of estrogen on heart health in midlife women is complicated. Too often, individual facts are cherry-picked from studies and shared on social media, and they don’t give the whole picture. To better understand this topic and try to convey the whole picture, we reached out to Dr. Nanette Santoro.
Dr. Santoro helped clarify what is known and still not known from research findings, so you have accurate information on which to base your health decisions. We are grateful for how generous she was with her time as this isn’t an easy topic to explain!
Estrogen and Heart Health in Midlife Women: 2 Things that are reasonably clear
1: Estrogen therapy in young women (under 45) who lose ovarian function, either due to the surgical removal of their ovaries or because their ovaries stop functioning, is likely to be beneficial.
Why do we use the word “likely”?
- We use the word “likely” here because there are no randomized trial data or strong observational data that show that giving estrogen to these women under 45 reduces heart attacks or heart disease.
- What we know comes from studies that show a positive effect of estrogen on endothelial function. Endothelial function is an “intermediate marker” of heart health. Good endothelial function is linked to healthy blood pressure and future heart health.
- Because attempting to gather data from randomized control trials could put the women in the placebo (no treatment) group at risk, there is a consensus that we do not wait for these data and therefore treat women under 45 women who lose ovarian function based on the impact of estrogen on endothelial function in women of this age.
2: Estrogen is not good for heart health in all cases and is not beneficial in women with existing disease.
- Giving estrogen to women with existing heart disease does not slow the progression of heart disease, nor does it prevent additional heart attacks.
- In fact, in a study that tested estrogen therapy in women with heart disease, women had more negative heart events (e.g., heart attacks, bypass surgery, the need for stents) in the initial years of taking estrogen. After an initial phase, the risk for negative heart events went back to normal for this group of people, but didn’t improve.
What is still unclear about Estrogen and Heart Health in Midlife Women
In women after menopause without heart disease in the expected age range of 45-55, the findings are mixed.
Two similar (but not exactly the same) clinical trials in healthy women after their final period investigated the rate of accumulation of plaque in neck arteries and calcium in heart arteries in those given hormones and those who were given inactive treatment (placebo).
These studies did not find the same results.
Study 1 investigates whether the timing of treatment from menopause of 1 product combination affects markers of heart disease (accumulation of plaque in neck arteries and calcium in heart arteries)
- 1 product combination was tested (oral estradiol + vaginal progesterone) against placebo
- 2 groups of women
- those less than 6 years from their final period
- another 10 + years from their final period
- Findings
- Oral estradiol + vaginal progesterone slowed the rate of plaque accumulation in neck arteries in women who were within 6 years of their final menstrual period more than placebo (a positive finding)
- Oral estradiol + vaginal progesterone did not slow the rate of plaque accumulation in neck arteries in women who were 10+ years after their final period more than placebo. (no effect finding)
- There was no difference in effect on the calcium in heart arteries in women who were within 6 years of their final menstrual period and using oral estradiol + vaginal progesterone as compared to placebo. (no effect finding)*
- In this same trial, there was no effect on the calcium in heart arteries in women who were 10+ years after their final period and using oral estradiol + vaginal progesterone as compared to placebo. (no effect finding)*
Study 2 investigates 2 product combinations on markers of heart disease (accumulation of plaque in neck arteries and heart arteries)
- 2 hormone product combinations (treatments) were tested
- oral conjugated equine estrogen (a different oral estrogen product) + oral progesterone
- an estradiol patch + oral progesterone (***the most commonly prescribed products today)
- Findings
- There was no difference in the rate of plaque accumulation in neck arteries with oral conjugated equine estrogen + oral progesterone as compared to placebo. The finding from study 1 was not replicated.
- There was no difference in the rate of accumulation of plaque in neck arteries with an estradiol patch + oral progesterone as compared to placebo (no effect finding)
- There was no difference in the effect on the rate of calcium accumulation in heart arteries with oral conjugated equine estrogen + oral progesterone as compared to placebo (no effect finding)*
- There was no difference in the effect on the rate of calcium accumulation in heart arteries with an estradiol patch + oral progesterone as compared to placebo (no effect finding)*
* The power of both studies to detect differences in the rate of calcium accumulation in heart arteries was quite low, so these null findings were not a surprise. Most women in their 50s have low rates of calcium accumulation in heart arteries.
The problem with what is shared on social media about Estrogen and Heart Health in Midlife Women
Often, it is the one positive finding that gets shared on social media, which leads quick scrollers to conclude that estrogen is clearly beneficial for heart health. Understanding more about the research itself reveals that this doesn’t convey the whole picture.
In addition, the positive finding was in women who took an oral estrogen product and a vaginal progesterone product. Most women today use an estradiol patch and oral progesterone. Other research suggests that the way you take hormones (oral, vaginal or transdermal meaning through your skin via a patch) has an effect on how they work in your body. More research is needed here.
More of what we still don’t know about Estrogen and Heart Health in Midlife Women
- Why the slowing accumulation of plaque in the neck artery from study #1 wasn’t replicated in study #2.
- How important is the time from menopause in relation to when hormones are started? In study 1, participants were less than 6 or more than 10 years from their final menstrual period. In study 2, the participants were 6 to 36 months from their final menstrual period.
- Whether certain genetic factors related to how a person’s body uses estrogen may make it good for some people’s hearts but not others.
- Whether our bodies need estrogen up until some age but then no longer need estrogen at which point adding it back is no longer beneficial.
This post is not to scare people away from using estrogen. Dr. Santoro is clear that for most women who are experiencing hot flashes and night sweats (and often the sleep and mood symptoms they can lead to), estrogen and progesterone, for those with a uterus, should be used to relieve symptoms. Watch our video discussion on this topic here. However, she is also clear that the claims that estrogen should be taken in the absence of hot flashes and night sweats for future heart health are not substantiated by research at this point in time.
