If you’re considering hormone therapy for your menopause symptoms, you may have some questions about heart health. The science around this subject is complex, but recent research has pointed to two important findings: First, estrogen does protect heart health under certain conditions. And second, the cardiovascular impact of hormone therapy depends largely on timing. Let’s explore the connection between estrogen and heart health.
As far back as the 1970s, researchers suspected that estrogen offered protection against cardiovascular disease. This was based on the simple observation that women (whose estrogen levels are higher) tend to develop heart disease about ten years later than men. This timing coincides with the menopausal transition, which causes estrogen levels to fall. Certain risk factors for heart disease (such as high blood pressure) also increase around the time of menopause.
Today, it’s widely accepted that estrogen offers cardiovascular benefits and that menopause can influence your heart health profile in complex ways. Here are some areas where we see this impact:
Blood vessels naturally constrict and dilate in the course of your daily life. When they’re constricted, your blood pressure rises. This is useful in certain situations (e.g. when it’s cold and you’re preserving vital heat), but it can be damaging to your heart and blood vessels if pressure remains high for an extended time.
Estrogen is a powerful vasodilator: It allows your blood vessels to relax, easing the burden on your circulatory system. This explains why women tend to have lower blood pressure than men before menopause, but experience a significant blood pressure increase during the menopause transition.
When a person experiences stroke or heart attack, the underlying cause is often atherosclerosis: a narrowing and hardening of the blood vessels. Atherosclerosis happens when cholesterol—a type of fatty substance that circulates in your bloodstream—begins building up along the inner walls of your blood vessels. It gathers into hard plaques that prevent your blood vessels from flexing normally. Ultimately, a blood vessel can become completely obstructed or burst, causing catastrophic damage to the heart or brain.
Estrogen seems to reduce atherosclerosis by helping the body remove inflamed cells (a process called autophagy) which could otherwise grow into plaques. A wealth of scientific evidence shows that low levels of estrogen causes increased atherosclerosis.
Fibrosis is a biological process that can happen almost anywhere in the body. It refers to the formation of undesirable new tissue that can obstruct the normal functions of your organs. When fibrosis occurs in your heart, there is a buildup of proteins between the cardiac tissues that can contribute to many different forms of heart disease.
While research in this area is ongoing, estrogen seems to protect against fibrosis by preventing the formation of fibroblasts—cells that create the harmful proteins seen in fibrosis. Estrogen also seems to activate certain helpful genes in your heart tissues which ultimately prevent the fibrosis process from taking hold.
The basic chemistry of living bodies requires a type of particle called reactive oxygen species (ROS). These are powerful, highly reactive molecules that play a critical role in normal metabolism, including in your heart and blood vessels. But ROS are a double-edged sword. When too many of them accumulate in your tissues, they can cause damage on the cellular level. This is called oxidative stress. In your cardiovascular system, it’s been linked to ischemia, hypertension, and heart failure.
Estrogen can help protect against oxidative stress. This action is twofold: First, it helps prevent the formation of ROS, nipping oxidative stress in the bud. And second, it acts as an ROS “scavenger,” sweeping up excess ROS molecules in the heart and blood vessels.
As we discussed above, the cardioprotective benefits of estrogen have been observed since the 1970s. For this reason, most researchers expected menopausal hormone therapy (which uses synthetic estrogen to supplement your falling natural hormone levels) to prevent heart disease in women. It therefore came as a major surprise when, in the early 2000s, the Women’s Health Initiative (WHI) reached a different conclusion: hormone therapy seemed to increase the risk of certain types of heart disease.
In the two decades since those results were published, the study of hormone therapy and women’s heart health has greatly evolved. Today, according to the North American Menopause Society (NAMS), the benefits of hormone therapy outweigh its risks for healthy women who are within 10 years of the menopause transition. This conclusion is based on both newly published studies and older science (such as the WHI) that researchers have revisited.
Increasingly, research has found that timing is important—i.e. that hormone therapy provides heart health benefits as long as it’s taken at the right time. A 2020 scientific statement from the American Heart Association endorses this idea: After reviewing extensive data on the subject, the group concluded that hormone therapy offers significant heart health benefits in women who are under 60 years of age, or who have reached menopause within the last decade. After this point, they write, hormone therapy may begin to have negative effects on heart health.
Similarly, a systematic review from 2020 found that the cardiovascular impact of hormone therapy depends on the characteristics of the people being treated—including the timing of their menopause transition. The authors argued that hormone therapy can thus deliver significant heart health benefits as long as the patient’s unique risks and goals are considered appropriately.
Estrogen is an incredibly important hormone that plays a role in virtually every organ and tissue in your body. It is now well-established that it offers important cardioprotective benefits, which is why heart disease risk factors increase during and after menopause. For people who are under a certain age or have recently experienced menopause, it may be possible to reap these benefits using menopausal hormone therapy. If you’re interested, talk with a doctor about your holistic health situation and consider the possible costs and benefits.
Reviewed by Leah Millheiser, MD, Evernow Chief Medical Officer, September 2022