The Facts About Estrogen

Estrogen is considered a "female" hormone in the same way testosterone is considered a "male" hormone. But there's a blurring at the edges and both hormones can be found in both sexes.

Estrogen is the steroid hormone responsible for secondary female sex characteristics and reproductive systems. Secondary female sex characteristics include breasts, the menstrual cycle, less body hair, rounded hips and curves, and less ability to build muscle. Estrogen is naturally produced by the body and available synthetically for clinical purposes. It plays a pivotal role in a variety of physiological processes, particularly for women, though men do experience estrogen's effects as well.

Estrogen is important for both normal bone development (such as contributing to the closure of growth plates in puberty) and bone preservation as a person ages. The hormone also plays a role in cardiovascular health in men and women alike. Although estrogen levels fluctuate in women of reproductive age, keeping them as homeostatic as possible has myriad health benefits.

There are three primary types of naturally occurring estrogen, all produced at varying levels corresponding to life phases. The first—and most common—is estradiol, which in women is produced in the ovaries. In men, the enzyme aromatase breaks free testosterone down into estrogen. Estradiol peaks during puberty and childbearing years, and production declines with age.

Another form of estrogen is estriol, the main estrogen in pregnancy, produced largely in the placenta. It plays a role in maintaining a healthy pregnancy and fetal development as well as preparing the body for childbirth and breastfeeding.

The final type is estrone, created from adipose tissue. Estrone is the weakest type, and the sole form of estrogen made after menopause.

The majority of circulating estrogen is bound to a protein, either albumin or sex hormone-binding globulin.

Synthetic estrogens include:

• Conjugate esterified estrogen
• Estradiol valerate
• Estropipate
• Ethinyl estradiol
• Quinestrol

Synthetic estrogens modify estrogen's structure, often to help it bind better to estrogen receptors or metabolize more slowly. In effect, synthetic estrogen makes estrogen work better or last longer.

Both internal and external factors impact estrogen production. Some are nonmodifiable factors, such as genetic variations and age. Estrogen levels are directly impacted by other reproductive hormones, mainly, progesterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Age has substantial effects on estrogen, as estrogen levels naturally fluctuate depending on developmental stage.

Other impacts on estrogen production come from environmental triggers, such as lifestyle practices and mental health conditions. Managing stress, getting enough sleep, exercising regularly and eating a diet with cruciferous vegetables and other plant-derived foods can all help maintain healthy estrogen levels.

A lower-than-normal level of estrogen can impact sexual development. For instance, Turner's syndrome causes a defective or missing X chromosome that can circumvent ovarian formation, cause major delays in sexual milestones and affect fertility.

In women of reproductive age, circulating estrogen may decrease for a variety of reasons. Anorexia can cause such a hormonal change, as can breastfeeding. A lower amount of circulating estrogen in these cases can cause:

• Amenorrhea (absence of menstruation)
• Bone degeneration, such as in osteoporosis
• Decreased sex drive and self-lubrication 
• Impaired temperature regulation
• Mood changes

The term "estrogen dominance" is used to describe a type of hormonal balance that's associated with symptoms such as abnormal menstruation, increased PMS symptoms, insomnia and more. Estrogen dominance is not necessarily the result of high estrogen levels but instead describes estrogen's relationship to progesterone.

It is an unofficial medical term and a debated condition that does not have a clear definition. It's also important to note that estrogen dominance as a diagnosis is not recognized by major medical associations, including the American College of Obstetricians and Gynecologists, the American Academy of Family Physicians and the Endocrine Society.

The main symptoms attributed to estrogen dominance include:

• Anxiety and/or depression
• Bloating
• Brain fog and memory problems
• Breast tenderness
• Fatigue
• Fibroids
• Hypermenorrhea (heavy or prolonged menstrual bleeding)
• Increased PMS symptoms
• Insomnia
• Low sex drive
• Missed or irregular periods
• Weight gain

For many of these symptoms, there is not a causal relationship established between elevated estrogen in relation to progesterone and these symptoms. Biochemical estrogen dominance does not equal "estrogen dominance" as a syndrome.

An imbalance between estrogen and androgen hormones in men can lead to enlarged male breasts (also known as gynecomastia), infertility and erectile dysfunction (ED). However, this is not the same concept as estrogen dominance, as these conditions in biological males relate to estrogen and testosterone.

If a man's body produces too much estrogen or not enough testosterone, the male breast tissue may enlarge.

Estrogen homeostasis is important for many reasons and is correlated to just as many factors.

Progesterone is estrogen's female reproductive partner. Among other functions, progesterone keeps estrogen proliferation at bay to allow for healthy sexual functions. Egg fertilization, ovulation, reproductive organ formation and menstruation would not be possible without this delicate balance.

Though testosterone is an overarchingly male hormone, women do produce it in small amounts to regulate energy, mood and sex drive, and promote healthy bones and muscles. The equilibrium of reproductive hormones is of further importance because the disruption can lead to health issues, such as breast or uterine cancer.

Estrogen plays a diverse set of roles in the human body. It helps create the female reproductive system, including the growth of the mammary gland tissue and ducts. Additionally, it initiates cell proliferation in both the uterus and vagina, improving the chances of pregnancy.

Within the skeletal system, estrogen acts as both a stimulant for long bone growth and growth plate fusion. Estrogen has cardiovascular roles, too: It increases "good" cholesterol high-density lipoproteins (HDLs) and lowers "bad" cholesterol low-density lipoproteins (LDLs), and minimizes the risk of coronary artery disease.

The bulk of estrogen's effects lies within the growth of the reproductive system.

Increases during puberty lead to breast growth and menstruation. It thickens the uterine lining to prepare for egg implantation or, in lieu of that, allows the lining to shed. Throughout gestation, estrogen is released to aid in fetal development.

Meanwhile, estrogen works to maintain sturdy bones by reducing bone reabsorption. Similarly, estrogen regulates cholesterol.

Though it's thought of as a predominantly female hormone, estrogen undeniably impacts males. Abnormal concentrations can lead to a plethora of issues.

An excess of estrogen can lead to conditions such as gynecomastia, which causes an overgrowth of breast tissue. Furthermore, the ability to achieve and maintain an erection is diminished with elevated estrogen levels.

Research has also indicated high estrogen levels in men can negatively affect sperm and testicular function. However, just like for women, estrogen shares the overlapping purpose of heart and bone health upkeep.

Of all the estrogens, ethinyl estradiol is most frequently utilized for contraception because it effectively prevents ovulation during menstruation and thins the uterine lining, thus, removing the possibility of pregnancy. Estrogen preparations come in the form of vaginal rings, transdermal patches and/or oral contraceptive pills (OCPs). The latter often contain a mixture of estrogen and progestin.

If you suspect something may be amiss with your estrogen levels or reproductive health, it is prudent to consult your physician and, if necessary, an endocrinologist.

If you're struggling with menopausal symptoms and lifestyle adjustments aren't cutting it as a solution, you may need hormone replacement therapy (HRT) for deficits. HRT may also be beneficial for people with conditions that impair estrogen production and stability.

How does estrogen affect men?

An excess of estrogen can lead to conditions such as gynecomastia, which causes an overgrowth of breast tissue. Furthermore, the ability to achieve and maintain an erection is reduced.

High estrogen levels in men can negatively affect sperm and testicular function. However, just like with women, estrogen shares the overlapping purpose of heart and bone health upkeep.

What are the different types of estrogen?

There are three primary types of naturally occurring estrogen, all produced at varying levels corresponding to life phases:

• The first type—and most common—is estradiol, which comes from the ovaries and is at its peak during puberty and childbearing years, but production declines with age.
• Next comes estriol, highest during pregnancy and generated within the placenta in preparation for birth and nursing.
• Finally, estrone is created from adipose tissue and is the weakest type, and also the sole form of estrogen made after menopause.

How does estrogen relate to birth control?

Of all the estrogens, ethinyl estradiol is most frequently utilized for contraceptives because it effectively prevents ovulation during menstruation and thins the uterine lining.

Estrogen preparations come in the form of vaginal rings, transdermal patches and/or oral contraceptive pills (OCPs).