All About Estrogen

Written by Lindsay Christensen, MS, CNS, LDN

Estrogen is often considered the quintessential “female” hormone. However, what we refer to as “estrogen” is actually a family of three types of estrogens – estradiol, estrone, and estriol. Healthy, balanced, age-appropriate estrogen levels are essential for whole-body wellbeing in women both in their reproductive years and the perimenopausal period. Read on to learn about the different forms of estrogen, their roles in the body, the consequences of estrogen imbalances, and how to maintain healthy estrogen levels.

What Is Estrogen and Why Is It Important?

Estrogen comes in three different “flavors” – estradiol, estriol, and estrone. Each form of estrogen has unique effects on the body; however, the body can also interconvert one estrogen into another through enzymatic processes.

Estrone (E1)

Estrone is the main form of estrogen present in menopause; it has much weaker effects on the body compared to estradiol. Estrone is broken down in the body into metabolites, including 2-hydroxyestrone, 4-hydroxyestrone, and 16-hydroxyestrone. Excessive amounts of 16-hydroxyestrone can promote aberrant growth of estrogen-sensitive tissues, and may contribute to the development of estrogen-sensitive breast cancer. (1) Excessive 4-hydroxyestrone can damage DNA. (2) 2-hydroxyestrone is considered the most beneficial or “safe” estrone metabolite.

Estrone is made by women of all ages. It continues to be made by women after menopause.

Estradiol (E2)

Estradiol is the main form of estrogen made in the bodies of non-pregnant premenopausal women. Estradiol is also the most prevalent form of estrogen in men. While both male and female bodies create estradiol, women of reproductive age have much higher estrogen levels than men due to estrogen production by developing follicles in their ovaries. (3)

Estradiol levels decline significantly after menopause as the ovaries cease their production of follicles. Low estradiol levels may contribute to low libido, depression, vaginal dryness, and low libido in menopausal women.

Estriol (E3)

Estriol is the dominant form of estrogen present in the female body during pregnancy. Levels of estriol are usually low in women who are not pregnant. Estriol levels are the highest right before childbirth.

Where Is Estrogen Made?

In premenopausal women, estradiol is released in the ovaries by a developing follicle, a small fluid-filled sac containing an immature egg in the ovary. In perimenopausal women, estradiol levels fluctuate wildly due to variations in ovarian activity. Ultimately, estrogen levels decline permanently in the postmenopausal period. Estradiol is also made in fat tissue in both premenopausal and perimenopausal women. (4)

Estrone is made in the ovaries, adrenal glands, and fat tissue. Last but not least, we have estriol. In non-pregnant women, estriol is made only in minute quantities and not in the ovaries; instead, it is synthesized by the biochemical conversion of estradiol and estrone into estriol by a set of liver enzymes called cytochrome P450 enzymes. During pregnancy, on the other hand, estriol is synthesized in significant amounts by the placenta.

In men, estrogens are made in several tissues, including the testes, brain, and fat tissue. (5)

The Pros and Cons of Estrogen: The Amount Matters!

In the right amounts, estrogen has positive effects on the health and function of both men and women’s bodies. However, excessive amounts of estrogen can adversely affect our health.

First, some of the positive benefits of estrogen include:

  • Improved insulin sensitivity, or the ability of the body’s cells to use glucose for fuel (6)
  • Healthy joint and muscle function (7)
  • Supports brain health, including focus and attention (8)
  • Supports libido in women (9)
  • Supports libido, spermatogenesis (sperm formation), and erectile function in men (10)
  • Promotes a healthy mood: According to female hormone expert Dr. Lara Briden, estradiol is a woman’s “happy hormone” that stimulates mood and libido by boosting serotonin. Insufficient estrogen levels may thus contribute to a low mood and libido in premenopausal women and to a higher sensitivity to stress and depression during the menopause transition. (11)
  • Optimizes bone density, promoting a strong skeletal system (12)
  • Promotes a healthy cardiovascular system: Estrogen modulates vascular function, reduces oxidative stress, and influences enzymes that regulate cholesterol levels inside the body, supporting cardiovascular health. (13, 14)
  • Supports youthful, supple skin (15)
  • Promotes restful sleep (16)

The adverse effects and symptoms of excess estrogen, or a relative excess of estrogen in relation to progesterone, the other primary female sex hormone, include:

  • Menstrual irregularities, such as heavy periods (17)
  • Endometriosis (18)
  • Aberrant growth of estrogen-sensitive tissues, such as fibroids and breast cancer (19)
  • A tendency towards weight gain
  • Gynecomastia, or breast tissue growth, in men

Primary symptoms of low estrogen include:

  • Hot flashes
  • Night sweats
  • Brain fog and cognitive decline
  • A decrease in bone density
  • Low libido in men and women
  • Low mood
  • High cholesterol, particularly in menopausal and post-menopausal women
  • Disrupted sleep
  • Skin aging
  • Insulin resistance: Insulin resistance due to low estrogen occurs primarily in the postmenopausal period.

Diet and Lifestyle Changes and BHRT Support Healthy Estrogen Levels

Several dietary and lifestyle strategies balance estrogen levels, including:

  • Eating plenty of bioavailable protein. The bioavailability of protein refers to how well it is digested in the gastrointestinal tract. Bioavailable proteins are efficiently broken down in the gut, and their amino acids are efficiently utilized to support various bodily processes, including tissue repair. Without adequate protein, the body cannot make enzymes to detoxify estrogen. Including meat, poultry, seafood, and eggs in your diet, which are the most bioavailable source of protein, will ensure that you can make estrogen-detoxifying enzymes.
  • Avoid eating an entirely plant-based diet. A 100% plant-based diet is devoid of fat-soluble vitamins A and D and cholesterol. The lack of these nutrients can make it difficult for your body to create sufficient estrogen since cholesterol is the backbone for estrogen (and other steroid hormones). You need fat-soluble vitamins for hormone synthesis. You don’t need to eat a carnivore diet to make estrogen; just make a concerted effort to incorporate animal foods, such as eggs, fish, grass-fed beef, and dairy, if you tolerate dairy products.
  • Avoid excessive alcohol intake. High intakes of alcohol can increase estrogen synthesis and promote estrogen dominance. (20)
  • Avoid xenoestrogens. Xenoestrogens are compounds that imitate estrogen. Many xenoestrogens are chemicals added to consumer products, such as the plasticizer “phthalate” added to personal care products. In certain foods such as soy and hops, xenoestrogens also come in the form of phytoestrogens or plant compounds with estrogenic properties. (21)
  • Eat cruciferous vegetables. Cruciferous vegetables contain phytochemicals such as diindolylmethane (DIM) that promote healthy estrogen metabolism. (22)
  • Support your gut health. A significant amount of estrogen metabolism occurs in your gut. (23) If your gut health is out of whack, you may have more estrogen circulating in your system, contributing to estrogen dominance symptoms.

Bioidentical Estrogen Replacement Therapy

For decades, female hormone replacement therapy (HRT) involved administering Premarin. This estrogen drug contained a variety of conjugated estrogens, none of which are bioidentical or identical to the body’s own estrogens. Two of the main hormones in Premarin are estrone sulfate and equilin sulfate, with the latter estrogen derived from horses. Large-scale studies have found that Premarin can be dangerous to the breasts and heart. It increases the risk of blood clots, heart disease, and breast cancer, mainly because it is taken orally, which requires all hormones to be processed by the liver, placing a heavy demand on this organ of detoxification. (24, 25)

Conversely, bioidentical transdermal estradiol is estradiol with a structure identical to the body’s own estradiol. It is derived from yams and is typically administered topically or intravaginally. Because it is applied topically, bioidentical estradiol can enter the blood circulation quickly and doesn’t need to be processed by the liver. Research shows that bioidentical estradiol may improve emotional lability, anxiety, irritability, and vasomotor symptoms, such as night sweats, in women. (26) For perimenopausal and postmenopausal women, bioidentical estradiol may be most effective when paired with bioidentical progesterone.


Estrogen is a crucial hormone essential for health and vitality in women. Estrogen is truly a “Goldilocks” hormone; we don’t want too much or too little. By maintaining a healthy balance of estrogen in the body through nutrition and lifestyle changes, and BHRT, we can reap the benefits of estrogen for the brain, bone, reproductive, and metabolic health without the proliferative and inflammatory downsides of excess estrogen.

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