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Three Types of Oestrogen: Estrone, Oestradiol, And Estriol

Most of us are familiar with oestrogen as the primary female sex hormone, but this substance does much more than manage menstrual and reproductive health. From the formation of bones and organs to the regulation of digestion and cognition—oestrogen is involved in all aspects of our lives.

Image showing three types of Oestrogen: Estrone, Oestradiol, and Estriol.

Did you know there is more than one type of oestrogen? Have you considered the role oestrogen plays in the male body? Most of us have heard of this hormone but this time we’ll dig a little deeper, looking at the three different oestrogens and their functions in both males and females.


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Why do we need oestrogen?

You may be surprised to learn that oestrogen is important for all people, not just for women, and is active in the body long before puberty. From the moment of conception, oestrogen plays a crucial role in how our bodies develop. In both men and women, this hormone supports the growth and maintenance of fundamental physiological systems, including:

Bone health

Oestrogen is necessary for developing and maintaining bone strength and density. It is a key factor in closing healthy bone growth plates in adolescent boys and girls. The interaction of oestrogens with testosterone and other hormones regulates bone remodelling—the balance between bone formation and resorption—to maintain skeletal health in men and women. Reduced oestrogen levels post-menopause put women at greater risk of osteopenia and osteoporosis.

Cardiovascular health

Oestrogen supports and protects healthy blood vessel function, regulates cholesterol levels, and reduces the risk of cardiovascular disease in men and in pre-menopausal women. Studies have shown that supplementing oestradiol in menopausal women can reduce their risk of heart disease, but how long it is safe to do so remains controversial.

Brain function

Oestrogen influences mood, cognition, and memory. Research indicates that oestrogen protects the brain against cognitive decline and neurodegenerative diseases in both men and women as we age.

Metabolic regulation

Oestrogen affects insulin sensitivity, lipid metabolism, and glucose metabolism. It also helps regulate energy expenditure, body weight, and fat distribution (which differs in males and females).

Skin health

Oestrogen stimulates collagen and other dermal components to maintain skin hydration, elasticity, and thickness. Maintaining normal oestrogen levels promotes skin health and can delay signs of aging.

Image illustrating the unique function of estrogen in the female body.

The special role of oestrogen in the female body

Reproductive health

Your ovaries, uterus, and fallopian tubes develop in utero and maintain their function due to the presence of oestrogen. This hormone also supports sexual health by maintaining vaginal lubrication and elasticity.

Secondary sexual characteristics

With the onset of puberty, the ovaries start producing oestrogen, so levels increase dramatically in adolescent girls resulting in breast growth, widening of the hips, pubic hair, and the redistribution of body fat.

Menstrual cycle regulation

Oestrogen regulates the menstrual cycle by stimulating the growth of the uterine lining during the follicular phase. Because oestrogen is involved in so many of the body’s systems, many women feel physical symptoms and emotions as hormone levels fluctuate during the different stages of the cycle. For example, when oestrogen is at its peak (around mid-cycle), you may feel you are at your best—social, active, and energetic. As levels decline in the second part of the cycle, you might feel more introverted, tired, and calm.

The special role of oestrogen in the male body

Libido and sexual function

Oestrogen influences sex drive and erectile function in men. While testosterone is the main hormone responsible for male sexual characteristics, small amounts of oestrogen are crucial for healthy sexual function in men. In women it is the reverse—oestrogen generates female sexual characteristics, but a little testosterone is needed for a healthy libido.


Oestrogen is one of several hormones involved in sperm production. Oestrogen receptors are abundant in the male reproductive tract. What we once thought of solely as a “female hormone”, we now know is essential for healthy male fertility as it maintains the structural integrity of the testes and supports the maturation and development of sperm cells.

What are the three types of oestrogen?

Now that we’ve covered some of the functions of oestrogen, let’s take a look at the variations of this hormone. There are three main types of oestrogen: oestradiol—the most powerful and abundant form, estriol—important during pregnancy, and estrone—the predominant form after menopause.


Oestradiol (E2) is the most potent and active form of oestrogen in the human body. In women around 90% is produced in the ovaries, but small amounts are also made in the adrenal glands and fat cells.

In men, only about 20% of circulating oestrogens are produced in the testes, particularly in the Leydig cells, while the rest is produced locally in adipose, brain, skin, and bone cells where testosterone is converted into oestradiol by the action of aromatase.

Oestradiol is the most abundant form of oestrogen in women throughout their developmental and reproductive years. It is responsible for regulating the menstrual cycle and supporting fertility. It also helps develop and maintain female sexual characteristics such as breast growth and hip rounding. Oestradiol is also the main oestrogen responsible for bone health, mood, energy, and skin.

Adult men produce something like one tenth the oestradiol adult women produce. Even so, these tiny amounts are crucial for reproductive health and bone density.


Estriol (E3) is the weakest form of oestrogen that is most abundant during pregnancy when it is produced in the placenta to support pregnancy and foetal development. Its effects are similar to those of oestradiol but only about 1/8th as potent.

Estriol helps maintain the uterine lining, supports the growth and development of the foetus, and prepares the breasts for lactation.

During pregnancy, estriol levels increase steadily and peak in the third trimester. Estriol levels are sometimes measured to assess the health of the foetus as part of prenatal screening tests. After childbirth, once the placenta is delivered, estriol levels drop rapidly.

Non-pregnant women metabolize small amounts of E3 in their breast cells and liver.


Estrone (E1) is the predominant form of oestrogen in menopausal women. As the ovaries age and decrease their oestradiol production, estrone production in the liver and fatty tissues increases to make up the difference.

Many older women complain of belly fat. Even if you’d rather still have a snatch waist, a little extra belly helps with estrone production, which is generally a good thing.

As always, diet, exercise, lifestyle, and genetics influence and moderate how our body systems work.

Visual representation of the effects of excess oestrogen production in the body.

What happens when your body produces too much oestrogen?

Regardless of the oestrogen type, too much of it can have negative effects on your body. Here are some of the symptoms of high oestrogen, or oestrogen dominance.

  • irregular periods and breakthrough mid-cycle bleeding
  • breast tenderness, swelling, and discomfort
  • mood swings, irritability, anxiety, or even depression
  • bad PMS
  • heavy periods with clots
  • uterine fibroids
  • fibrocystic breast lumps
  • weight gain—particularly around the hips, thighs, and abdomen
  • low energy
  • decreased sex drive
  • headaches and migraines
  • bloating, fluid retention in the hands, feet, or ankles
  • difficulty sleeping

What to do when you have too much oestrogen

You won’t be able to diagnose oestrogen dominance just by counting symptoms. The only way to find out for sure is to have your hormone levels tested. If the results show that your oestrogen levels are too high, there are steps you can take to manage this.


Keep fit

Because oestrogen is metabolized in adipose tissue, excess body fat can lead to higher oestrogen levels. Maintaining a healthy weight through regular exercise and a balanced diet can help regulate hormone levels.

Eat well

Eat a diet rich in fruits, vegetables, whole grains, and lean proteins. Limit processed foods, sugars, and saturated fats, as these can contribute to hormonal imbalances. Eat fewer foods naturally high in phytoestrogens, such as soy, flaxseeds, and liquorice root. Studies have shown that women who eat a vegetarian diet have 15–20% lower serum oestrogen levels.

Manage stress

Chronic stress can disrupt hormone balance. Techniques such as meditation, yoga, deep breathing exercises, and mindfulness can help manage short-term stress, but chronic stress is more complicated. How you manage it will depend on what your stressors are. If work has been driving you crazy, try taking a short vacation or setting clear boundaries. If you’re stressed at home, dividing the household chores with your partner and kids could reduce the pressure.

Limit alcohol and caffeine

Excessive alcohol and caffeine consumption can interfere with hormone metabolism and worsen oestrogen dominance. Both alcohol and oestrogen are metabolized, or broken down, in the liver. Overloading the liver reduces its effectiveness and can lead to all sorts of problems down the line.

Avoid endocrine disruptors

Endocrine disruptors are substances in the environment that act like hormones when they get inside the body. Minimize your exposure to environmental toxins and endocrine-disrupting chemicals like BPA and phthalates that are used in plastics, pesticides, and some personal care products.

Last resort: medication

In some cases, your doctor may recommend medications such as aromatase inhibitors or birth control pills to regulate oestrogen. However, small lifestyle changes can have significant positive effects so try some of those first.

What happens when your body doesn’t produce enough oestrogen?

Symptoms that might indicate low oestrogen are:

  • irregular or missing periods
  • hot flashes and night sweats
  • vaginal dryness
  • dry skin
  • weak bones and susceptibility to bone fractures
  • mood changes similar to those with high oestrogen
  • poor sleep
  • decreased libido and pain during sex
  • fatigue
  • brain fog

Some of the reasons why your oestrogen might be low include:


The most common cause of low oestrogen in women is menopause, which typically happens around the age of 45 to 55. As a woman’s reproductive period comes to an end, the ovaries gradually decrease their oestrogen production.

Ovary removal

Surgical removal of the ovaries, or oophorectomy, causes an abrupt decrease in oestrogen production.

Primary ovarian insufficiency

Also known as premature ovarian failure, POI is when the ovaries stop functioning before the age of 40, leading to decreased oestrogen production.

Extreme weight loss

Excessive exercise, poor nutrition, and eating disorders such as anorexia nervosa can lead to low body weight and too little fat. This disrupts hormone production in the adipose tissues and can lead to low oestrogen levels.

Certain medications

Some medications, such as certain chemotherapy drugs, hormonal therapies, or drugs used to treat conditions such as endometriosis or uterine fibroids, can suppress oestrogen production and lead to low oestrogen levels.

Hypothalamic or pituitary disorders

Conditions that affect the hypothalamus or pituitary gland, such as hypopituitarism or hypothalamic amenorrhea, can affect oestrogen production and regulation.

What to do when you don’t have enough oestrogen

Just like with oestrogen dominance, you first need to test your levels. If the results confirm low oestrogen, you have options.

Hormone replacement therapy

Hormone replacement therapy (HRT) uses either synthetic or bioidentical supplements to increase hormone levels. Whether one form is safer or superior to the other is still being studied. The method of delivery is also varied. Oestrogen comes in pills, patches, creams, gels, and vaginal rings. Each method has a slightly different effect, with greater significance between topical methods and pills that have to pass through the digestive tract. Consult your doctor or an endocrinologist for a personalized recommendation.

Lifestyle changes

Regular exercise, a balanced diet, adequate sleep, stress management, and avoiding excessive alcohol and tobacco use can help support hormonal balance and your overall well-being.

Dietary supplements

Phytoestrogens are naturally present in many of the foods we eat, but plant-derived compounds are also sold as supplements to help increase oestrogen. Herbal remedies like black cohosh or red clover are also sometimes recommended. Although data on the effectiveness of such natural remedies is limited, they are generally safe to try. Consult with your doctor before trying a new supplement to be sure that your body can tolerate it.

Treatment of underlying conditions

Underlying conditions, such as thyroid disorders, pituitary dysfunction, and eating disorders all influence oestrogen production. Healing other conditions can help bring your hormones back into balance.

Final words

Hormones are powerful and deserve our respect. These magical substances secreted in tiny amounts by our tissues and glands have an enormous effect on how we feel and how our bodies function. We hope that this article helped you understand oestrogen a little better.

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