The Estrogen Family: Estrone, Estradiol, Estriol

There are three forms of estrogen — estrone, estradiol, estriol — with distinct functions in the female body. Get to know the estrogen family more by reading below.

RELATED: 7 Signs That You Are In Menopause

In this article:

  1. What Is Estrogen?
  2. The Roles of Estrogen in the Female Reproductive System
  3. Estrone, Estradiol, Estriol | Bio-identical Hormone Replacement Therapy
  4. The Estrogen Family
  5. Tips for a Healthy Estrogen Metabolism

The Estrogen Family | Functions, Menopause, and Metabolites

What Is Estrogen?

Estrogens are a group of reproductive hormones promoting the maintenance and development of female characteristics and attributes of the human body. Hormones are chemical messengers which instruct specific tissues to function in a certain way.

Estrogen plays an important role in the formation of female secondary sexual characteristics such as pubic and armpit hair and breasts. They’re also responsible for the regulation of the reproductive system and menstrual cycle.

When a female reaches puberty, the ovaries start estrogen production, triggering her monthly menstrual cycle. During a woman’s menstrual cycle, estrogen creates an environment suited for fertilization, implantation, and nurturing of an embryo.

Estrogen concentration in the body suddenly rises halfway through the cycle signaling the release of an egg (ovulation). After ovulation, estrogen levels decrease.

Estrogen and progesterone are women’s most important sex hormones. The latter helps in maintaining pregnancies and implanting an egg in the uterus.

The Roles of Estrogen in the Female Reproductive System

To further understand the importance of estrogen, let’s break down how it affects different parts of the female reproductive system:


  • Helps in developing the vagina into its adult size
  • Thickens the vaginal wall
  • Increases vaginal acidity to reduce bacterial infections
  • Helps with vaginal lubrication


  • Helps stimulate the growth of an egg follicle

Fallopian Tubes

  • Helps in developing thick, muscular walls in the fallopian tubes
  • Responsible for the contractions needed for egg transport


  • Enhances and maintains the mucous membrane of the uterine lining
  • Increases the size of the endometrium and enhances blood flow, enzyme activity, and protein content
  • Stimulates uterine muscles to develop and contract which helps during delivery of an infant
  • Assists the uterine wall in removing dead tissue during menstruation


  • Regulates uterine mucous secretion thickness and flow to enhance sperm movement and enable fertilization

Mammary Glands

  • Responsible for growth and nipple pigmentation during puberty
  • Stops the flow of milk when the infant is done breastfeeding

Estrone, Estradiol, Estriol | Bio-identical Hormone Replacement Therapy

The collective term estrogen is more commonly known than the more specific hormones which make up this family of chemical messengers. Women undergoing bio-identical hormone replacement therapy may be familiar with these hormones’ names but not with their differences.

Undergoing such therapy requires being proactive in keeping hormones balanced. To do this, knowing how each form of estrogen functions and addressing lifestyle and dietary concerns to support healthy metabolism of estrogen are important.

The Estrogen Family

Estrone (E1)

This is the dominant form of estrogen produced by a menopausal woman. Estrone is primarily created in the fat cells and the liver.

Estrone levels are inversely related to a woman’s estradiol levels. As the ovaries age, estradiol production decreases and estrone concentration in the body rises to make up for the decrease.

A common premenopause complaint is the formation of belly fat. This development of fat helps the body’s estrone production.

This can also be the reason why overweight women tend to have higher estrogen levels and higher estrogen-related conditions like the following:

  • Fibroids
  • Uterine hyperplasia
  • Fibrocystic breasts
  • Gallbladder disease

The majority of estrogens metabolize into a form of estrone. The three major estrone metabolites are:

  1. 2-Hydroxyestrone
  2. 4-Hydroxyestrone
  3. 16-Hydroxyestrone

Metabolites Definition: The end product of metabolism

2-Hydroxyestrone asserts a mild anti-estrogenic effect making it more protective. The other two metabolites are considered mutagenic, meaning they can potentially promote the growth of cancer cells.

Which metabolite forms is dependent on genetic, diet and lifestyle, and liver function. Some women are genetically predisposed to having faulty estrogen metabolism.

Women with such condition need to have their weight in check, eat more cruciferous veggies, and support healthy liver metabolism.

RELATED: HRT Hormone Replacement Therapy For Women: Frequently Asked Questions

Estradiol (E2)

This is the major hormone produced by the ovaries before menopause. It is the most potent of all the forms of estrogen.

This is the hormone responsible for increasing women’s sex drive and moisturizing body mucosal membranes including the skin, eyes, lips, and vagina.

Estradiol strengthens the skin, hair, and bones and helps reduce fine lines from aging. It also increases serotonin levels making women feel more focused and calm.

Depending on genetics, lifestyle, and diet, estradiol metabolizes to one of the estrones listed above.

Estriol (E3)

Out of the three, estriol is the weakest estrogen. Its concentrations in the body are highest during pregnancy when its produced by the placenta.

When not pregnant, the female body creates this hormone in the breast cells and liver from 16-Hydroxyestrone.

Its effects are similar to estradiol’s but are only about 1/8 as strong. Since it binds to the same receptor as estradiol, it is theorized that it acts to balance and modulate the effects of the more potent estradiol.

The majority of beliefs about the effects of this hormone comes from its potential effects during pregnancy. There are studies showing high estriol levels during pregnancy lower breast cancer risks later in life.

Tips for a Healthy Estrogen Metabolism

After learning the distinction among the forms of estrogen, let’s talk about a few tips on how to have healthy estrogen metabolism.

You can measure estrogen metabolites by ordering a 24-hour urine test through your doctor. This will show you your 2-Hydroxyestrone to 16-Hydroxyestrone ratio and assess your estriol and 4-Hydroxyestrone levels.

If results show unfavorable ratios, your doctor may recommend dietary changes and supplements to balance them.

As mentioned, the metabolite we want is 2-Hydroxyestrone. Here are some tips on how to increase 2-Hydroxyestrone.

  1. Eat berries, rosemary, cruciferous vegetables, foods rich in iodine, and flaxseeds.
  2. Have your thyroid checked and get plenty of exercise.
  3. Take estrogen supplements like diindolylmethane (DIM) or indole-3-carbinol (I3C).
  4. Decrease sugar and grains intake.
  5. Eat quality protein and essential fats.

We cannot stress enough the importance of keeping a healthy diet and lifestyle in addressing imbalances and other health conditions. We all have our genetic weaknesses, and it’s only through diet and lifestyle that we can take control of our health.

Do you have any questions about estrogen, estrogen deficiency, or menopause? Let us know in the comments section below!

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