What You Need to Know About Bioidentical Estrogen

what you need to know about bioidentical estrogen

Estrogen has become a household name when it comes to hormones. Many people know that estrogen is the female sex hormone, responsible for keeping menstrual cycles in check and maintaining female sex organ health and function.

What you might not know is that estrogen levels are linked to various health problems and maintaining hormone balance with estrogen and progesterone can help protect you from these problems in later years. Estrogen is a vital hormone for both men and women, and it’s important to know how it functions in your body.

What is Estrogen?

Estrogen is a hormone that plays an essential role development and function of female secondary sexual characteristics, such as breasts, pubic and armpit hair, and the regulation of the menstrual cycle and reproductive system.

Surprisingly, estrogen also plays a role in male reproductive functions. Estrogen in men is essential for modulating libido, erectile function, and spermatogenesis (the production and development of mature sperm). Estrogen receptors, as well as aromatase, the enzyme that converts testosterone to estrogen, are abundant in the brain, penis, and testis, organs important for sexual function.

What Happens to Estrogen During Menopause

During perimenopause (the 8-10 years leading up to menopause), estrogen levels change at an irregular rate. Sometimes there is even more estrogen present in the body than during the childbearing years. This constant ebb and flow of estrogen can cause several uncomfortable symptoms, such as vaginal dryness, hot flashes, night sweats, low libido, and low energy.

During menopause, postmenopause (and post-hysterectomy) stages of a woman’s life, estrogen levels are very low. The body is no longer producing estrogen through the ovaries and therefore many women may experience problems such as:

  • Painful sex due to a lack of vaginal lubrication
  • An increase in urinary tract infections (UTIs) due to a thinning of the urethra
  • Mood swings
  • Hot flashes
  • Breast tenderness
  • Headaches or accentuation of pre-existing migraines
  • Depression
  • Trouble concentrating
  • Fatigue

The Three Types of Estrogen

As explained in our Hormone Series on Estrogen, the term estrogen comes in three forms: Estrone (E1), Estradiol (E2), and Estriol (E3). These three forms of estrogen work in tandem in the body to regulate and control reproductive health in both men and women.

Estradiol (E2)

Estradiol is what we typically think of as “estrogen.” It is the most potent form of estrogen of the three. It also has the greatest effect on the body’s estrogen-specific hormone receptors. Estradiol also stimulates cell growth and proliferation in the uterus (building the uterine wall for childbearing).

Estrone (E1)

Estrone is a form of estrogen and the only type found in women after menopause. Small amounts of estrone are present in most tissues of the body, mainly fat and muscle. The body can convert estrone to estradiol and estradiol to estrone. This form of estrogen is what may cause obese womens’ levels of estrogen to increase during perimenopause.

Estriol (E3)

Estriol is the “weak” form of estrogen and is considered less potent than the estradiol form. However, research has shown that estriol’s weakness may be its strength; estriol (through topical application) does not come with the harmful side effects of traditional estrogen therapy regimes.

Estriol & Bioidentical Hormone Replacement Therapy

Many studies have emerged about why the Estriol (E3) form of estrogen is the preferred choice for bioidentical hormone replacement therapy.

Estriol Does Not Promote Cell Growth

The concerns surrounding estrogen hormone therapy stem from the estradiol form of estrogen. Estradiol is the most potent form, and causes cell growth in areas such as the breasts and uterine lining. This cell growth in women who have been through menopause or a hysterectomy is implicated in problems like cancer and endometriosis.

Estriol, however, does not appear to increase the risk of hormone-dependent cancers of the breast or endometrium (uterine lining) when administered topically(1-3).

Estriol Offers Estrogen Metabolism Benefits

An interesting feature of the estriol form of estrogen is that it actually increases estrogen metabolism when used in conjunction with a smaller amount of estradiol. According to a study(2), scientists investigated a mixture of both stimulating and non-stimulating effects posed by estriol upon estrogen receptors.

It was found that when estriol is given topically together with estradiol, the estradiol-specific stimulation to cells is decreased. This breakthrough discovery helped to explain how estriol actually reduces the cancerous effects of estradiol. It was also shown that estriol can have pro-estrogenic effects when given alone over a long period of time, which explains why menopausal women achieved symptom relief after taking bioidentical estriol by itself. The optimal ratio is 80% estriol to 20% estradiol.

Get Help with Estrogen Balance with Dr. Randolph

If you’re suffering from the side effects that result from low estrogen, we can help. At Dr. Randolph’s Ageless Wellness Center, we have decades of experience in hormone replacement therapy and offer a wide range of products services designed to help you reach and maintain hormone balance. Bi-Est, our newest estrogen cream, is specifically formulated to offer the best 80/20 balance of estriol and estradiol that maximizes the health benefits of estrogen.


1. Takahashi K, Okada M, Ozaki T, et al. Safety and efficacy of oestriol for symptoms of natural or surgically induced menopause. Hum Reprod. 2000 May;15(5):1028-36.

2. Melamed M, Castano E, Notides AC, Sasson S. Molecular and kinetic basis for the mixed agonist/antagonist activity of estriol. Mol Endocrinol. 1997 Nov;11(12):1868-78.

3. Weiderpass E, Baron JA, Adami HO, et al. Low-potency oestrogen and risk of endometrial cancer: a case-control study. Lancet. 1999 May 29;353(9167):1824-8.