Estrogen: Friend or Foe? What You Need to Know



Jessica T. Wei, MD, FACOG

Hormones, hormones, hormones! What is a woman to do? Is estrogen my friend or my foe? And what can I do to balance my hormones so that estrogen remains my friend for life?



Estrogen is a sex steroid hormone derived from cholesterol, as all steroid molecules are. Estrogen is responsible for the growth and development of female sexual characteristics and reproduction, as well as supporting bone, brain, cardiovascular, skin, bladder, and vaginal health, among so many other important processes in the body. So, we need estrogen!

When we speak about estrogen we are often primarily referring to a form of estrogen called estradiol, which is the predominant estrogen produced by the ovaries prior to the time a woman experiences menopause. There are two other forms of estrogen: estrone, which is predominant after menopause; and estriol which is a much less potent hormone than estradiol, and present in higher levels during pregnancy.

Estrogens act differently in various areas of the body by either stimulating or inhibiting activity in those areas. This depends on what type of receptor is present in that tissue. There are two types of receptors: alpha and beta receptors.

  • Alpha-receptor rich tissue is found in the breast, endometrium (lining of the uterus), and ovary, and generally when stimulated will promote cell-division and growth. Overstimulation can eventually lead to cancer.
  • Beta-receptor rich tissue is found in the brain, bone, endothelium (blood vessels), intestinal mucosa, and prostate.

Understanding this concept of different estrogen receptors enables us to understand that the effects of estrogen throughout the body are varied, and we cannot uniformly say that estrogen is bad or good. What we can say is that excess estrogen out of balance can cause significant health issues such as:

  • Heavy and painful periods
  • PMS
  • Infertility
  • PCOS (polycystic ovarian syndrome)
  • Fibroids
  • Endometriosis
  • Bone loss
  • Cognitive issues
  • Cardiovascular disease
  • Hormonally-related cancers such as breast, uterine, and ovarian cancer.



Basically, excess estrogen imbalance (also described as “estrogen dominance” relative to levels of progesterone) arises from four causes:

  1. Increased exposure to the body;
  2. Increased production by the body;
  3. Decreased balancing effects from progesterone within the body;
  4. Decreased elimination from the body.

Let’s look at each of these more closely, and understand that each is dependent on the others to create imbalance or balance. In other words, imbalance is created from multiple causes and conditions.

Increased exposure of estrogen or estrogen-like substances to the body

The most obvious source of increased exposure is taking synthetic estrogen or bioidentical estrogen in the form of oral contraceptive pills or hormone replacement. Although taking synthetic hormone (estrogens and progestins) can provide a convenient form of birth control and some symptomatic relief from issues such as heavy, painful periods and hot flashes, they also have significant negative effects for many women. These negative effects of synthetic estrogen intake can include:

  • Increased risk for depression and mood changes;
  • Depletion of vitamins and minerals (specifically vitamins B2, B6, B12, C, and E, as well as magnesium, selenium, and zinc);
  • Increased risk of developing blood clots;
  • Metabolic changes including weight gain, insulin resistance, and adverse changes in cholesterol and triglyceride levels.

Another common source is the food which we eat, primarily conventional meat and dairy. Since the 1950’s, the FDA has approved the use of natural and synthetic estrogen, progesterone, testosterone, and growth hormone to allow for faster weight gain and production of meat and dairy.

We also now have exposure to excessive amounts of xenoestrogens, toxins which have estrogenic effects in the body. These xenoestrogens are endocrine (hormone) disrupting chemicals (EDC’s), which often bind more strongly to the estrogen receptor than estrogen itself leading to overstimulation of the receptor or blocking of the normal signaling by that hormone. EDC’s can also interfere the detoxification and elimination of hormones by the liver. Some common EDC’s which have estrogenic effects are:

  • Bisphenol A (BPA) found in can liners, receipt paper, and plastics;
  • Polybrominated diphenyl ethers (PBDE’s) found in flame retardants and house dust;
  • Dioxins formed as an unintentional by-product of many industrial processes involving chlorine such as waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching;
  • Perfluorinated chemicals (PFC’s) found in nonstick cookware and water-resistant coatings;
  • Polychlorinated biphenyls (PCB’s) found in coolants and lubricants;
  • Diethylstilbestrol (DES) given to pregnant women from the 1941 to 1971 to prevent pregnancy complications and pregnancy loss, now known to cause increased risk for gynecologic problems including vaginal cancer in the daughters of women exposed to DES in utero. (DES exposure can also cause significant medical problems in “DES sons” as well.)



Estrogen (specifically estradiol) is made from testosterone in the body via an enzyme called aromatase. The activity of aromatase is stimulated by:

  • High levels of inflammation;
  • Excess body fat;
  • high insulin levels (insulin resistance);
  • alcohol.

The aromatase enzyme is found in many tissues throughout the body: ovary, brain, fat, blood vessels, skin, and bone, as well as in tissue of endometriosis, uterine fibroids, breast cancer, and endometrial cancer. After menopause, most estrogen is produced in areas outside of the ovary, most notably in excess body fat. Drugs which block the activity of aromatase are used to treat breast cancer. Inappropriately increased aromatase activity leads to excess circulating estrogen in the body.

Free (active) estrogen levels in the body can also result from decreased levels of binding to a carrier protein in the blood called SHBG (sex-hormone binding globulin). Decreased SHBG levels are associated with obesity, elevated insulin levels, steroid use, hypothyroidism, and elevated testosterone levels.



Progesterone is another sex steroid which balances the effects of estrogen in the body. Progesterone levels rise in the second half of the menstrual cycle after ovulation to decrease estrogen levels and stabilize the lining of the uterus to prevent irregular or excessive bleeding. If pregnancy occurs during that cycle, progesterone rises dramatically to support the growth of the fetus. Progesterone is primarily produced by the ovary, in smaller amounts by the adrenal glands, and in large amounts by the placenta during pregnancy. It has multiple physiologic effects including decreasing estrogen receptor activity and blocking the production of estrogen at the DNA level. Thus, conditions that decrease progesterone relative to estrogen or block the activity of progesterone at its cellular receptor can contribute to estrogen imbalance. These include:

  • Inflammation;
  • Polycystic ovarian syndrome (PCOS);
  • Excess cortisol levels (from excess stress);
  • Decrease in ovulatory cycles in the years approaching menopause (i.e., “perimenopause” which on average occurs at age 46);
  • Hypothyroidism;
  • Inappropriately elevated levels of the hormone prolactin, responsible for breast milk production after childbirth.



Detoxification and elimination of hormone and toxins occurs primarily in the liver and in the gut, through a process of called biotransformation.  Biotransformation is the conversion of toxic substances into non-toxic substances by making them water-soluble to be excreted in stool and urine. The capacity of the body to detoxify is dependent on many different enzymes, nutrient cofactors needed for function of those enzymes, and healthy gut bacteria.

In the liver, the transformation of estrogens has 2 phases:

  1. Phase One detoxification involves three primary “highways” down which estrogen can travel. The most favorable route converts estrogen to a metabolite called 2-hydroxy estrone. The less favorable routes lead to products called 4- and 16- hydroxyestrone. Higher 4-hydroxy estrone levels are associated with direct DNA damage and progression to cancer.
  2. Phase Two detoxification involves a process called methylation, which essentially neutralizes the 2- and 4- hydroxy estrone products.

Thus, anything we can to do increase 2-OH estrone, decrease 4-OH estrone, and enhance balanced methylation will lead to proper estrogen balance. These estrogen metabolites can be measured in the urine.

In the gut, there are 100 trillion bacteria which help to protect the body from infection and disease. When the gut “microbiota” become imbalanced, there can be increased production of an enzyme called beta-glucuronidase. Beta-glucuronidase allows estrogen which is marked for excretion through the stool to be recycled back into the body. Thus, elevated beta-glucuronidase levels can be associated with elevated estrogen levels, as less estrogen is eliminated from the body. Beta-glucuronidase levels can be evaluated with stool testing.



So much! If we consider the multitude of causes and conditions for imbalance, we can then focus on the important aspects of creating and maintaining healthy estrogen levels.

These are the basic steps:

  • Eat a largely plant-based anti-inflammatory organic whole food diet to give your body the key nutrients and information it needs to function optimally;
  • Eat cruciferous vegetables to stimulate the production of the favorable 2-OH estrone metabolite in the liver;
  • Reduce toxin exposure as much as possible from processed foods, hormonally-treated meats and dairy products, unfiltered water, plastics, beauty and personal care products (look up the “Dirty Dozen Endocrine Disruptors” from the Environmental Working Group);
  • Maintain an ideal body weight to decrease excess body fat and insulin resistance;
  • Optimize gut health with pre- and probiotic foods to support good gut bacterial balance;
  • Avoid alcohol or moderate alcohol intake to two or less drinks/week;
  • Consider natural progesterone supplementation or chaste tree extract (Vitex agnus castus) to enhance progesterone activity;
  • Consider non hormonal forms of contraception such as an IUD, diaphragm, or Fertility Awareness Method (if you have very predictable regular menstrual cycles);
  • Consider consulting with a functional medicine practitioner to explore issues with sex hormone metabolism, GI and detoxification issues. Specialty testing can provide personalized and in-depth information about what specifically is causing imbalance for you, and provide an individual roadmap to restore the intended balance and rhythm of your body.



Whoa! That was quite a ride we took to explore the beautiful intricacies of estrogen. My hope is that we realize that our bodies have so much complexity to help balance our physiology and that there is so much that we can do to influence all of it to achieve optimal health and well-being. If we take the time and effort to care exquisitely for this body we have been blessed with, estrogen will be our friend for life.




Dr. Wei

Jessica Wei, MD, FACOG is a board-certified Ob/Gyn and functional medicine practitioner, who left her private practice of thirteen years to create the women’s functional medicine practice, Women’s Holistic Health, LLC in West Hartford, Connecticut.  To augment her extensive conventional training, Dr. Wei completed a fellowship in Integrative Medicine at the University of Arizona Center for Integrative Medicine founded by Dr. Andrew Weil, the internationally recognized expert in integrative medicine. She also completed the Kalish Method Functional Medicine Mentorship, and is obtaining certification with the Institute of Functional Medicine with expertise in the areas of hormonal, GI, immune, energetic, and cardiometabolic health, as well as detoxification. She specializes in the evaluation and treatment of hormonal issues such as PMS, PCOS, fibroids, endometriosis, and menopausal issues, as well as fertility, fatigue, digestive problems, thyroid issues, and depression/anxiety.


Women’s Holistic Health, LLC is located at 18 North Main Street, 3rd floor in West Hartford. For more information, please visit: www.jessicaweimd.com;  or e-mail info @jessicaweimd.com; or call 860-904-9728. Dr. Wei looks forward to hearing from you!

If you are interested in talking with Dr. Wei about hormonal imbalance, please schedule a free 15-minute telephone consultation at www.calendly.com/drwei.

Jessica Wei, MD

Owner and Certified Functional Medicine Physician Women’s Holistic Health, LLC

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Women's Holistic Health, LLC

18 North Main Street, West Hartford, CT • 860-904-9728

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