Estrogen is a powerful hormone. We don’t want too little (see Part 1: Estrogen Deficiency), but we definitely don’t want too much.
The many types of estrogen
The tricky thing about estrogen is that it’s not one thing—it’s many different things.
- There is estradiol, the main (and best) estrogen from our ovaries.
- There’s also estrone from body fat and estrogen metabolites from intestinal bacteria.
- There are xenoestrogens or endocrine disrupting chemicals (EDCs), which are environmental toxins that act like estrogen.
👉 Tip: The estrogen in birth control (ethinylestradiol) is a xenoestrogen.
- Finally, there are plant estrogens (phytoestrogens), which generally have an anti-estrogen effect in young women. Read How Soy Affects Hormones.
Causes of estrogen excess
1) Hormonal birth control
The estrogen in hormonal birth control is a xenoestrogen called ethinylestradiol. It’s stronger than the body’s own natural estradiol and damages gut bacteria so it impairs estrogen metabolism or detoxification.
2) Impaired metabolism or detoxification
All estrogens (including xenoestrogens) must be detoxified in a two-step process through the liver and bowel.
Step 1 is liver conjugation which requires B-vitamins, selenium, and the amino acid glycine. Liver conjugation is impaired by xenoestrogens and by alcohol, which is why alcohol causes measurably higher blood levels of estrogen and an increased risk of breast cancer.
Step 2. Conjugated estrogens enter the bowel, where they should then exit the body. When healthy gut bacteria are present, they assist with the safe removal of conjugated estrogens. When unhealthy bacteria are present, they impair estrogen metabolism by making an enzyme called beta-glucuronidase, which deconjugates and reactivates estrogen. The reactivated estrogen is then reabsorbed into your body by a process called enterohepatic recirculation or “gut-liver recirculation.” The result is estrogen excess. That’s why antibiotics can cause or worsen PMS.
Estrogen can triple during the years before menopause. And it’s erratic. It swings from low to high, and back to low again. I call this the perimenopausal estrogen roller coaster. Roller coaster symptoms include the hot flushes and insomnia of estrogen deficiency, plus the breast pain and irritable mood of estrogen excess.
👉 Tip: At its highest point, serum estradiol should not exceed 270 pg/mL (1000 pmol/L).
Body fat makes an estrogen called estrone which can be a problem with polycystic ovarian syndrome (PCOS). After menopause, too much estrone can increase the risk of uterine cancer.
5) Histamine and mast cell activation
Estrogen stimulates mast cells to make more histamine and estrogen down-regulates the DAO enzyme that you need to clear histamine. At the same time, histamine stimulates the ovaries to make more estrogen. The net result is a vicious cycle of:
estrogen → histamine → estrogen → histamine.
For many women, symptoms of “estrogen dominance” such as PMS, period pain, and heavy periods improve by avoiding cow’s dairy and other histamine-reducing strategies. Read The Curious Link Between Histamine Intolerance and Estrogen.
6) Receptor hypersensitivity
The actual amount of estrogen is only part of the story. What matters more is your response to estrogen and that happens at the estrogen receptors in the brain, bowel, thyroid, and muscle. They’re stimulated by estradiol. They’re also stimulated by reabsorbed estrogens and xenoestrogens.
Your estrogen receptors become more or less sensitive depending on different factors.
- Receptors become more sensitive in the presence of chronic inflammation or histamine, which is why inflammatory foods like dairy cause period problems. They become more sensitive there’s not enough iodine (read Why I prescribe iodine for PMS, breast pain, and ovarian cysts.).
- Receptors become less sensitive when they’re sheltered by the phytoestrogens from legumes, nuts, and vegetables.
As a teen, your estrogen receptors are naturally more sensitive and that can cause heavy periods. The estrogen excess of the teenage years should settle down after a year or two, and in the meantime, there are simple non-hormonal ways to reduce menstrual flow. See Chapter 9 of my book and also my Heavy Period post.
What is estrogen dominance?
Estrogen dominance usually means too much estrogen, but it can also describe a situation of normal estrogen and too little progesterone.
I don’t like the term “estrogen dominance” because I prefer the more precise terms of estrogen excess and progesterone deficiency. It’s possible to suffer both conditions simultaneously. Read Why I Don’t Use the Term Estrogen Dominance.
Endometriosis is not a hormonal condition and is not caused by estrogen. Instead, it’s an inflammatory disease that is affected by hormones. Read Endometriosis: 5 Natural Treatments That Really Work.
How to reduce estrogen
- Don’t take hormonal birth control.
- Avoid cow’s dairy and employ other strategies to reduce histamine.
- Reduce alcohol to promote the healthy metabolism or detoxification of estrogen.
- Eat vegetables to promote liver conjugation, feed healthy intestinal bacteria, and shelter estrogen receptors (phytoestrogens).
- Avoid antibiotics to maintain healthy intestinal bacteria.
- Maintain a healthy body weight to reduce the production of estrone.
- Avoid inflammatory foods such as dairy to reduce histamine and hypersensitivity of the estrogen receptors.
- Reduce exposure to xenoestrogens such as plastics and pesticides.
Best supplements to lower estrogen
- Calcium d-glucarate. Glucarate is a small molecule that’s made by the body and is found in foods such as oranges and broccoli. It assists with estrogen detoxification in two ways. First, it binds to estrogen in the liver and deactivates it. Second, it inhibits beta-glucuronidase, which is the enzyme made by gut bacteria that causes estrogen to be reabsorbed.
- Iodine down-regulates estrogen receptors, making them less sensitive. It is particularly helpful for breast symptoms such as tenderness or breast cysts. Iodine is safe up to a dose of 500 mcg (0.5 mg), but higher dose iodine can damage the thyroid gland. Read my Iodine post.
- Natural progesterone. Progesterone counterbalances estrogen. It lightens periods and improves breast tenderness and premenstrual irritability. The progestins of hormonal birth control are not progesterone. Read The Crucial Difference Between Progestins and Progesterone.