The Estrobolome What?

What is Estrobolome

The Estrobolome What?

Estrogen & The Gut Microbiome Connection

It might seem surprising that Dr. Kimberly Brown specializes in both gut and hormone complaints but they are very much related. The gut’s bacteria, the microbiome, affects estrogen levels and how that estrogen is used by your body. If the gut is not able to eliminate estrogen waste products detoxed by the liver, it’s sent back into the bloodstream where it can do harm to your health.

Estrogen waste products can cause weight gain, moodiness, increase insulin levels, diminish immune function, worsen PMS & PMDD, heighten perimenopausal & menopausal symptoms, and possibly even increase cancer risk. Healing the gut may help you lose weight, improve your immune system, lift your mood, lower your cancer risk, and balance your hormones!

It really is naturopathic medicine 101: meaning it all starts in the gut.

What exactly is the estrobolome?

Estrobolome is the bacteria in your gut that metabolize estrogens and produce something called beta glucuronidase. Beta glucuronidase is a stool marker for the excretion of estrogens. It increases when the gut and microbiome is unhealthy, causing estrogens to be reabsorbed. Your gut’s health is influenced by your age, diet, alcohol, stress, and antibiotic use. As people age, they have a less diverse microbiome which then affects how their gut metabolizes estrogens. Poor gut health can worsen PMS, PMDD, perimenopausal & menopausal symptoms, and even andropause symptoms (men produce more estrogens as they age).

The liver and gut are essential parts of the detox system for estrogens. From the bloodstream, estrogens go to the liver and then the intestines to be excreted. But if the estrogens are not excreted, they are reabsorbed into the bloodstream. This is why birth control and hormone replacement therapy can be given orally. We want them to be absorbed into the bloodstream but the estrogens from the liver are estrogen waste products. We don’t want them to be reabsorbed!

The estrogen given in bioidentical hormone replacement is estradiol and estriol. Estriol is an end product and cannot convert to anything, but estradiol can convert to estriol, estrone, and other metabolites. Other than estriol, which is a beneficial estrogen, it’s essential to rid the body of estrone and other metabolites. The liver metabolizes these estrogen waste products into the bile as conjugated estrogens and sends them to the intestines.  The microbiome then packages them for excretion.

But what happens if your gut is underpopulated, overpopulated, or sick with pathogenic bacteria?

What happens to those estrogen waste products? They are reabsorbed back into the bloodstream. Not only does sending them back to the liver make your liver work harder, reabsorption of estrogens prolongs your exposure to estrogens causing estrogen dominance, worsening PMS and PMDD, and increasing the risk of estrogen driven neoplasms.

Optimizing the gut, liver, and hormone balance help my patients feel better and may even prolong their lives.

This is why I work with the gut. I’ve seen too many women with IBS (Irritable Bowel Syndrome) who also suffer with hormone imbalances. In fact, Small Intestinal Bacterial Overgrowth (SIBO) which is often the underlying cause of IBS, often is accompanied by hormone complaints such as anxiety, insomnia, PMS, and severe perimenopausal & menopausal symptoms. SIBO wrecks havoc on hormones! The overgrowth in the small intestines causes dysbiosis, an imbalance of gut bacteria, in the entire gut which compromises metabolization of estrogens. Estrogen dominance and hormone imbalance ensues.

Heal Your Gut. Heal Your Hormones.

Diet, Nutriceuticals, Botanicals

Deconjugation of estrogens can be improved with nutriceuticals and botanicals. But first, the health of the gut needs to be quantified with stool testing. Comprehensive digestive stool analysis details what microbes are in the gut from pathogenic to healthy, undergrowth to overgrowth, digestive health, immune status, and levels of beta glucuronidase.

Beta Glucuronidase

Remember that beta glucuronidase can cause the reabsorption of estrogen waste products. If beta glucuronidase is high, plant based diets are best. Diets high in meat increase beta-glucuronidase. Vegans excrete 2 to 3 times more estrogens in their feces than omnivores! Omnivores have about 50% more unconjugated estrogens than vegans. You do not need to be vegan, but eating more fresh vegetables is recommended.

Fill that plate with lots of vegetables!

There are foods that lower Beta Glucuronidase like fermented or cultured dairy products, cruciferous vegetables, and black currant extract.

Calcium D-glucarate has also been shown to inhibit beta-glucuronidase.


In general, most people can take a probiotic containing lactobacillus and bifidobacteria, but take caution with probiotics. Probiotics can cause SIBO, Small Intestinal Bacterial Overgrowth, to worsen. This is why I recommend comprehensive digestive stool analysis first.


Vitamin A is supportive to the intestinal immune system which has profound effects on the microbiome.

Vitamin D has been shown to reduce opportunistic pathogens in the gut and increase biodiversity in the microbiome. A study found that a level of 55 was adequate to see improvements in microbiome health.

Omega-3s increase butyrate producing bacteria in the gut. Butyrate is a short chain fatty acid that supports intestinal health and reduces inflammation.

Fiber & Resistant Starch

Disclaimer: Fiber and resistant starch can worsen IBS due to SIBO and ulcerative colitis. It will cause bloating and discomfort. Again, this is why I recommend comprehensive digestive stool analysis.

RDA for fiber is 25-30 grams per day but Americans average only 15 grams per day. The modern diet is deficient in good fiber sources like whole grains, nuts, and seeds. Most fruits and vegetables have only a little fiber. The best fiber is both soluble and insoluble. Insoluble fiber like bran will bind to estrogens in the gut. Other insoluble fibers are flax and chia seeds, especially useful if soaked first to create a gel. In addition to binding estrogens, flax and chia seeds give us short chain fatty acids like buyrate (microbiome food).

Resistant starch: This is plant based and gets fermented. Uncooked potatoes, a favorite of my mother’s, is a great source of resistant starch. But if you, like myself, don’t care for uncooked potatoes, no fear. You can simply reheat cooked potatoes. A potato that has been cooled and then reheated contains high amounts of resistant starch! Other foods high in resistant starch are jerusalem artichokes, whole grains, cabbage, beans, apples, onions, garlic, and green bananas. All these foods except green bananas are high in FODMAPs so are a no go for SIBO and can be problematic for ulcerative colitis.

Perhaps you’ve heard of prebiotics. Prebiotics are a type of fiber like inulin, psyllium, and acacia that gut bacteria thrive on. Essentially, they are food for the gut. Again, these are foods that must be avoided in SIBO and ulcerative colitis.


Polyphenols, important phytochemicals, act like phytoestrogens. Structurally they are similar to estrogen. They mimic the action of estrogen. But if the gut is unhealthy, it cannot metabolize these polyphenols into estrogen like compounds. The most important phytoestrogens are soy, flax, berries, seeds, and nuts. Phytoestrogens have anti-inflammatory and antioxidant properties. Unfortunately, the American diet is low in phytoestrogens. The Western diet contains less than 1 mg per day compared to the Asian diet which contains 25-100 mg per day. Asians experience less cases of osteoporosis, breast cancer, and menopausal symptoms.

Am I saying estrogen might prevent breast cancer? I am not. But it is true that it is not a foregone conclusion that estrogen causes breast cancer. There could be something else in these phytoestrogens like antioxidant and anti-inflammatory compounds which are breast protective.

Hormone Balance

One of the reasons why a lot of herbal and hormone treatments for estrogen dominance, PMS, and menopause fail is because the gut is never addressed. Without a healthy gut, your body cannot metabolize the herbs into useful chemical constituents. Without a healthy gut, your body cannot excrete the estrogen waste products produced from oral birth control or hormone replacement therapy. If a patient does not respond well to herbal or hormone treatments, I examine how they are detoxifying in the liver and in the gut.

Want to Work With Me?

Schedule your free phone consultation HERE.

Dr. Kimberly Brown, ND, LAc
Naturopathic Doctor
(408) 357-3422
San Jose Integrative Medicine
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