• Allison Fahrenbach

The Gut Microbiome & The Estrobolome

The microbiome (the collection of microbes on and within your body) is incredibly powerful. It has far reaching impacts on your health, exerting it’s influence on everything from the absorption of nutrients, to your mood and energy, to your metabolism and immunity.

Emerging research is shedding light on specific microbes within your gut microbiome, which play a central role in the regulation of hormones within the body.

The health of the digestive system affects the reproductive system, and sex hormones can impact the gut.

Specifically, in this blog, I wanted to talk about the relationship between gut health and estrogen, and the specific group of microbes within your body known as the ESTROBOLOME

Estrogen is metabolized by a large group of bacterial genes collectively known as the estrobolome. Their main job is to ensure estrogen stays in balance. However when the estrobolome gets off balance it can activate too much estrogen (potentially leading to what’s called estrogen dominance) or cause estrogen levels to be too low.

Overall, some of the most common signs of imbalanced estrogen and other hormones include: bloating and digestive upset, acne, weight gain, low libido, heavy, light, or irregular periods, headaches, hot flashes, mood swings, anxiety, depression, PCOS, and cancers in the breasts, ovaries, or prostate.


When the gut microbiome is healthy, the estrobolome produces optimal levels of an enzyme called betaglucuronidase.

Beta-glucuronidase is synthesized by several types of gut bacteria, including Bacteroidetes and Firmicutes, and is an essential part of the body’s natural detoxification process.

However, just like with estrogen, balance is important.

When the gut is over loaded with bacteria increasing beta-glucuronidase activity, the overall estrogen burden on the body can increase.

As the liver metabolizes estrogen, this conjugated estrogen is delivered to the bile for excretion into the gut. Some of the estrogen will pass through the kidneys and be excreted in urine. The rest will pass through the GI tract where it will encounter the estrobolome.

A healthy estrobolome minimizes reabsorption of estrogen from the gut allowing safe removal as waste in stool, ensuring hormone balance.

But what happens if dysbiosis is present and the estroblome is unbalanced?


If there is dysbiosis present- such as an excess of bacteria that produce betaglucuronidase- the estrogen can revert back to its active form and be reabsorbed back into the bloodstream resulting in estrogen dominance.

Estrogen dominance can occur when either A) there is too much estrogen in the body or B) there is too little progesterone relative to estrogen. Symptoms of estrogen dominance (in women) include: increased fat in the hips, butt and stomach, fatigue, reduced sex drive, anxiety, bloating, insomnia, mood swings, brain fog, fibroids, irregular periods, sluggish metabolism, hair loss and even thyroid dysfunction.

Estrogen dominance has even been tied to autoimmune disorders like Hashimoto’s, arthritis, Grave’s disease, lupus, and others.

On the other hand, when there is decreased beta-glucuronidase activity, less estrogen is converted back to its active form, which can lead to excessively low levels of circulating estrogen.

This may occur when the gut lacks microbial diversity and therefore is lacking estrogen-metabolizing bacteria, too. One example of this is the link between low estrogen levels and cardiovascular disease, both of which are associated with decreased microbial diversity in the gut.

Symptoms of low estrogen can be hot flashes, mood swings, vaginal dryness, painful sex, irregular periods, headaches, depression, increased frequency of UTIS, and breast tenderness.

Unfortunately, gut dysbiosis and gut microbiome imbalance are very common and the delicate balance of the microbiome and estrobolome can be affected by many different factors which include genetics, age, weight, diet, alcohol, antibiotics, environmental pollutants and more.

In addition to variable levels of betaglucuronidase activity, intestinal microbial richness overall also influences the balance of estrogens circulating in the body.

The speed of motility can also affect how much estrogen is reabsorbed. If the transit time in the colon is slow due to constipation or too much stress the bacteria have more if an opportunity to reactivate estrogen. And if the gut is inflamed as in leaky gut, then the estrogen can leak back into the system

Gut dysbiosis can also promote the development of estrogen-related pathologies and chronic diseases.


Given the various roles that estrogen plays in the human body, it is not surprising that gut dysbiosis, which alters the estrobolome, has been associated with the development of several chronic diseases.

For example, estrobolome disruption in postmenopausal women is associated with an increased risk of obesity, cardiovascular disease, and loss of bone density such as osteoporosis.

Other research suggests that the estrobolome of both the gastrointestinal tract and vagina in women with endometriosis may have larger numbers of beta-glucuronidase–producing bacteria, leading to increased levels of circulating estrogens and inflammation that drive endometriosis.

Polycystic ovary syndrome (PCOS) is another condition that seems to be influenced by the balance of microbes in the estrobolome.

Studies suggest that imbalanced gut microbiota may promote increased androgen biosynthesis and decreased estrogen levels through lowered beta-glucuronidase activity, which contributes to hormonal imbalances characteristic of PCOS.

Emerging research also links dysbiosis of the estrobolome to various forms of cancer. This altered balance of gut microbes leads to increased levels of circulating active estrogens, which promote cell proliferation in estrogen-sensitive tissues such as the breasts, endometrium, cervix, and ovaries.


The balance and diversity of bacteria found in the estrobolome are affected by many of the same factors that affect the health of the gut microbiome, including age, diet, environmental exposures, and antibiotic use.

Just as you can adopt healthy habits to support the gut microbiome, there are several steps that you can take to support a healthy estrobolome

Increase dietary fiber: High-fiber diets, rich in a variety of plant-based foods, have been shown to lower beta-glucuronidase activity. In fact, one study found that women consuming a vegetable based higher fiber diet had triple the amount of estrogen in their feces than those eating a standard Western diet (lower in fiber).

High- fiber diets also speed up the flow of food and waste products through the digestive system, allowing less time for reabsorption of estrogen to take place.

Consider the role of phytoestrogens: Phytoestrogens, or natural plant compounds that mimic estrogen in the body, can have estrogenic or anti- estrogenic effects. It’s important to be aware of the role they play as they’re metabolized in the estrobolome, too.

They are found in many foods, including cruciferous vegetables, flaxseed, and soybeans. Some phytoestrogens bind weakly with estrogen receptor sites in the body. This prevents active estrogen from binding to these sites, which may be helpful in dealing with some estrogen-driven health issues. For example, there is a link between reduced breast cancer risk and consumption of phytoestrogens.

Hydrate: Not only does adequate hydration support a high-fiber diet, it can also promote bowel movements, allowing for proper elimination of estrogen (and other toxins) from the body. Remember, constipation is a contributing factor to estrogen imbalance. I recommend about a gallon of hydrating liquids a day for women and 1.5-2 gallons a day for men. This could be unsweetened teas (hot or iced) or fresh filtered water with lemon, lime or even cucumber for taste.

Consider crowding out sugar, dairy and gluten. Food is your best friend when it comes to healing your gut and your hormones, but that also means poor dietary choices can play a big role in compromising your health. Dairy, sugar, and gluten are major culprits in exacerbating bacterial imbalances. If you consume these foods frequently, it may be a good idea to consider ways in which you can reduce or remove them from your diet. Dairy, sugar, and gluten are “pro-inflammatory” foods and they contribute to dysbiosis in the gut. I have found most individuals experience better overall health when they minimize their consumption.

Eat foods rich in d-glucaric acid: The dietary compound d-glucaric acid is a precursor to a beta-glucuronidase inhibitor. Plant-based foods are good sources of d-glucaric acid. Rich sources include apples, apricots, bean sprouts, broccoli, cherries, grapefruit, oranges, and tomatoes.

Feed beneficial bacteria with probiotics and prebiotics: Foods full of prebiotics and probiotics are all important to support the health of your gut microbiome. This means they’ll boost the health of your estrobolome as well. Some strains of probiotics, including lactobacillus acidophilus, may reduce beta-glucuronidase activity, too.

If you tolerate prebiotic- and probiotic-rich foods, explore new ways you can add them to your diet. For instance, you might enjoy cooking with more garlic and onions (for prebiotics) or trying kefir (a probiotic source) as a replacement for milk on cereal. Adding a TBSP or two of sauerkraut or kimchi to meals is another easy way to add beneficial probiotics to your diet.

Lower exposure to synthetic xenoestrogens: Synthetic xenoestrogens, such as bisphenol A (BPA), are man-made estrogen-mimicking compounds. They are considered endocrine disruptors as repeated exposure can lead to endocrine- related health issues, such as altered immune and reproductive function.

Synthetic xenoestrogens have been found in many places, including food packaging, the environment (e.g., chemicals in wastewater), plastic water bottles (and the water in them), thermal paper receipts, and personal care products.

Try swapping plastic water bottles and plastic food containers for glass or stainless steel bottles and containers. Examine your body care products closely to assess if they contain xenoestrogens, such as parabens, that may have estrogenic activity.

Seek testing and support (as needed): If estrogen-related health issues are suspected or confirmed, consider discussing the health of your estrobolome with a healthcare provider, specifically a functional health coach or functional medicine specialist, or an endocrinologist.

There are also stool tests available to evaluate beta-glucuronidase activity in the gut as well as dietary supplements that may provide support for elevated beta-glucuronidase levels. For example, supplementation with calcium d-glucarate – a calcium salt of d-glucaric acid – can lower beta-glucuronidase activity and increase the body’s estrogen excretion.

Decrease alcohol intake: Regular alcohol intake has been associated with increases in serum estrogen levels. Regular drinking limits the livers ability to process toxins and waste, and excrete excess estrogen.

Drinking alcohol has also been linked to the development of small intestinal bacterial overgrowth (SIBO).

Consider swapping out an alcoholic beverage for a gut-friendly alternative like sparkling water with lime or bitters, or kombucha.

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