What Are Postbiotics?
What Are Postbiotics? A Comprehensive Guide to the New Frontier in Gut Health In the world of gut health, most ...
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The intricate relationship between the gut microbiome, estrogen, and estrogen-dependent conditions such as endometriosis and premenstrual syndrome (PMS) has garnered growing attention in recent years. At the heart of this connection lies a specific subset of gut bacteria known as the estrobolome, which plays a pivotal role in estrogen metabolism and overall hormonal balance. (source)
This blog delves into how the gut influences estrogen levels, its implications for health, and the potential benefits of targeted interventions like probiotics and prebiotics.
The estrobolome refers to the collection of gut bacteria, and their genes, capable of metabolising estrogens. These bacteria produce enzymes, particularly one called beta-glucuronidase, that regulate the reactivation and recirculation of estrogens within the body.
Let’s briefly summarise how this all works.
Estrogen can be produced from the ovaries, adrenal glands, and adipose tissue (body fat). It is metabolised in the liver and then excreted into the bile which ends up in the intestine. Here, the estrobolome can influence the reabsorption back into the bloodstream or facilitate its excretion via faeces.
When this process is impaired through an imbalance in the gut microbiome it may result in a reduction, or increase, of circulating estrogens. The alteration in circulating estrogens may contribute to the development of conditions including obesity, metabolic syndrome, cancers including breast, endometrial, and ovarian cancers, endometrial hyperplasia, endometriosis, polycystic ovary syndrome, fertility, cardiovascular disease (CVD) and cognitive function (source, source).
Several bacterial genera in the gut microbiome, including Bacteroides, Bifidobacterium, Escherichia coli, and Lactobacillus, can produce beta-glucuronidase (source). These are all tested for in our Ultimate Gut Health Test.
It’s important to appreciate that this is a bi-directional relationship too, estrogen levels also influence the composition as well as the diversity of the gut microbiome (source).
The gut microbiome may influence estrogen dependent conditions via 3 different mechanisms:
I am going to focus on endometriosis, PMS, and PCOS in this blog but this paper does an amazing job of summarising the research demonstrating the strong link between the gut microbiome and estrogen. Here are some fascinating examples:
Again all these bacteria are tested for in our Ultimate Gut Health Test.
Endometriosis is a chronic condition characterised by the growth of endometrial-like tissue outside the uterus, often driven by elevated estrogen levels.
Emerging research suggests that dysbiosis – an imbalance in the gut microbiome – may exacerbate estrogen dominance by altering the activity of the estrobolome. Increased beta-glucuronidase activity in dysbiotic guts can lead to excessive estrogen reabsorption, fuelling endometriosis progression. Interestingly, research has shown a significant increase in the bacteria ‘Escherichia coli’ in the faeces of endometriosis patients as well as a depletion of protective bacteria (source). Remember this bacteria is known to produce the beta-glucuronidase enzyme.
Also, a recent pilot study suggested that leaky gut is a frequent finding in patients with endometriosis (source).
Studies have shown that gut health interventions, including dietary modifications and targeted probiotics, may help modulate the microbiome to restore balance. For example, studies have found that Lactobacillus and Bifidobacterium can reduce the proportion of β-glucuronidase-producing bacteria in the intestine, leading to a decrease in estrogen reabsorption rate (source).
As a result of all of this, researchers are starting to discuss how the potential use of microbiome testing, as a non-invasive method for detecting endometriosis, is promising. The average delay in diagnosing endometriosis, due to the nonspecific nature of its symptoms, is significant, ranging from 4 to 12 years, and diagnosis is an invasive procedure. This makes a simple microbiome test an appealing proposition to complement existing diagnostic procedures (source).
PMS encompasses a range of emotional, physical, and behavioural symptoms tied to the menstrual cycle. Hormonal fluctuations, particularly in estrogen and progesterone, play a significant role in triggering these symptoms. The gut microbiome’s ability to modulate estrogen levels suggests it could influence PMS severity.
Research indicates that a healthy microbiome may help buffer hormonal fluctuations by promoting optimal estrogen metabolism. Conversely, a disrupted microbiome might worsen symptoms by increasing systemic inflammation and contributing to hormonal imbalances (source, source).
Studies have demonstrated that gut specific interventions can alleviate some of the symptoms associated with PMS including depression (source). While not researched specifically in PMS, certain probiotic strains may help to alleviate the bloating and digestive discomfort associated with PMS, such as Lactobacillus acidophilus NCFM which can be found in Everyday Extra.
PCOS is a hyper-androgen and low estrogen driven disease, and patients suffering from PCOS have significantly lower gut microbiome diversity compared to healthy controls. These variations in gut microbiome compositions highlight the interaction between microbiome composition, sex hormone levels and PCOS. In fact a meta-analysis published in 2023 concluded that there is a causal relationship between the gut microbiome and PCOS (source).
Leaky gut (source) and oxidative stress (source) are also associated with PCOS.
Fascinatingly, evidence of an increase in testosterone levels due to the gut microbiome alludes to the existence of the “testrobolome”. Similar to the estrobolome, the testrobolome may influence sex hormone driven disease states (source).
Testosterone has been shown to be produced in the gut by the bacteria ‘Clostridium scindens’ (source).
It should therefore come as no surprise that we have evidence demonstrating the efficacy of gut-specific interventions, such as probiotics, in PCOS (source).
We have known for decades that a high-fiber diet reduces estrogen concentrations in premenopausal women, presumably because it reduces beta-glucuronidase activity (source).
An excellent review was published in 2023 (source) on diet and endometriosis which discussed how reducing dietary fat and increasing dietary fiber have been shown to reduce circulating estrogen concentrations, suggesting a potential benefit for individuals with endometriosis, as it is an estrogen-dependent disease. Meat consumption is associated with greater risk of developing endometriosis. Anti-inflammatory properties of plant-based diets may benefit women with endometriosis. Furthermore, consumption of vitamin D has been shown to reduce endometrial pain via increased antioxidant capacity and supplementation with vitamins C and E significantly reduced endometriosis symptoms, compared with placebo.
Probiotic supplements containing strains from Lactobacillus and Bifidobacterium have shown promise in enhancing estrogen metabolism and reducing inflammation. These strains may help lower β-glucuronidase activity and promote the excretion of excess estrogens, creating a more favourable hormonal environment (source).
Bifidobacterium breve has been shown to have this property. It can be found in Bifidobacterium by G&G.
But research has also demonstrated that we can use probiotics with the opposite purpose – to increase estrogen (when this is appropriate). In a randomised, double-blind, placebo-controlled trial, researchers demonstrated that estrogen levels in healthy peri- and postmenopausal women given a probiotic formula containing Lactobacillus brevis KABP052 were maintained over time, whereas levels significantly decreased in the group given a placebo (source). Unfortunately this strain of probiotic is not yet commercially available.
While promising, this field is still evolving, and more clinical trials are needed to establish definitive guidelines for using probiotics in managing estrogen-related conditions.
The best advice I can give is to consider working with an experienced nutritional therapist and to select the probiotic based on your specific symptoms and from gut health test results (stay tuned for an upcoming blog on how to select the right probiotic!).
Prebiotics, the fibers that feed beneficial gut bacteria, are crucial for fostering a balanced microbiome. Foods rich in prebiotics, such as garlic, onions, bananas, and whole grains, can enhance the growth of estrobolome-supporting bacteria. Supplementing with prebiotics can also improve gut health and support estrogen balance over time (source). One study showed that inulin lowered beta-glucuronidase ativity (source).
Recommended Product: Inulin.
Butyrate, a metabolite of various bacteria in the gut, can support a healthy microbiome and help heal leaky gut, amongst other things and can often be considered within a gut healing protocol. Research has found that it may help patients with endometriosis (source). You can read our recent blog on butyrate here.
Recommended Product: Tributyrin.
Regular exercise, stress management, and minimising exposure to endocrine-disrupting chemicals are additional steps to maintain hormonal balance and support transition through the menopause (source, source).
Some polyphenols, like those found in black tea and green tea, can inhibit beta-glucuronidase activity.
Resveratrol and curcumin, are believed to modulate a variety of signalling pathways and have therapeutic effects in endometriosis and PCOS (source, source).
A very popular product for overall estrobolome support is Bio.Clear Estro. This is a botanical and nutrient blend developed to support healthy oestrogen metabolism by encouraging the production of the enzymes involved in the oestrogen detoxification process, and by supporting a healthy oestrobolome.
The gut microbiome’s influence on estrogen metabolism and estrogen-dependent conditions highlights the importance of gut health in hormonal balance. The estrobolome plays a central role in regulating estrogen levels, with profound implications for conditions like endometriosis, PCOS and PMS. By supporting the gut through targeted probiotics, prebiotics, and lifestyle changes, individuals can take proactive steps toward better hormonal health. As research continues to unfold, the potential for microbiome-based therapies offers hope for those managing these challenging conditions.