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There is a group of gut bacteria whose sole job is managing your oestrogen levels
Most people think of oestrogen as something produced by the ovaries and regulated by the brain. That is partly true. But there is a critical step in the process that happens in the gut, and it depends entirely on your gut bacteria.
The estrobolome is the term for the specific collection of gut microbes capable of metabolising oestrogens. These bacteria produce an enzyme called beta-glucuronidase that determines how much oestrogen is reabsorbed into your bloodstream and how much is excreted. When the estrobolome is healthy and diverse, this process runs smoothly. When it is disrupted, oestrogen levels can swing in either direction, with consequences for bone health, mood, body composition, and long-term disease risk.
The term was first defined in a landmark paper in Cell Host & Microbe (Plottel and Blaser, 2011), and since then, research into the gut-hormone connection has expanded rapidly.
How the Estrobolome Works
To understand the oestrobolome, you need to understand what happens to oestrogen after it has done its job in the body.
Once oestrogen has been used, the liver processes it for elimination through a step called conjugation. This essentially deactivates oestrogen and tags it for excretion into the gut via bile. Under normal circumstances, most of this conjugated oestrogen would leave the body in stool.
But certain gut bacteria produce beta-glucuronidase, an enzyme that reverses this conjugation. It reactivates the oestrogen, allowing it to be reabsorbed through the intestinal wall and recirculated in the bloodstream. A study in the Journal of Biological Chemistry (Ervin et al., 2019) confirmed that gut microbial beta-glucuronidases reactivate oestrogens as potent oestrogen receptor agonists, meaning they become fully biologically active again.
This is not a flaw in the system. It is how the body fine-tunes oestrogen levels. The estrobolome acts as a secondary regulator, and its composition determines the balance between oestrogen excretion and recirculation.
What Happens When the Estrobolome Is Disrupted
When gut microbiome diversity is healthy, the estrobolome produces appropriate levels of beta-glucuronidase, and oestrogen homeostasis is maintained. Problems arise when this balance shifts.
Too much beta-glucuronidase activity
An overgrowth of beta-glucuronidase-producing bacteria leads to excessive oestrogen reabsorption. This creates a state of relative oestrogen excess, which is associated with increased risk of oestrogen-dependent conditions including breast cancer, endometriosis, and fibroids. A study by Flores et al. (2012) in the Journal of Translational Medicine found that higher gut microbial diversity correlated with healthier oestrogen metabolism in postmenopausal women, while lower diversity was associated with less favourable oestrogen metabolite profiles.
Too little beta-glucuronidase activity
Conversely, when beneficial gut bacteria are depleted (through antibiotics, poor diet, or age-related decline), beta-glucuronidase activity drops and more oestrogen is excreted than intended. This accelerates oestrogen decline beyond what the ovaries alone would cause, contributing to more severe menopausal symptoms, faster bone density loss, and increased cardiovascular risk.
The Estrobolome During Perimenopause and Menopause
This is where the estrobolome becomes particularly relevant. During perimenopause and menopause, ovarian oestrogen production declines significantly. At the same time, the gut microbiome itself is undergoing age-related changes: diversity drops, beneficial species decline, and the overall microbial environment shifts.
A comprehensive review in Maturitas (Baker et al., 2017) described this as a compounding problem. The ovaries produce less oestrogen while the gut simultaneously becomes less effective at recycling what remains. The result is a steeper and more symptomatic oestrogen decline than would occur from ovarian changes alone.
This dual decline helps explain why some women experience significantly worse menopausal symptoms than others, even with similar hormonal profiles. The state of their gut microbiome, and specifically their estrobolome, may be a differentiating factor.
For more on how gut diversity changes with age, see our guide to gut health after 40.
What the Estrobolome Affects Beyond Menopause Symptoms
Bone density
Oestrogen is a primary regulator of bone remodelling. When oestrogen levels fall, bone breakdown accelerates and osteoporosis risk increases sharply. If the estrobolome is not functioning well, oestrogen decline is steeper, and bone loss may progress faster. Supporting gut health during and after menopause is therefore relevant to skeletal health, not just digestive comfort. See our post on why bone health matters for more on this.
Cardiovascular health
Oestrogen has a protective effect on blood vessels and cholesterol profiles. The rapid cardiovascular risk increase that women experience after menopause is partly driven by oestrogen decline. A poorly functioning estrobolome that accelerates this decline may contribute to earlier and more pronounced cardiovascular changes.
Mood and cognition
Oestrogen influences serotonin, dopamine, and other neurotransmitters. The mood changes, brain fog, and anxiety that many women report during perimenopause are partly mediated by falling oestrogen. If gut dysbiosis is compounding this decline through poor estrobolome function, supporting the microbiome becomes part of supporting mental health during the transition. For more on the gut-brain connection, see our post on the gut-brain axis and mood.
Weight and metabolism
Oestrogen helps regulate fat distribution and insulin sensitivity. As levels fall, many women notice increased abdominal fat and changes in how their body handles glucose. A disrupted estrobolome that accelerates oestrogen loss may worsen these metabolic shifts.
What You Can Do to Support Your Estrobolome
The practical steps for supporting the estrobolome overlap significantly with general gut health recommendations, but with some specific emphasis points.
Eat a diverse, fibre-rich diet
Microbiome diversity is the foundation of a healthy estrobolome. The more varied your plant intake, the wider the range of bacterial species you support. The 30 plants per week target from the American Gut Project is a useful benchmark. Cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, kale) deserve particular emphasis: they contain compounds like indole-3-carbinol that support healthy oestrogen metabolism independently of the microbiome. For a detailed dietary framework, see our guide to the microbiome diet.
Include fermented foods regularly
A trial published in Cell (Wastyk et al., 2021) found that a high-fermented food diet increased microbiome diversity and reduced inflammatory markers over 10 weeks. Greater diversity supports a healthier estrobolome. Live yoghurt, kefir, sauerkraut, kimchi, and miso are all effective sources. See our detailed post on fermented foods and gut health.
Prioritise prebiotic fibres
Garlic, leeks, onions, asparagus, oats, and Jerusalem artichokes feed the beneficial Bifidobacterium and Lactobacillus species that support balanced beta-glucuronidase activity. These are the species most likely to decline with age and during the menopausal transition.
Consider targeted probiotic support
Multi-strain probiotics that include Lactobacillus species may be particularly relevant for oestrobolome support, as these bacteria are directly affected by oestrogen decline and are among the first to diminish during perimenopause.
Our Biome Bliss contains five clinically researched strains, including Lactobacillus species, in a fermented liquid format using organic honey, apple juice, and 25 organic herbs. The fermentation produces beneficial postbiotic compounds alongside the live bacteria, and the formula contains no artificial fillers or binders.
Limit unnecessary antibiotics and gut disruptors
Antibiotics are the most significant single disruptor of the estrobolome. Each course reduces microbial diversity, and recovery becomes less complete with age. Where antibiotics are medically necessary, supporting the gut during and after the course (through diet and probiotic supplementation) is worth discussing with your GP. Alcohol, chronic stress, and ultra-processed foods also reduce microbiome diversity over time.
Consider complementary nutrient support
Vitamin D and magnesium both play roles in bone health and hormonal balance during menopause. For more details, see our posts on vitamin D during menopause and magnesium during menopause.
What to Expect
Microbiome diversity can begin to shift within days of dietary changes, though meaningful, sustained improvement in estrobolome function likely takes four to eight weeks of consistent effort. The effects on oestrogen metabolism are harder to measure directly without specialist testing, but improvements in digestive comfort, energy levels, and symptom severity during perimenopause are commonly reported within this timeframe.
For a broader overview of how the gut microbiome works, see our guide to what the gut microbiome is and why it matters.
FAQ
What is the estrobolome in simple terms?
The estrobolome is the collection of gut bacteria that can metabolise oestrogen. These bacteria produce an enzyme called beta-glucuronidase that determines how much oestrogen your body reabsorbs and how much it excretes. When the estrobolome is balanced, oestrogen levels are better regulated. When it is disrupted, oestrogen can swing too high or too low.
Can gut health affect menopause symptoms?
Yes. The gut microbiome helps regulate how much oestrogen is recycled back into your bloodstream. During menopause, when ovarian oestrogen production drops, a healthy estrobolome can help your body retain more of its remaining oestrogen. A disrupted gut may accelerate oestrogen decline, potentially worsening symptoms like hot flushes, mood changes, and sleep disruption.
Does taking probiotics help with oestrogen balance?
Research is still developing, but there is evidence that Lactobacillus species in particular are affected by oestrogen decline, and that supporting microbiome diversity through probiotics and fermented foods improves overall oestrogen metabolism. Probiotics are not a replacement for medical treatment, but they may support hormonal balance as part of a broader dietary approach.
Can antibiotics disrupt the estrobolome?
Yes. Antibiotics are the most significant known disruptors of the estrobolome because they broadly reduce gut microbial diversity, including the specific bacteria that produce beta-glucuronidase. This is one reason why some women notice hormonal symptoms or menstrual changes after a course of antibiotics. Recovery becomes less complete with age, making gut support during and after antibiotic courses increasingly important.
Is the estrobolome relevant for men?
Men have oestrogen too, in smaller amounts, and it plays roles in bone health, cardiovascular function, and brain health. The estrobolome influences oestrogen metabolism in both sexes. However, the most significant clinical relevance is currently in women, particularly during perimenopause and menopause, where the interaction between declining ovarian oestrogen and gut health has the most pronounced effects.
References
- Plottel CS, Blaser MJ. Microbiome and malignancy. Cell Host & Microbe. 2011;10(4):324–335. PubMed
- Ervin SM et al. Gut microbial beta-glucuronidases reactivate estrogens as potent estrogen receptor agonists. Journal of Biological Chemistry. 2019;294(49):18586–18599. PubMed
- Baker JM et al. Estrogen-gut microbiome axis: Physiological and clinical implications. Maturitas. 2017;103:45–53. PubMed
- Flores R et al. Fecal microbial determinants of fecal and systemic estrogens and estrogen metabolites: a cross-sectional study. Journal of Translational Medicine. 2012;10:253. PubMed
- Wastyk HC et al. Gut-microbiota-targeted diets modulate human immune status. Cell. 2021;184(16):4137–4153. PubMed
This article is for informational purposes only and does not constitute medical advice. If you are experiencing menopausal symptoms or considering supplementation, speak to your GP or a registered dietitian before making changes.
