The Oestrobolome: The Gut Bacteria That Regulate Your Hormones
Dozens of gut bacterial species collectively form what researchers call the oestrobolome: the collection of microbial genes capable of metabolising oestrogens. These bacteria regulate circulating oestrogen levels through an enzyme called beta-glucuronidase, which determines whether oestrogen that has been processed by the liver is excreted or reabsorbed into circulation. A healthy, diverse oestrobolome maintains appropriate oestrogen regulation. A disrupted one does not.
A 2025 review published in Nutrients, examining diet, the gut microbiome, and oestrogen physiology in menopausal health, found that greater microbial diversity is positively associated with improved oestrogen regulation, while reduced diversity and altered bacterial ratios are linked to biomarkers of inflammation during perimenopause. The gut is not a passive participant in hormonal health. It is an active regulator of how hormones are processed and how much circulates in the body at any given time.
Hormonal balance is not just an ovarian function. It is a gut function too. The bacteria in your intestine determine how much oestrogen stays in circulation after your liver has processed it.
What Happens When the Oestrobolome Is Disrupted
When gut microbiome diversity declines, beta-glucuronidase activity becomes dysregulated. Oestrogen that should be excreted gets reabsorbed instead, creating oestrogen excess. Or beneficial bacteria that support oestrogen production decline, creating oestrogen deficiency. Both directions produce symptoms: worsened PMS, more intense perimenopause, irregular cycles, hormonal acne, mood instability, and difficulty managing weight.
A 2025 PMC review on gut microbiota and menopausal health found that during perimenopause, the relative abundance of beneficial bacteria such as Lactobacillus and Bifidobacteria is markedly reduced, while harmful bacteria increase. A 2024 study on gut microbiota and menopausal symptoms confirmed microbial and metabolic differences linked to hormonal change, including lower Bifidobacterium levels and fewer short-chain fatty acid-producing microbes. The microbiome shift and the hormonal shift happen together and influence each other.
Beyond Menopause: PMS, Cycles, and the Gut
The gut-hormone connection is not only relevant in perimenopause. It operates throughout the reproductive years. The gut microbiome regulates androgen metabolism as well as oestrogen, influencing testosterone levels and the hormonal environment that drives acne, libido, energy, and mood across the cycle. Women who experience severe PMS, significant mood changes in the luteal phase, or cycle-linked digestive disruption often show microbiome signatures consistent with hormonal dysregulation driven partly by the gut.
A 2024 study published in Gut Microbes confirmed that the gut microbiome responds to alteration in female sex hormone status and can exacerbate metabolic dysfunction. The relationship runs in both directions: hormones shape the microbiome, and the microbiome shapes hormonal availability. Managing one without addressing the other produces incomplete results.
Hormonal health is not purely a conversation between the ovaries and the brain. The gut bacteria sit in the middle of that conversation, translating and sometimes distorting the signals.
Supporting the Gut-Hormone Axis
The 2025 Nutrients review identified dietary fibre, synbiotics, and phytoestrogens as the most evidence-supported adjuncts to hormonal health via the gut microbiome. Prebiotic fibre is the most tractable of these. It consistently increases Bifidobacterium and Lactobacillus populations, the bacteria most associated with healthy oestrogen metabolism and reduced perimenopausal inflammation.
DULCI provides 7g of clinically studied prebiotic fibre per scoop, an excellent source of fibre by the regulated standard. It feeds the gut bacteria responsible for short-chain fatty acid production. It supports the gut environment the research consistently associates with hormonal balance across the reproductive lifespan.
PMS, perimenopause, hormonal acne, cycle-linked mood changes. These are not inevitable. They are partly determined by the gut bacteria that regulate how your hormones are processed and circulated.
The gut is in the hormonal conversation. It has always been. Most health plans just have not included it yet.
