1. J Natl Cancer Inst. 2016 Apr 22;108(8):djw029. doi: 10.1093/jnci/djw029. The Intestinal Microbiome and Estrogen Receptor–Positive Female Breast Cancer Maryann Kwa et al. Abstract: The gut bacterial microbiome affects women’s circulating estrogen levels through a specific group of microbes called the estrobolome. The estrobolome modulates the enterohepatic circulation of estrogens, which affects both their excretion and circulation. Factors such as diet, alcohol intake, and antibiotics can modulate the estrobolome’s composition and functional activity. Research supports that interventions using prebiotics and probiotics could be designed to target gut bacterial species with $\beta$-glucuronidase activity to influence estrogen metabolism.
2. Review Mol Nutr Food Res. 2024 Mar;68(6):e2300688. doi: 10.1002/mnfr.202300688. From Gut to Hormones: Unraveling the Role of Gut Microbiota in (Phyto)Estrogen Modulation in Health and Disease
Nikki Kumari et al. Abstract: The human gut microbiota regulates estrogen metabolism through the "estrobolome," the collection of bacterial genes that encode enzymes like β-glucuronidases. These enzymes deconjugate and reactivate estrogen, mediating its enterohepatic circulation and bioavailability. Current evidence suggests that the gut microbiota is an integral regulator of estrogen status with clinical relevance to women's health and hormonal disorders.
3. Maturitas. 2017 Sep;103:45-53. doi: 10.1016/j.maturitas.2017.06.025. Estrogen-gut microbiome axis: Physiological and clinical implications James M Baker et al.
Abstract: One of the principal regulators of circulating estrogens is the gut microbiome. The gut microbiota regulates estrogens through secretion of β-glucuronidase, an enzyme that deconjugates estrogens into their active forms. Alterations in circulating estrogens may contribute to the development of conditions including obesity, metabolic syndrome, cancer, and polycystic ovarian syndrome (PCOS). Modulation of the microbiome composition subsequently impacts the metabolic profile and has been shown to alleviate many of the estrogen-modulated disease states.
4. mSystems. 2022 Apr 13;7(3):e00273-22. doi: 10.1128/msystems.00273-22. Menopause Is Associated with an Altered Gut Microbiome and Estrobolome, with Implications for Adverse Cardiometabolic Risk in the Hispanic Community Health Study/Study of Latinos Brandilyn A Peters et al. Abstract: Menopause is associated with a gut microbiome more similar to that of men, supporting that declining female sex hormones influence gut microbiome composition. The postmenopausal microbiome showed decreased abundance of microbial β-glucuronidase. Menopause-related gut microbiome changes were associated with an adverse cardiometabolic risk factor profile (e.g., lower HDL, higher blood pressure) in postmenopausal women.
5. Dermatol Ther (Heidelb). 2022 Jun 25;12(7):1535–1550. doi: 10.1007/s13555-022-00759-1. Estrogen Action and Gut Microbiome Metabolism in Dermal Health Edwin D Lephart, Frederick Naftolin et al. Abstract: The gut, based upon the microbial enzyme $\beta$-glucuronidase, which regulates estrogen’s enterohepatic recirculation, constitutes a gut-skin microbial axis. This axis revolves around systemically available estrogen to support immune function, counteract inflammation, and directly impact dermal health. Estrogen metabolism by gut bacteria affects not only cutaneous health, but also hormone-dependent disorders/cancers. Diet is paramount in maintaining the gut-skin axis, and supplementation with bioactive botanicals (phytoestrogens) may be employed to boost health and improve dermal parameters.