The impact of the microbiota-gut-brain axis on endometriosis-associated symptoms: mechanisms and opportunities for personalised management strategies

Graphical abstract Abstract Endometriosis is a chronic inflammatory condition affecting one in ten women and those assigned female at birth, defined by the presence of endometrial-like tissue outside the uterus. It is commonly associated with pain, infertility, and mood disorders, and is often comorbid with other chronic pain conditions, such as irritable bowel syndrome. Recent research has identified a key role for the microbiota–gut–brain axis in health and a range of inflammatory and neurological disorders, prompting an exploration of its potential mechanistic role in endometriosis. Increased awareness of the impact of the gut microbiota within the patient community, combined with the often-detrimental side effects of current therapies, has motivated many to utilise self-management strategies, such as dietary modification and supplements, despite a lack of robust clinical evidence. Current research has characterised the gut microbiota in endometriosis patients and animal models. However, small cohorts and differing methodology have resulted in little consensus on the data. In this narrative review, we summarise research studies that have investigated the role of gut microbiota and their metabolic products in the development and progression of endometriosis lesions, before summarising insights from research into co-morbid conditions and discussing the reported impact of self-management strategies on symptoms of endometriosis. Finally, we suggest ways in which this promising field of research could be expanded to explore the role of specific bacteria, improve access to ‘microbial’ phenotyping, and develop personalised patient advice for reduction of symptoms such as chronic pain and bloating. Lay Summary Endometriosis is a chronic condition affecting one in ten women and those assigned female at birth, defined by the presence of tissue, similar to the womb lining, growing outside the womb. Symptoms include pelvic pain, period pain, pain during sex and when going to the toilet, digestive disturbance and bloating, infertility, depression, and anxiety. Standard treatments, including surgery and hormone-altering drugs, often have negative side effects. Many women with endometriosis use self-management strategies to control their symptoms, including changing their diet or taking supplements. Although some reports suggest such strategies are helpful, there is limited high-quality evidence to support their use. Here, we discuss how dietary adaptations could be impacting endometriosis-associated symptoms via changes to the bacteria within the gut. Gut bacteria communicate with the brain and influence inflammation throughout the body. Therefore, altering the gut bacteria through dietary changes can potentially benefit a variety of endometriosis-associated symptoms.