The Changing Gut Flora after Menopause: How Women’s Microbiome Becomes Similar to Men’s and What it Means for Women’s Health.
Menopause, characterised by the cessation of women’s menstruation and with it a marked decrease in sex hormones, particularly oestrogen and progesterone. While hot flashes, mood swings and changes in bone density often dominate discussions about menopause, new research highlights another, less visible but fundamental change: the transformation of the gut microbiome. Studies suggest that after menopause, women’s gut flora begins to resemble men’s, a change driven by hormonal fluctuations that can have far-reaching effects on women’s health, something that has also completely escaped the attention of health professionals.
The gut microbiome and sexual dimorphism
The gut microbiome – the trillions of microorganisms living in the gastrointestinal tract – plays a crucial role in human health, influencing digestion, immunity, metabolism and even mental health. Scientists have long observed sexual dimorphism in the gut microbiome, meaning that men and women have distinctly different microbial communities inside them. These differences are partly attributed to sex hormones. Oestrogen promotes the growth of specific bacteria, contributing to a greater microbial diversity in premenopausal women compared to men. This diversity is often linked to better general health because a more diverse microbiome can more effectively fight pathogens and regulate body functions.
Research published in 2022 in the International Journal of Women’s Health underlines this sexual dimorphism, noting that pre-menopausal women exhibit a more diverse gut microbiome than men, with higher abundance of bacteria such as Bifidobacterium and Lactobacillus, which are associated with oestrogen metabolism. However, after menopause, this diversity decreases, and the microbial composition changes and becomes more similar to that seen in men; thus, the loss of oestrogen and progesterone fundamentally alters the ecological system of the gut.
Menopause and the Gut: What the Research Shows
A 2022 study in mSystems analysed nearly 2,000 individuals, including premenopausal women, postmenopausal women and men, mainly from Latin American populations. The researchers found that postmenopausal women had significantly lower microbial diversity than their premenopausal counterparts. Instead, their gut flora showed increased levels of bacteria such as Sutterella wadsworthensis, which is linked to higher blood pressure, and decreased levels of oestrogen-metabolising bacteria. Women thus lose the protective microbial properties that female sex hormones cause.
Another study, presented by ZOE at the Nutrition Society Winter Conference in January 2025, confirms these findings. It highlights that the decrease in oestrogen during menopause correlates with a decrease in gut bacterial diversity and a shift towards microbial profiles typical of men. The study also notes that these changes can exacerbate menopausal symptoms such as hot flushes and increase the risk of conditions such as osteoporosis and heart disease. .
Studies in animals also support these findings. Research on ovariectomised mice – which mimic the hormonal decline of menopause – shows reduced microbial diversity, increased gut permeability and a higher prevalence of bacteria associated with metabolic diseases. There is a causal link between oestrogen loss and microbiome changes. Although the sample sizes in some studies are small, the consistency of these observations across populations points to a robust link between menopause, hormones and gut microbiota.
The Estrobolome: A Key Player
An important concept in this research is the estrobolome, the subset of gut bacteria that can metabolise oestrogen. These microbes produce enzymes such as β-glucuronidase, which ‘recycle’ oestrogen back into the circulation and maintain hormonal balance. Premenopausal women usually have a robust estrobolome that supports higher estrogen levels and microbial diversity. However, when oestrogen production drops after menopause, the estrobolome weakens, leading to a feedback loop: fewer oestrogen-metabolising bacteria result in lower oestrogen availability, further altering the bacterial flora.
A 2023 study in Gut Microbes examined this dynamic and found that postmenopausal women have reduced estrobolome activity, which may contribute to metabolic dysfunction. The researchers noted that this weakened estrobolome is associated with increased inflammation, a known driver of chronic diseases. This interplay between hormones and gut bacteria highlights why the microbiome change during menopause is not just a curiosity but a very big potential health problem.
Health problems
The convergence of women’s gut flora with men’s after menopause has significant health implications, particularly in three areas: cardiometabolic health, bone density and mental health.
Oestrogen is cardioprotective, and its decrease after menopause increases the risk of heart disease and metabolic syndrome. The gut microbiome change amplifies this risk. Menopause-related microbiome changes are directly linked to higher blood pressure, increased waist circumference and lower HDL cholesterol. These changes mirror the cardiometabolic profile of men, who are at higher risk of heart disease at younger ages. A concern here is that older women’s heart problems often go undetected by health services because women are not expected to be at risk.
The loss of microbial diversity can also impair glucose metabolism and increase the risk of type 2 diabetes. A 2023 study in Menopause found that disruption of the gut microbiome during menopause correlates with weight gain, insulin resistance and higher cholesterol levels.
Osteoporosis, the loss of bone density, is a major concern for postmenopausal women, as oestrogen supports bone formation. Research in mice suggests that microbiome changes, particularly increased gut permeability, contribute to bone loss by allowing inflammatory molecules to enter the circulation. A 2025 review article in npj Women’s Health noted that postmenopausal women have lower levels of Ruminococcus, a bacterium that produces short-chain fatty acids beneficial to bone health, further linking microbiome changes to skeletal health.
The gut-brain axis links the microbiome to mood and cognition. Menopause-related dysbiosis – imbalances in gut bacteria – can exacerbate anxiety, depression and cognitive decline. A 2022 study in BMC Women’s Health found that women with menopausal syndrome had lower prevalence of mood-supporting bacteria such as Bifidobacterium animalis, suggesting that microbiome changes may exacerbate psychological symptoms. A diversified gut flora may more effectively suppress pathogens, potentially stabilising mood by reducing inflammation.
Menopause-related gut changes can affect the vaginal and urinary microbiome and increase susceptibility to infections. Gut dysbiosis can disrupt the balance of Lactobacillus species in the vagina, contributing to conditions such as recurrent cystitis and vaginal dryness.
Potential interventions
Given the modifiable nature of the gut microbiome, there are ways to mitigate these changes. Perhaps most important is diet, as high-fibre foods, fermented products, and a diet high in protein and plant-based foods promote microbial diversity. The need for protein and vegetables is significantly much higher for older women than previously thought. The need for vitamin D, K2, zinc, boron and magnesium is also high.
Probiotics and prebiotics also show promising results. Studies suggest that strains such as Lactobacillus and Bifidobacterium can restore microbial balance and support the estrobolome. A 2021 study in Frontiers in Cellular and Infection Microbiology found that probiotic supplementation in ovariectomised rats improved gut diversity and cognitive functions, suggesting similar potential in humans. Products such as sauerkraut and kimchi have far more and more diverse bacterial strains than most supplements and also provide nutrition to the bacteria.
Research indicates that hormontreatments, HRT can partially restore microbial diversity, although the effects vary. However, HRT is not suitable for all women, making microbiome-targeted interventions such as diet and probiotics more appealing. Lifestyle factors such as exercise, stress management and adequate sleep also support gut health. An often overlooked factor is also how extremely important physical exercise in younger years is to build up sufficient bone mass for old age.
https://www.everydayhealth.com/digestive-health/can-menopause-change-your-gut-microbiome
Gut microbial beta-glucuronidase: a vital regulator in female estrogen metabolism
Estrogen-gut microbiome axis: Physiological and clinical implications
Menopausal shift on women’s health and microbial niches
