Effects of Menopause on the Microbiome

Introduction:

A healthy balance between the host and its microbiome is vital. Hormonal changes after menopause can disrupt this balance, leading to health issues. Postmenopausal changes in the gut microbiome increase short-chain fatty acids and hydrogen sulfide. Lower estrogen levels raise vaginal pH, reducing Lactobacillus levels and affecting vaginal health. These changes contribute to the development of the genitourinary syndrome of menopause.

What Is Menopause?

Menopause happens when a woman has not had menstruation for 12 consecutive months. Preceding menopause is perimenopause, which typically begins between ages 45 and 55 and can last from about seven to 14 years. This phase involves significant hormonal shifts, including fluctuating levels of estrogen and progesterone hormones produced by the ovaries.

During perimenopause, women may experience changes in their menstrual cycles, hot flashes, weight gain, and changes in bone and heart health. The reduction in estrogen levels leads to these menopausal symptoms. Menopause is the end of a woman's reproductive years and is characterized by the permanent stopping of menstrual periods. Healthcare providers often use the term menopause to describe the whole phase of hormonal changes before and after the last menstrual period.

What Is the Role of the Urinary Microbiome?

The urinary microbiome is connected to various diseases, including overactive bladder, interstitial cystitis, bladder pain syndrome, bladder cancer, and urinary tract infections. This indicates its important role in urinary tract health.

Pathogens in the urinary microbiome often come from the gut and may also colonize the vagina. About 62.5 percent of urine species come from the intestines and 32 percent from the vagina, showing a close relationship between these microbiomes.

Hormonal changes during menopause can alter the gut and vaginal microbiomes, which in turn affect the urinary microbiome. Studying these changes is essential for understanding urinary tract diseases in postmenopausal women.

How Does Menopause Affect the Urinary and Gut Microbiome?

Menopause affects both the urinary and gut microbiomes in several ways. Changes in estrogen levels, which are influenced by the gut microbiome, can impact estrogen-related disorders. Studies suggest that postmenopausal women have lower vaginal Lactobacillus compared to premenopausal women, though their overall gut microbiome diversity does not show significant differences.

Hormone therapy can significantly alter the gut microbiome. Research confirms that women undergoing hormone therapy tend to have gut microbiomes similar to those of premenopausal women. Conversely, women not on hormone therapy exhibit different gut bacteria profiles, including higher levels of Proteobacteria and lower levels of Bacteroidetes.

Additional studies indicate that postmenopausal women show a higher Firmicutes and Bacteroidetes ratio with increased levels of Lachnospira and Roseburia compared to premenopausal women. Meta-analyses reveal that menopausal women have higher levels of Odoribacter and Bilophila, with decreased Sutterella, Roseburia, and Blautia levels. Increased Bilophila is linked to higher inflammation and potential gut damage. On the other hand, elevated Odoribacter levels lead to increased short-chain fatty acids, which may help reduce the risks of obesity and osteoporosis but can also contribute to inflammation.

How Does Menopause Affect the Vaginal Microbiome?

The vaginal microbiome is dynamic and influenced by factors such as age, ethnicity, physiological changes, and lifestyle. As women age, especially after menopause, the composition of the vaginal microbiota changes, impacting their overall quality of life. Typically, postmenopausal women experience a decline in Lactobacillus species, while other bacteria like Gardnerella vaginalis, Ureaplasma urealyticum, Candida albicans, and Prevotella species become more prevalent.

Studies have also found that menopausal women, especially those not using hormone replacement therapy, have lower percentages of Lactobacillus and vaginosis-associated bacteria compared to younger women. In addition, the prevalence of bacterial vaginosis is lower in menopausal women than in their younger counterparts. Rectal Lactobacilli may help maintain normal vaginal microbiota in menopausal women who lack vaginal Lactobacilli.

Hormone therapy has been shown to restore vaginal Lactobacillus levels to those seen in premenopausal women. Similarly, topical estrogen administration has been found to increase vaginal Lactobacillus. Probiotic treatments, such as those involving Lactobacillus strains, have also demonstrated potential for restoring normal vaginal flora and improving vaginal health.

How Does Menopause Affect the Urinary Microbiome?

Menopause can significantly alter the urinary microbiome, which may be linked to various urinary tract conditions such as urge urinary incontinence (UUI), overactive bladder (OAB), and recurrent urinary tract infections (UTI). After menopause, the diversity of the urinary microbiome increases, with a notable decrease in Lactobacillus and a rise in other bacteria like Gardnerella and Prevotella.

Studies show that postmenopausal women have different urinary microbiota compared to premenopausal women. Menopause is associated with a shift from Lactobacillus dominance to a more varied bacterial profile, which may contribute to an increased risk of urinary tract infections and other urinary issues.

Research on the impact of hormone therapy has yielded mixed results. While some studies found no significant changes in the urinary microbiome, others reported that local estrogen therapy can increase Lactobacillus levels and reduce the risk of urinary tract infections.

Overall, menopause affects the urinary microbiome in ways that could influence urinary health, but more research is needed to understand these changes and their implications for treatment.

How Does Genitourinary Syndrome of Menopause (GSM) Affect the Vaginal and Urinary Microbiomes?

Genitourinary Syndrome of Menopause (GSM) affects many postmenopausal women, with symptoms like vaginal dryness and urinary frequency. Research shows that the vaginal and urinary microbiomes are connected and can influence each other. For instance, Lactobacilli, which are more common in the vagina than in urine, are less prevalent in postmenopausal women, suggesting that changes in the vaginal microbiome could affect urinary health.

GSM symptoms are linked to hormonal changes, with about 50 percent of postmenopausal women experiencing these issues. Studies found that women with a Lactobacillus-dominant vaginal microbiome had fewer GSM symptoms and higher levels of certain hormones. The vaginal microbiome typically includes different types of Lactobacillus, and having a dominant Lactobacillus presence is associated with fewer symptoms.

Treatment options for GSM include estrogen therapy and Lactobacillus supplementation. Research indicates that using products with Lactobacillus can improve GSM symptoms and restore a healthy vaginal microbiome. Combining estrogen with Lactobacillus has also been effective in managing GSM.

Conclusion:

The gut, vaginal, and urinary microbiomes are interrelated, and imbalances in one can lead to various health issues. Menopause induces significant hormonal changes that affect these microbiomes, potentially leading to physical and health consequences. Understanding these microbiome changes in menopausal women is essential, with a particular focus on their link to diseases like endometrial cancer. Research on the postmenopausal urinary microbiome is limited but important, as changes here may contribute to common issues like urinary tract symptoms and recurrent cystitis.