Many women experience psychological symptoms related to the female cycle — especially premenstrually — and during menopause, such as mood swings, irritability, inner restlessness, depressive moods, or sleep disturbances.

For a long time, these symptoms were viewed primarily as a direct consequence of hormonal changes. While hormones still play a central role, current research paints a far more complex picture: hormonal processes closely interact with stress, the nervous system, and the gut.

In particular, the microbiome and its influence on estrogen metabolism are increasingly becoming a focus of scientific research

Microbiome, Brain and Hormones: An Interconnected System

The microbiome is in constant communication with the brain and the hormonal system. This connection — known as the gut-brain axis — is mediated through neural pathways, immune signaling molecules, and metabolic products produced by gut bacteria.

Simply put, the gut can influence processes related to stress regulation, emotional stability, and mood. At the same time, hormones and psychological stress can also affect the microbiome.

This creates a highly interconnected system in which all components continuously influence one another.

Stress and the Microbiome: A Well-Studied Connection

Studies show that chronic stress is associated with changes in the microbiome. Observed changes include:

• reduced microbial diversity
• shifts in gut flora composition
• alterations in gut barrier function
• activation of the stress response system (HPA axis)

Research also suggests that these changes may in turn be linked to altered stress processing and increased emotional sensitivity.

This creates a dynamic interplay: stress affects the gut, while changes in the gut can modulate stress responses

PMS and PMDD: When the System Becomes More Sensitive

In PMS (Premenstrual Syndrome) and especially PMDD (Premenstrual Dysphoric Disorder), studies suggest that hormonal fluctuations alone are not the decisive factor. Rather, it is the individual nervous system’s sensitivity and response to these hormonal changes that appears to play a major role.

Research in affected women has identified associations with:

• altered regulation of neurotransmitters such as serotonin
• increased stress sensitivity
• signs of inflammatory processes
• possible changes in gut barrier function

The microbiome is also being investigated as a potential modulating factor. Initial studies show differences in microbial composition in women with PMS compared to control groups, although the current data remains heterogeneous.

Menopause: Hormonal Transition and the Microbiome

During menopause, the ovaries reduce their production of the female sex hormones estrogen (particularly β-estradiol) and progesterone.

Early studies indicate differences in the microbiome between postmenopausal women and women before menopause, as well as associations between dysbiosis, inflammatory processes, and common symptoms such as mood swings, sleep disturbances, and cognitive changes like “brain fog.”

Importantly, these relationships are currently described mainly as associative. The causal mechanisms have not yet been fully clarified.

The Estrobolome: The Interface Between Gut and Hormones

The estrobolome refers to the group of gut bacteria involved in estrogen metabolism.

A key role is played by the enzyme β-glucuronidase, which can reactivate estrogen metabolites excreted into the gut, essentially allowing them to be recycled.

Studies show that:

• the activity of these enzyme systems can vary greatly between individuals
• the microbiome is fundamentally linked to estrogen metabolism
• nutrition and lifestyle can influence these processes

Whether these mechanisms directly contribute to PMS or menopausal symptoms has not yet been conclusively demonstrated.

Why These Connections Matter

Overall, research increasingly points toward an integrated perspective: hormones, the nervous system, the immune system, and the microbiome are all closely interconnected.

Current research focuses less on isolated cause-and-effect relationships and more on the interaction of multiple systems that may vary greatly from person to person.

This perspective helps explain why PMS and menopausal symptoms are experienced so differently among women and why purely hormonal explanations are often insufficient.

Against this background, it becomes clear that not only hormonal processes, but also lifestyle factors, stress regulation, and nutrition may influence the microbiome — and potentially women’s emotional well-being as well.

What You Can Do to Support Your Microbiome and Mental Balance

Nutrition as the Foundation

A high-fiber diet is considered a key foundation for a diverse microbiome. Particularly beneficial are vegetables, fruits, legumes, whole grains, and seeds.

Fiber serves as a food source for gut bacteria and promotes the production of short-chain fatty acids such as butyrate and acetate, which have been associated with:

• anti-inflammatory effects
• a stable gut barrier
• improved mood and sleep quality
• reduced sleep disturbances

Eating behavior itself also matters. Mindful eating, thorough chewing, and distraction-free meals support digestion and may indirectly benefit both the microbiome and overall well-being.

Prebiotics and Probiotics

Beyond general nutrition, research is increasingly focusing on specific components that may positively influence the microbiome.

Prebiotics are indigestible food components that serve as nourishment for beneficial gut bacteria. These include:

• inulin (found in chicory, onions, or Jerusalem artichokes)
• oligofructose from vegetables and legumes
• resistant starch, for example in cooled potatoes or rice

Studies show that a prebiotic-rich diet is associated with increased production of short-chain fatty acids.

Probiotics are live microorganisms that may provide health benefits when consumed in sufficient amounts. Fermented foods are an important natural source because they contain live lactic acid bacteria. Examples include yogurt, kefir, sauerkraut, and kimchi.

 

Polyphenols and Plant Compounds

Foods such as berries, green tea, olive oil, cocoa, and various herbs contain polyphenols.

These bioactive plant compounds can act as substrates for certain gut bacteria and have been associated in studies with positive effects on microbial diversity.

Stress Reduction as a Biological Factor

Chronic stress closely interacts with the microbiome. Studies show that prolonged psychological stress is associated with:

• changes in gut flora
• increased intestinal permeability
• activation of the body’s stress response system

Practices such as regular movement in nature, yoga, mindful breaks, healthy sleep habits, and mental recovery may therefore support not only the nervous system but also indirectly benefit the microbiome.

 Exercise

Regular physical activity has been linked in studies to increased microbiome diversity and improved regulation of the body’s stress systems.

Both endurance and strength training appear to have positive effects, particularly when performed consistently over the long term.

Conclusion

PMS, PMDD, and menopausal symptoms do not arise from a single factor, but rather from a complex interaction of multiple biological systems.

The microbiome — and particularly the estrobolome — is at the center of current research because of its potential connection to hormonal, immunological, and neurobiological processes.

Although many mechanisms are not yet fully understood, current evidence clearly shows that the gut, hormones, brain, and stress system are closely interconnected.

This understanding opens new perspectives on how physical and emotional health during hormonal transition phases can be viewed and supported together.