The Gut–Brain Axis and PMDD: How Your Digestive Health Shapes Your Mood and Hormones

by Camilla Brinkworth, Naturopath, PMDD Specialist & Founder of PMDD Naturopath and Camilla Clare Holistic Health

When I first learned about the gut–brain axis, it completely reframed the way I approached PMDD — both personally and professionally. So many women come to me frustrated, saying things like, “I’ve tried every supplement, but my mood still crashes before my period.” Often, the missing link isn’t another pill. It’s the gut.

Why Gut Health Matters in PMDD

Your gut isn’t just a digestion machine; it’s a key player in your emotional and hormonal balance. Around 90% of serotonin — the neurotransmitter that regulates mood and sleep — is produced in the gut, not the brain. The same is true for GABA, a calming neurotransmitter that helps keep anxiety and overstimulation in check.

When the gut microbiome — that delicate ecosystem of bacteria — becomes imbalanced (a state called dysbiosis), serotonin and GABA production can drop, leaving you more vulnerable to mood swings, anxiety, and low energy during your luteal phase.

I’ve seen this repeatedly in clinic. One client, who had battled bloating and PMDD for years, began addressing her gut health with targeted probiotics and prebiotic fibres. Within a few months, not only did her digestion improve, but she described her premenstrual mood as “noticeably calmer — like my body wasn’t at war with itself anymore.”

Leaky Gut and Inflammation

Another piece of the puzzle is intestinal permeability, often called leaky gut. When the lining of the gut becomes compromised, it allows bacteria and toxins to enter the bloodstream. This triggers systemic inflammation — the same inflammation that can worsen pain, fatigue, and emotional reactivity in PMDD.

Inflammation also interferes with hormone metabolism and how neurotransmitters are processed, amplifying the sensitivity that many women with PMDD already experience.

How Dysbiosis and Hormones Interact

The gut microbiome even influences how your body metabolises oestrogen. Certain gut bacteria produce an enzyme called beta-glucuronidase, which can recirculate oestrogen back into the bloodstream instead of letting it be excreted. When this system is imbalanced, it can contribute to oestrogen dominance — one of the hormonal patterns linked with PMDD.

This is why simply balancing hormones with herbs or supplements isn’t enough. We must first ensure the gut is functioning properly to metabolise those hormones in the first place.

Healing the Gut–Brain Axis: Practical Steps

Healing the gut is one of the most foundational parts of my PMDD naturopathic protocol. Here are a few ways to start:

1. Prioritise Probiotics

Choose a broad-spectrum probiotic that supports both gut and mood health — particularly strains like Lactobacillus rhamnosus, L. plantarum, and Bifidobacterium longum. These have been shown to positively influence GABA and serotonin pathways.

2. Feed Your Microbiome with Prebiotic Fibres

Prebiotics act as food for beneficial bacteria. Foods like oats, garlic, onions, leeks, and cooked then cooled rice or potatoes are rich in prebiotic fibres that help those bacteria thrive.

3. Incorporate Fermented Foods

Add a small amount of sauerkraut, kimchi, or coconut yoghurt daily. Fermented foods not only support the microbiome but can also reduce inflammation and improve digestion.

4. Reduce Alcohol and Processed Foods

Alcohol and processed foods damage the gut lining and deplete key nutrients like magnesium and B vitamins — which are already crucial for PMDD. (You can read more about this connection in my article on alcohol’s impact on PMDD.)

5. Manage Stress

Chronic stress alters the microbiome just as much as diet does. Meditation, nature walks, and gentle movement like yoga all help restore nervous system regulation, which in turn supports healthy digestion and mood balance.

The Naturopathic Perspective: Healing the Whole Person

Naturopathy has always recognised the connection between the body’s systems — the gut, hormones, and mind are never separate. When we nurture gut health, we’re not just improving digestion; we’re supporting emotional stability, hormone balance, and nervous system resilience.

The gut–brain axis beautifully illustrates what I often tell my clients: the body doesn’t make mistakes — it communicates. When we listen with curiosity rather than frustration, we uncover the deeper causes of imbalance. Healing from PMDD is not about suppressing symptoms but restoring harmony between all parts of the system.

If you’re ready to explore how improving your gut health could transform your experience of PMDD, I offer online consultations and personalised naturopathic programmes to support your hormones, mood, and emotional wellbeing from the inside out.

Author Bio
Camilla Brinkworth is a naturopath, nutritionist, and Family Constellations facilitator specialising in PMDD and women’s hormonal health. Having personally healed from PMDD, she now supports women worldwide through her clinics — PMDD Naturopath and Camilla Clare Holistic Health — combining natural medicine, trauma-informed care, and plant-based nutrition.