Unlocking the Gut-Brain Axis: How Faecal Loading Fuels MCAS and POTS

By Dr Hazel Batten, Integrative GP at Remede Wellness Medicine

(Inspired by Dr Rebecca Ryan’s presentation at The Health Lodge, Byron Bay)

Listening, Learning, and Integrating

As an integrative GP, I’m fortunate to care for a group of deeply informed, curious, and engaged patients. They often bring me new research, podcasts, and lectures that spark fresh insights and challenge me to keep learning.

Recently, one of my patients shared a talk by Dr Rebecca Ryan, a gastroenterologist with extensive experience in complex gut–brain disorders. Her presentation at The Health Lodge in Byron Bay explored the role of faecal loading in conditions such as Mast Cell Activation Syndrome (MCAS) and Postural Orthostatic Tachycardia Syndrome (POTS) — and it resonated immediately.

This perspective has genuine clinical relevance. It’s one I’ll be weaving into my practice, especially when working with patients whose overlapping gut, immune, and autonomic symptoms haven’t fully responded to standard approaches.

The Gut–Brain Connection: More Than “Just Digestion”

The gut and brain communicate constantly through a network of nerves, hormones, and immune signals — the gut–brain axis. When this relationship falters, the impact can ripple through multiple systems: mood, energy, digestion, cardiovascular stability, and inflammation.

Dr Ryan’s lecture unpacked how dysfunction along this axis can amplify conditions like MCAS and POTS, and how an under-recognised factor — faecal loading — can quietly perpetuate that dysfunction.

Understanding Faecal Loading

Faecal loading refers to the retention of stool within the bowel, even in patients who report regular bowel movements. It’s not simply constipation. Residual stool can linger in the colon, stretching the bowel, disrupting motility, and altering the microbial environment.

Over time, this can create a “stuck” system — one that recycles inflammatory mediators, affects nervous system tone, and drives systemic symptoms. For many patients, especially those with MCAS or POTS, this overlooked mechanism may explain persistent fatigue, flushing, bloating, and brain fog.

How Faecal Loading Fuels MCAS and POTS

Dr Ryan described several pathways linking retained stool to worsening symptoms:
•    Reduced motility: Stagnant contents disrupt enteric nerve function and microbial balance.
•    Systemic inflammation: Reabsorption of bacterial by-products activates immune pathways.
•    Mast cell activation: Local inflammation within the gut wall triggers histamine release and systemic hypersensitivity.
•    Autonomic dysfunction: Gut distention and microbial metabolites alter vagal and sympathetic tone, worsening orthostatic intolerance.

When motility slows, the gut–brain–immune dialogue becomes distorted, driving a vicious cycle of inflammation and dysregulation.

The Gut–Brain–Immune Triad

MCAS and POTS rarely exist in isolation. They often sit at the intersection of gut, immune, and nervous system imbalance.

Stress, dietary triggers, dysbiosis, and post-viral changes (including post-COVID syndromes) can all feed into this loop. The result: chronic inflammation, altered neuro-signalling, and persistent autonomic instability.

This interconnected model reminds clinicians that symptom management alone isn’t enough — we need to identify and address underlying physiological drivers.

Clinical and Practical Implications

Dr Ryan’s approach encourages clinicians to “clear the gut before treating the complexity.” For many patients, this means starting with fundamental gut care before moving into more advanced interventions.

Clinical priorities may include:
•    Assessing for faecal loading using history, examination, or imaging.
•    Restoring bowel motility through hydration, fibre (as tolerated), osmotic agents, or prokinetics.
•    Reducing inflammation via anti-inflammatory diets, microbial support, and gentle detoxification.
•    Supporting the vagus nerve and parasympathetic tone through breathing, mindfulness, or physical therapies.
•    Collaborative care involving gastroenterology, integrative medicine, nutrition, and psychology.

For patients, these strategies are tangible — focusing on restoring healthy elimination, calming the nervous system, and supporting the body’s natural rhythm of flow.

Rethinking Complex Syndromes

Dr Ryan’s message is both elegant and practical: sometimes the biggest breakthroughs come from addressing what seems most basic.

By tackling faecal loading and restoring gut motility, clinicians may reduce inflammatory load, stabilise mast cell activity, and ease autonomic symptoms — helping patients move from “stuck” to more stable, connected physiology.

A Note on Evidence and Caution

This framework reflects integrative clinical reasoning supported by emerging evidence, but formal guidelines are still evolving. Faecal loading and motility disorders should be properly assessed by qualified practitioners before any intervention begins.

As always, treatment must be individualised — respecting each patient’s physiology, history, and capacity for change.

Final Thoughts

This talk was a timely reminder of how powerfully interconnected the gut and brain truly are. In a world of complex syndromes and overlapping diagnoses, sometimes the path to healing starts with restoring one of our most fundamental functions: elimination.

When we help the gut move, the whole system often follows.