New human gut–brain research
What new gut–brain research reveals about the wisdom we already carry
A new human study from the University of Surrey and the University of Roehampton, published in Molecular Psychiatry, has brought us closer to understanding something I have felt in my work for years: the gut and brain are not separate territories. They are participants in one living conversation.
The study found that the neuroactive potential of bacteria living in the human gut was associated with levels of key chemicals in specific regions of the brain. It is an important step because so much of the detailed evidence connecting the microbiome with brain chemistry has previously come from animal and preclinical research.
61 young women
Healthy participants aged 17–25 completed brain imaging and provided stool samples.
GABA and glutamate
Researchers estimated two important brain chemicals across three different regions.
Microbial potential
Sequencing identified microbial genes capable of participating in neuroactive pathways.
What did the researchers discover?
Researchers used proton magnetic resonance spectroscopy to estimate two key neurotransmitters: GABA and glutamate. GABA predominantly dampens neural activity, while glutamate promotes excitation. The relationship between them contributes to the delicate excitatory and inhibitory balance involved in cognition, emotional regulation and neuroplasticity—our brain’s capacity to adapt and form new connections.
At the same time, the team analysed the participants’ stool samples using shotgun metagenomic sequencing. This allowed them to identify the genetic capacity of the gut-microbial community to carry out pathways involving GABA, glutamate, short-chain fatty acids and other potentially neuroactive compounds.
What they found was not one tidy, uniform highway between gut and brain. It was something far more alive than that. Different brain regions showed different relationships with microbial pathways.
The inferior occipital gyrus showed the broadest set of associations, including pathways involved in glutamate breakdown, GABA metabolism and short-chain fatty acids. The anterior cingulate cortex showed a distinct pattern involving glutamate and propionate pathways. The dorsolateral prefrontal cortex, a region involved in cognitive control and emotional regulation, showed a more selective association involving a microbial GABA-production pathway.
The researchers also found associations between certain microbial pathways and self-reported anxiety, depressive symptoms and sleep quality. These findings do not mean that one particular bacterium caused those experiences. They provide more specific clues about which microbial functions may be relevant to gut–brain communication.
The gut–brain axis is not one simple pathway acting uniformly. It is a conversation, happening through many biological channels at once.
What the study can—and cannot—tell us
- It found associations between microbial genetic pathways and brain chemistry.
- It did not prove that gut bacteria caused changes in GABA, glutamate, anxiety, mood or sleep.
- It measured the microbiome’s genetic potential rather than directly measuring the metabolites produced.
- It was a cross-sectional study of a small and specific participant group.
- It did not investigate colon hydrotherapy or Rojas Colon Hydrotherapy®.
Beyond a mechanical view of the body
I want to sit with this for a moment, because I think it points to something bigger than one study.
For a long time, we have been taught to think of the body as a collection of separate systems, each with its own job, each to be measured, managed and, when it misbehaves, corrected. The gut digests. The brain thinks. The heart pumps. Fix the part that is broken and move on.
That mechanical view has given us a great deal. But it can also leave people feeling that their body is something to control rather than something to understand and listen to.
What this research invites us to see is that the body is not merely a collection of physiological processes. It is biology: living, responsive and interconnected. The digestive environment and microbial community may participate in the wider biological conditions through which we experience cognition, emotion and regulation.
There is not a gut operating in complete isolation over here and a brain operating independently over there. There is a living network of communication, and the gut is one of its active voices.
What I mean by bioharmony
Bioharmony is the principle of approaching the body as an intelligent, self-regulating system rather than something to force into compliance. It asks us to notice relationships, patterns and signals instead of reducing every experience to one isolated part.
The gut and brain communicate through several routes at once. The vagus nerve carries signals between them. Immune signalling is shaped partly through the intestinal environment. The intestinal wall is a selective, living barrier, continually regulating what passes between the gut and the wider body. Microbial metabolites may also participate in these broader signalling pathways.
Long before spectroscopy allowed researchers to estimate GABA and glutamate in the living brain, many body-wisdom traditions regarded the gut as relevant to intuition, emotion and regulation—not only digestion. Modern research does not prove every traditional explanation, but it is giving us a more detailed biological vocabulary for exploring the connections people have sensed for generations.
Where Rojas Colon Hydrotherapy® fits
When we provide Rojas Colon Hydrotherapy®, we work from the understanding that bowel function exists within the whole person. Our approach is slow, therapist-led and individualised, with a focus on bowel function, comfortable elimination, hydration awareness, education and helping clients reconnect with their body’s signals.
The important scientific boundary
This new study did not examine colon hydrotherapy, so it cannot show that Rojas Colon Hydrotherapy® changes the microbiome, GABA, glutamate or mental health. We share it because it enriches the wider conversation about the body’s interconnectedness—not because it proves a treatment outcome for our service.
For me, the study reinforces a guiding principle rather than validating a specific procedure: the digestive system deserves to be approached as part of a whole living person. Where clients are already receiving medical, allied-health, mental-health or integrative care, we value communication and a multidisciplinary approach. You can read more about that commitment on our Health Professionals page.
A bridge between research and body wisdom
This is the matrix of health I teach and practise within: the recognition that nothing in the body operates alone, that wellbeing is relational rather than purely mechanical, and that the more precisely science looks, the more complexity it finds.
The bridge between mainstream gut-health research and a deeper understanding of the body’s intelligence is not as wide as it once seemed. Studies like this one help us explore that bridge—one brain region, one microbial pathway and one carefully framed question at a time.
With grace and gratitude,
Suzy
Continue exploring the gut–brain conversation
Read our plain-language evidence hub or learn more about the practitioner-led Rojas approach.
Frequently asked questions
What is the gut–brain axis?
The gut–brain axis describes two-way communication involving the digestive system, microbiome, nervous system, immune system, hormones and metabolism. It is not one single pathway, and scientists are still investigating how its different parts interact.
Did this study prove that gut bacteria control mood?
No. The researchers found associations between selected microbial pathways, brain chemistry and psychological measures. The study design cannot establish that gut bacteria caused changes in mood, anxiety or sleep.
What are GABA and glutamate?
GABA and glutamate are important chemical messengers in the brain. GABA predominantly dampens neural activity, while glutamate promotes excitation. Their relationship contributes to excitatory and inhibitory balance in the brain.
Was Rojas Colon Hydrotherapy® studied?
No. The research did not investigate colon hydrotherapy. It cannot be used as evidence that Rojas Colon Hydrotherapy® changes the microbiome, brain chemistry, anxiety, depression or sleep.
Why is this research relevant to Bottoms Up Colonics?
It contributes to the broader understanding that digestive health operates within an interconnected biological system. This aligns with our whole-person and multidisciplinary philosophy, while remaining separate from evidence about the effects of colon hydrotherapy itself.
Sources
- Johnstone N, Cohen Kadosh K. Empirical evidence for gut microbial influence on human brain neurochemistry via the gut–brain axis. Molecular Psychiatry. Published 25 August 2026. doi:10.1038/s41380-026-03813-y.
- University of Surrey. Gut bacteria linked to key brain chemicals in first-of-its-kind human study. Published 1 September 2026.
- National Library of Medicine. PubMed record for the study.
