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BRS5 — Gut-Brain Axis & Enteric Nervous System

BRS5-3-7 - Vagal / ENS Signalling Modulation​

1. Mission & Overview​

Mission​

Maintain gut-to-brain nerve signalling through the vagus nerve and enteric nervous system.

Intervention Dominance: Diet-Supported — Dietary Requirements

Overview​

Specialised gut cells and nerves relay information from the intestinal contents to the brain. Experimental work identifies a fast glutamate-mediated connection to the vagus nerve. One exact bacterial strain also produced vagus-dependent responses in mice, but its human trial did not reproduce the proposed stress or cognitive benefits. These are different routes and different endpoints. [1]

  • Benefits: Gut sensory signals help the brain respond to internal conditions. Experimental nerve communication does not establish a general mood or attention benefit from probiotic or dietary intake.
  • Implementation Notes: The precise JB-1 strain and glucose sensory stimulus provide defined experimental examples. They are not recommendations to increase sugar intake or substitute generic fermented foods.
  • Biological Relevance: Nutrient sensing, microbial signalling and clinical electrical vagus stimulation are separate exposures. Regional receptor mRNA, vagal activity and human symptoms are different measurements.

2. Primary Biological Effects​

  • Lactobacillus rhamnosus JB-1 produced vagus-dependent responses in mice; its human trial did not establish stress or cognitive benefit. [1]
  • Mouse enteroendocrine cells connect to vagal neurons and use glutamate for rapid nutrient signals. [6]

3. Intervention Levers​

4. Mechanistic Basis​

Summary​

Lactobacillus rhamnosus JB-1 produced vagus-dependent responses in mice; its human trial did not establish stress or cognitive benefit. [1]

Biological process​

Retain exact strain-specific preclinical modulation without treating it as a universal nutritional requirement. [1]

Mechanism Boundary​

Nutrient sensing, microbial signalling and clinical electrical vagus stimulation are separate exposures. Regional receptor mRNA, vagal activity and human symptoms are different measurements.

Integration​

This PM contributes its specific process to its parent FM. Shared inputs do not merge distinct jobs or prove an integrated clinical outcome.

4.1 Scientific Findings (3)​

Scientific Findings and their assessments are available in Evidence & Audit.

Summary​

Direct neural-circuit experiments establish nutrient sensory transduction. JB-1 has vagotomy-sensitive mouse findings alongside a null human stress/cognition trial. Other probiotic symptom studies do not identify the same vagal route. [1] [5] [6]

5. BRS Pathways and Connections​

5.1 BRS Pathways​

No newly adjudicated pathway is established by this assessment.

5.2 Cross-BRS Mechanism Relationships​

Existing connected mechanisms remain candidates in the review history; no new downstream admission is inferred.

5.3 Local BRS Mechanism Relationships​

7. Phenome Connections​

These mappings are translational relationships, not single-mechanism outcome claims. Phenomes are emergent functional patterns supported by multiple interacting PMs across the BRAIN Framework.

No direct functional outcome relationship currently mapped.

Stage 2A/2B dietary-target assessment — 23 October 2026

ENRICHED. Nutrient-linked gut-to-brain vagal/enteric signalling.

Admit Direct Type B linoleic acid solely for experimentally demonstrated mouse intestinal fat-sensing/vagal engagement. This is not a reason to increase intake, a universal improvement in vagal tone, a human food-effect claim or an ADHD treatment. Reuse verified composition separately from experimental free-fatty-acid exposure.

New implementation: 1 dietary-input admissions (0 completed Unset candidates), 0 practices, 0 biochemical participants, 1 unscored Findings. Existing accepted inputs, source assessments, mission, KCs, Phenome relationships and scores are retained.

Source-to-claim boundary: Assessment source. Stop after adjudicating the stated material candidate and tracing supported delivery. Keep uncertain specificity, formulation, anatomical or measurement links explicit; no negative evidence is inferred from incomplete retrieval.

8. References​