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The Gut-Brain Axis: How Your Digestive Health Affects Your Mood
- Dr Titilayo Akinsola
- 12 hours ago
- 5 min read
Introduction
When we think about mood, anxiety, or depression, we tend to look “upwards”—at the brain, thoughts, feelings. But a growing body of advanced research shows there’s a two-way dialogue happening between your gut and your brain. This communication, known as the gut‑brain axis, means that your digestive tract, your microbiome (the ecosystem of microbes in your gut), your diet, your stress and your sleep all play a meaningful role in mental-health outcomes. In this post we’ll unpack:
What the gut-brain axis is
How gut health influences mood, anxiety, and cognition
The evidence base (nuanced, emerging—not panacea)
What we do at Favor Mental Health to integrate this understanding
Practical steps you or a client can take now
What is the Gut-Brain Axis?
The gut-brain axis refers to the bidirectional communication systems connecting the gastrointestinal tract and its microbiota (gut bacteria, fungi, etc.), the enteric nervous system (often called the “second brain”), the central nervous system (brain/spinal cord) and various hormonal, immune and metabolic pathways. (@WalshMedical)
Key pathways include:
Neural communication – especially via the Vagus nerve, which carries signals from the gut to the brain and vice-versa.
Neurotransmitter/metabolite production – gut microbes produce or modulate levels of serotonin, GABA, dopamine, short-chain fatty acids (SCFAs) which impact brain function.
Immune & inflammatory signaling – gut microbiome influences immune function, and gut “leaky-barrier” or dysbiosis may lead to systemic inflammation which is linked with mood disorders. (MedCrave Online)
Endocrine/metabolic pathways – the gut microbiome affects stress-hormone regulation (e.g., HPA axis), metabolism, perhaps even circadian rhythm—all of which affect mood and cognition. (MDPI)
“The gut-brain axis is a complex system of two-way communication between the digestive system and central nervous system, with implications for mental health.” — VeryWellMind
How Gut Health Affects Mood, Anxiety & Cognition
Here are the main mechanisms (and current evidence) linking gut health to mental‐health outcomes.
1. Microbiome and neurochemical production
Gut bacteria influence neurotransmitter systems. For example:
About 90% of the body’s serotonin (a key mood-neurotransmitter) is generated in the gut. (@WalshMedical)
Bacterial metabolites like SCFAs (butyrate, propionate) can influence brain signalling, gene expression and neuroplasticity. (MDPI)
This means if your microbiome is disturbed (dysbiosis), the signals your gut sends to your brain can shift from “all okay” to “alert mode”, increasing vulnerability to low mood, anxiety or cognitive fog.
2. Inflammation & immune signalling
When gut barrier integrity is compromised, or when microbial diversity is reduced, the immune system may trigger low-grade inflammation. These inflammatory signals can reach the brain, influence mood regulation, slow cognitive processing and worsen anxiety.
3. Stress-axis / HPA (Hypothalamic-Pituitary-Adrenal) and gut
Stress (psychological or physical) affects gut motility, microbial diversity and gut barrier function. In turn, gut signals modulate the HPA axis (stress-response system). When this loop is dysregulated, you may see heightened cortisol, poor sleep, anxiety and increased emotional reactivity. (@WalshMedical)
4. Lifestyle mediators
Diet, sleep, physical activity, antibiotic exposure, environmental toxins—all impact microbiome health, thus indirectly affecting mood. For example, a diet high in processed foods correlates with poorer microbial diversity and higher rates of depression. (The Times)
5. Clinical associations
Studies show that people with depression or anxiety often have altered gut-microbiome profiles (reduced beneficial bacteria, increased pro-inflammatory strains) compared to controls. (PubMed)
Animal models (germ-free mice) show that absence of a gut microbiome leads to increased anxiety-like behaviour, altered stress response. (@WalshMedical)
Early human dietary/intervention studies suggest that improving gut health (through prebiotics/probiotics/diet) may improve mood/anxiety symptoms—but evidence is still emerging.
Why This Matters for Mental Health Care
For a clinic like Favor Mental Health, this means:
When clients present with mood/anxiety/cognitive symptoms, we should consider gut health and lifestyle context in the formulation—not just neurotransmitters and talk therapy.
Recognising the gut-brain axis doesn’t replace standard treatment (therapy, medication) but complements it—offering additional levers to improve outcomes.
For clients with persistent mood/anxiety despite standard care, a gut-brain perspective offers an alternative angle to explore: diet, gut symptoms, sleep, antibiotic history, GI symptoms, microbial diversity.
This approach supports the “whole person” model: brain and body, mind and gut.
How Favor Mental Health Integrates Gut-Brain Axis in Practice
1. Intake & assessment
Ask about digestive symptoms (bloating, constipation/diarrhea, antibiotic history, food intolerances), diet quality, sleep, stress levels, lifestyle.
Include gut health questions in the mental-health history: “How is your digestion?”, “Do you notice mood changes after certain foods?”, “How was your sleep and diet before your mood shifted?”
Incorporate collaboration with nutrition/dietary specialist if gut-health issues are prominent.
2. Psycho-education
Explain to clients: “Your gut and brain are in constant conversation. Improving your gut health doesn’t guarantee a mood fix, but it gives your brain a healthier environment for healing.”
Use simple analogies: “Think of your gut-microbiome as soil for your brain’s garden. If the soil is depleted, plants (mood, focus, resilience) struggle.”
3. Intervention strategy
Dietary adjustments: Increase fiber, fermented foods, whole-food, plant-based meals; reduce ultra-processed foods, excessive sugar.
Lifestyle support: Prioritise sleep hygiene, stress reduction (because stress harms microbiome), regular physical activity, routine.
Gut-microbiome support: Consider prebiotic/probiotic options (while acknowledging evidence is still evolving).
Therapy linkage: Explore how gut/gastrointestinal symptoms may be linked to stress, anxiety, trauma; integrate behavioural interventions to support diet/sleep/gut habits.
Monitoring: Track gut symptoms + mood symptoms together. For example, note if a change in diet corresponds with improved mood or reduced anxiety.
4. Collaborative care
Work alongside the client’s primary care, gastroenterologist, nutritionist as needed.
If persistent GI dysfunction or severe dysbiosis suspected, refer for microbiome testing, GI evaluation.
Practical Steps Clients Can Take Right Now
If you’re a client or working with someone who wants to leverage the gut-brain connection, here are actionable suggestions:
Increase diverse fiber intake: Aim for vegetables, legumes, whole grains, fruits—because fiber feeds beneficial gut bacteria.
Introduce fermented/prebiotic foods: Kefir, yogurt (if dairy tolerable), kimchi, sauerkraut, garlic, onions, bananas (pre-biotic).
Limit processed/sugary foods: These promote dysbiosis and inflammation, which harm mood/cognition.
Sleep & stress hygiene: Prioritise 7-9 h good sleep, consistent schedule; use stress-management (breathing, mindfulness) because stress negatively affects gut health.
Track your gut/mood link: Keep a simple daily log for 2 weeks: note digestion (gut symptoms), mood (+/−), food type, sleep quality. Look for patterns.
Raise the topic with your clinician: “Could my gut health be affecting my mood/anxiety? What steps can we include alongside my therapy/medication?”
Be patient: Gut/microbiome changes take time (weeks to months). This is a supportive pathway, not a quick fix.
Key Takeaways
The gut-brain axis shows that digestive health isn’t just physical—it is deeply tied to emotional, cognitive and stress-response health.
Research supports multiple mechanisms (neurotransmitters, inflammation, neural signalling) by which the gut influences mood and anxiety—but the evidence in humans is promising yet emerging.
For mental-health care, recognising the gut-brain link adds depth to treatment planning, supports holistic care, and offers additional levers for improvement.
At Favor Mental Health we integrate this paradigm: gut health + brain health, nutrition + therapy + lifestyle.
While improving gut health doesn’t replace therapy/medication, it enhances the foundation on which mental recovery is built.
If you’ve noticed mood or anxiety symptoms that remain despite your current approach—or you find digestion/food/sleep problems that seem linked to how you feel—let’s explore how your gut-brain axis may be playing a part. At Favor Mental Health we’ll help you map this out, integrate gut-health strategies into your mental-health plan, and walk with you toward greater resilience and clarity. Call us at 410-403-3299 today to schedule your consult.
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