Nourishing Attention: The Gut-Brain Link in ADHD - How The Microbiome Shapes Focus, Mood & Wellbeing
- Molly Brooker-Roberson
- May 13
- 5 min read
By Harpenden Kids Nutrition
For decades, Attention-Deficit/Hyperactivity Disorder (ADHD) has often been misunderstood—portrayed as a deficit in attention, a behavioural problem, or worse, a failure in discipline or parenting. But science is rapidly evolving, and so is our understanding of this complex neurodevelopmental condition.
As a nutritional therapist specialising in children's health—particularly in areas of mental health, neurodiversity, and behavioural challenges—I’ve seen first-hand how transformative it can be when we support the whole child, starting from the inside out. And when it comes to ADHD, one of the most under-valued factors is the health of the gut microbiome.
This isn’t just about symptom management. It’s about addressing the biological foundations that support focus, mood regulation, emotional resilience, and overall wellbeing—through a scientific lens that’s both compassionate and empowering.
Redefining ADHD: Beyond the Label
Let’s begin by shifting the narrative.
ADHD isn’t a behavioural flaw or a lack of willpower. It’s a neurodevelopmental difference—a variation in brain wiring that presents both challenges and unique strengths. While the media often focuses on the more difficult traits such as impulsivity, distractibility, or hyperactivity, these traits are often the flip side of creativity, innovation, and a deep, passionate focus when something truly captures attention.
The Science Behind ADHD
Genetics: Over 80% of ADHD traits are heritable. Specific genes involved in regulating dopamine, serotonin, and glutamate contribute to the way a child’s brain processes information, seeks stimulation, and manages emotional responses.
Brain Structure and Function: Research shows differences in areas such as the prefrontal cortex (involved in planning and impulse control) and the basal ganglia (key in motivation and reward processing). This helps explain why children with ADHD often do better when they are interested, engaged, or excited by a task.
Neurotransmitter Activity: ADHD is closely linked to imbalances in dopamine (the brain’s reward and motivation chemical) and norepinephrine (which helps with focus and alertness). These imbalances contribute to fluctuating attention, emotional reactivity, and sensitivity to the environment.
However, genes and brain structure are only part of the picture. A growing body of research is pointing toward another influential system that is intricately connected to brain function: the gut microbiome.
The Gut-Brain Axis: Your Child’s Second Brain
The gut is often called the "second brain"—and for good reason. Trillions of microbes residing in the gastrointestinal tract don't just influence digestion; they communicate directly with the brain, affecting mood, cognition, and behaviour through what’s known as the gut-brain axis.
This two-way communication involves:
The vagus nerve, a major nerve connecting the gut and brain.
Immune signalling, which can influence inflammation throughout the body.
The production of neurotransmitters, many of which are made or modulated in the gut.
Microbes That Make a Difference:
Dopamine Precursors: Species like Bifidobacterium and Lactobacillus support the production of dopamine—vital for motivation, attention, and goal-directed behaviour.
Serotonin Support: Around 90% of serotonin, which regulates mood and sleep, is produced in the gut. Microbes like Turicibacter influence its production.
Calming GABA: Bifidobacterium adolescentis helps convert glutamate into GABA, a calming neurotransmitter that can soothe anxiety and regulate hyperactivity.
Gut Inflammation and the “Leaky Gut” Factor
When the gut is out of balance—a state known as dysbiosis—it can lead to increased intestinal permeability, often referred to as "leaky gut." This allows partially digested food particles, toxins, and bacteria to enter the bloodstream, triggering systemic inflammation and potentially affecting brain function.
Children with ADHD are more likely to show:
Elevated inflammatory markers such as TNF-α and IL-6.
Lower levels of short-chain fatty acids (SCFAs) like butyrate, which are crucial for maintaining the integrity of the gut lining and regulating brain inflammation.
These physiological changes can exacerbate symptoms such as inattention, emotional dysregulation, fatigue, and brain fog.
What Research Says: The ADHD Gut Microbiome
Studies consistently reveal that children with ADHD often have distinct microbial profiles compared to their neurotypical peers. Here's a snapshot of what we’re seeing in the research:
These imbalances may help explain the sensory sensitivities, emotional reactivity, and cognitive fluctuations experienced by many children with ADHD.
Nutritional Strategies to Support the ADHD Gut
Supporting the gut microbiome is one of the most effective—and empowering—ways to influence your child’s brain health. Nutrition plays a critical role, and even small changes can yield significant improvements.
1. Feed the Right Microbes
Prebiotic-rich foods like garlic, onions, leeks, green bananas, and asparagus feed beneficial bacteria.
Polyphenol-rich foods—including berries, dark chocolate, and rainbow vegetables—support microbial diversity and reduce inflammation.
If you notice bloating, smelly gas, or changes in bowel movements, this may indicate underlying dysbiosis (an imbalance in gut bacteria) and could be a sign that a more tailored approach is needed.
In these cases, a stool test guided by a qualified practitioner can provide valuable insights. (See more on functional testing below.)
2. Focus on Omega-3s
Essential fatty acids from fatty fish, chia seeds, walnuts, and flaxseeds improve neurotransmitter function, reduce inflammation, and enhance cognitive performance.
3. Balance Blood Sugar
Provide protein and fibre-rich snacks to stabilise energy, improve concentration, and reduce behavioural crashes. Think boiled eggs, hummus, veggie sticks, or seed butters on wholegrain toast.
4. Incorporate Fermented Foods
Natural probiotics in foods like kefir, yogurt, sauerkraut, and miso can help re-populate the gut with beneficial bacteria, supporting mood and attention regulation.
However, if your child is new to fermented foods, it’s important to start with very small amounts—just a teaspoon at a time—and gradually increase to assess tolerance.
In these cases, a stool test guided by a qualified practitioner can provide valuable insights. (See more on functional testing below.)
5. Reduce Dietary Triggers
Minimise ultra-processed foods, flavour enhancers, and excess sugar—all of which are known to disrupt the microbiome and aggravate hyperactivity and mood swings.
Functional Testing: A Personalised Roadmap to Better Health
Every child is unique—and their microbiome is too. That’s why functional stool testing can be such a powerful tool in getting to the root of ADHD-related challenges.
I recommend tests such as:
GI360 by Regenerus Labs
GI Effects by Genova Diagnostics
These comprehensive panels assess:
Microbial diversity and composition (e.g., are beneficial species like Bifidobacterium and Coprococcus thriving or depleted?)
Inflammatory markers like lysozyme and secretory IgA, which can indicate leaky gut and immune activation.
Short-chain fatty acid production, especially butyrate—key to brain and gut integrity.
Presence of pathogens like parasites, yeast, or bacterial overgrowths that may be contributing to dysregulation or mood changes.
With this level of insight, we can create targeted, evidence-based protocols using specific probiotics, anti-inflammatory nutrients, herbal antimicrobials (if needed), and tailored dietary interventions that address your child’s unique needs—no guesswork involved.
If you're wondering whether functional testing could be helpful for your child, the best place to start is a free discovery call. This is an opportunity to explore your child’s health history and current challenges, and to discuss whether in-depth testing—such as GI360 or GI Effects—might be part of a personalised care plan.
A New Path Forward for ADHD Support
While ADHD can present real and sometimes overwhelming challenges, it also reflects a different way of experiencing and responding to the world. It means that your child’s brain and body may have different needs—and by addressing those needs holistically, we can support them to thrive emotionally, cognitively, and physically, in ways that honour their unique strengths.
Through the gut-brain axis, we have an incredible opportunity to:
Naturally balance neurotransmitters like dopamine and serotonin.
Reduce inflammation that contributes to brain fog and mood swings.
Improve focus, emotional resilience, and overall wellbeing—without harsh interventions.
How To Get Started
If you're curious about how nutritional therapy could support your child’s focus and mood, I invite you to book a free discovery call. We’ll talk through your concerns, your child’s symptoms, and whether this integrative approach is the right fit for your family.
Article References References available upon request. This blog is based on peer-reviewed research in microbiome science, neurodevelopment, and nutritional psychiatry.
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