Gut-Brain Axis
What is plausible, what is emerging research, and what to avoid believing about gut health and neurodevelopmental conditions.
Important to know:
What we do know
The gut and brain communicate
The gut-brain axis is real - bidirectional communication between gut and brain via nerves, hormones, and immune signals.
Gut microbiome differs in autism
Research shows differences in gut bacteria composition in autistic individuals, though it's unclear what this means.
GI problems are common in autism
50-70% of autistic children experience GI symptoms (constipation, diarrhoea, pain). These are real and need treatment.
Diet affects the microbiome
What you eat influences which bacteria thrive in your gut.
- ?Whether microbiome differences cause symptoms or are a result of them
- ?Whether changing the microbiome changes neurodevelopmental symptoms
- ?Which specific bacteria are beneficial or harmful
- ?Whether probiotics help beyond general gut health
- ?How to reliably modify the microbiome long-term
Evidence levels for common claims
GI issues in autism
GI symptoms deserve medical attention, not just dietary experimentation. If your child has persistent GI issues, see a GP or paediatrician.
| Issue | Prevalence | Notes |
|---|---|---|
| Constipation | Very common | May cause irritability and behaviour changes |
| Diarrhoea | Common | Rule out food intolerances |
| Abdominal pain | Common | May present as behaviour changes in non-verbal children |
| Reflux | Common | Can disrupt sleep and eating |
| Food sensitivities | Variable | True allergies vs sensory-based avoidance differ |
Evidence: For general gut health: moderate evidence for some strains. For ADHD/autism symptoms: limited and inconsistent evidence.
Considerations:
- •Different strains have different effects
- •Quality varies between products
- •Most research is preliminary
- •Generally safe but not regulated like medicines
- •Benefits may be strain-specific and individual
Recommendation: May help general gut health. No strong evidence for improving ADHD/autism symptoms specifically. Don't expect miracles.
Red flags to watch for
Autism is not caused by gut bacteria and cannot be cured by probiotics.
Current tests cannot reliably link gut bacteria to specific symptoms or treatments.
Leaky gut is a controversial concept with limited scientific support in this context.
No evidence these are better than basic good nutrition. Often exploitative.
Practical guidance
If your child has constipation, pain, or other GI issues, see a doctor. Don't just assume it's "autism".
Fibre from vegetables, fruit, whole grains. Variety in diet. Fermented foods if tolerated.
May help general gut health. Choose reputable brands. Don't expect ADHD/autism symptom changes.
The science isn't there yet to support most microbiome-based interventions.
This is an active research area. Evidence may change. Stay informed but sceptical.
The gut-brain axis is real, but we can't yet use it therapeutically. Research is ongoing, but current evidence doesn't support expensive gut-based interventions for ADHD or autism. Focus on general gut health through diet, and get proper medical attention for GI symptoms.
- The gut-brain connection is real but we don't yet know how to use it therapeutically
- GI symptoms in autism are common and deserve proper medical attention
- Probiotics may help gut health but don't expect ADHD/autism symptom improvement
- Be very sceptical of expensive gut-based "cures" or protocols
- Supporting general gut health through diet is reasonable