3 Ways the Gut Makes Your Child's Anxiety Worse
Disruption in the microbiome is one of the most consistent contributors to anxiety I see in kids. In this article, I want to explain why, because most parents have no idea the gut is even part of the picture.
It's been firmly established now that the gut and the brain are in constant conversation. A highway of nerve signals runs between them, most travelling upward, from gut to brain. That means what's happening in your child's digestive system is directly shaping how calm, focused, and regulated they feel. The question is: how? And what can we do about it?
Here are three specific ways the gut can keep anxiety switched on.
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Nutrient Gaps That Starve the Nervous System
The brain needs specific nutrients like magnesium, zinc, omega-3 fatty acids, vitamin D, choline, B vitamins, and iron to produce the chemicals that keep a child calm and regulated. When these are low, it becomes harder to settle.
A 2025 review in Frontiers in Nutrition found that neurodivergent kids and kids with ADHD consistently show lower levels of key nutrients - particularly omega-3 and magnesium. They found that nutritional supplementation improved mood, reduced disruptive behaviour, and improved language, learning and attention symptoms across multiple clinical trials.
Their higher need for nutrients may stem back to genetics or poor diet, but here's where the gut comes in: even if a child eats reasonably well, poor digestion means nutrients don't absorb properly. A compromised gut lining or an imbalanced microbiome can reduce how much nutrition actually makes it into the body. A comprehensive microbiome assessment can tell us if this is happening.
Bottom Line For Parents: You can't nourish a nervous system when the digestive system isn't doing its job.
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Gut Toxins That Trigger Brain Inflammation
Harmful bacteria in the gut release toxic byproducts called lipopolysaccharides, or LPS, also known as endotoxins (toxins created inside the body).
A healthy gut can handle some endotoxins. They stay contained, causing some local inflammation but then exit through the stool. But when those LPS producers outnumber the good bacteria in the gut, LPS levels and inflammation can become quite high. When the gut lining is damaged, LPS can slip into the bloodstream and travel to the brain. At that point, they drive up systemic inflammation, which directly affects mood, behavior, and anxiety.
Animal and human research has shown that LPS directly increases anxiety-like behavior, that blocking the LPS signalling pathway reduces those behaviors, and that LPS can directly interfere with the transmission of neurotransmitters, thereby affecting mood and increasing stress reactivity.
Furthermore, the Frontiers In Nutrition article previously cited regarding nutrients also found that over 80% of the neurodivergent kids studied showed high reactivity to cow’s milk/dairy/casein, and just over half to wheat/gluten. The presence of these intolerances further suggests poor gut health, endotoxins, and gut inflammation can contribute to poor mental health and learning struggles.
Bottom Line For Parents: An unhealthy gut microbiome sends signals of threat directly to the brain, keeping the nervous system on high alert.
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Constipation and IBS That Keep the Stress Response Active
Persistent constipation, loose stools, and belly pain in kids are signals that their nervous systems are dealing with active, ongoing stress. Here’s why:
The gut is so rich with neurons that it's sometimes called "the second brain." When the bowel isn't moving regularly, or when there's pain and bloating, those distress signals felt in the gut feed directly into the brain's stress centers. The LPS previously discussed is allowed to sit in the colon and potentially slip through the irritated gut lining, the nutrient problems discussed earlier already have the nervous system on edge, plus a child feels physically uncomfortable.
Kids get stuck in a vicious cycle: anxiety makes the gut worse, and a struggling gut makes anxiety worse.
A 2025 review in BMC Pediatrics confirmed that anxiety disorders are among the most common conditions seen alongside functional gut problems in children, and that the bidirectional relationship between gut discomfort and anxiety is well-established. A separate 2025 review in Nutrients found that serotonin signaling, which is a key regulator of both mood and gut movement, is disrupted in children with IBS, linking gut dysfunction directly to anxiety and depression at a biochemical level.
I talk more about the IBS-brain-IBS-brain vicious cycle in this free masterclass.
Bottom Line For Parents: If your anxious child is chronically constipated or has ongoing tummy pain, their nervous system is working overtime just to manage it.
This is what I mean when I say there are biological roots of behavior. Anxiety doesn't just live in the mind. It lives in the gut, in the cells, in the biology. And as we shift that biology, kids are better able to find confidence and courage as they face regular stressors throughout life.
If your child's anxiety feels stuck and nothing seems to be helping, the gut is a very reasonable place to start looking. It's one of the first things I assess, and often one of the most impactful things I work on with families.
Want to understand more about how the gut may be driving your child's anxiety, focus issues, or big behaviors? Start HERE.
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Select References:
Querdasi et al. (2025). Nature Communications https://www.nature.com/articles/s41467-025-64988-6
Frontiers in Nutrition (2025) https://pubmed.ncbi.nlm.nih.gov/40808843/
Nutrients (2025) https://pmc.ncbi.nlm.nih.gov/articles/PMC11853794/
LPS in Mice: https://pubmed.ncbi.nlm.nih.gov/27192986/
LPS and neurotransmission: https://pmc.ncbi.nlm.nih.gov/articles/PMC11660149/
