Feeding the growing brain

Richard Moore
4 days ago
15 min read

Mental health and diet in children: how everyday nutrition shapes mood, focus and resilience from toddlerhood through adolescence

Think about the last time you felt genuinely anxious. Chances are, your appetite went with it. That connection, so obvious to adults in retrospect, works in both directions, and in children it runs even deeper. What a child eats does more than fuel their body. Alongside sleep, relationships, movement, health, and the wider environment, nutrition can support the biological systems involved in brain development, concentration, and emotional regulation.

This is not a simple message. Nutrition is not a cure for childhood anxiety or depression, and it would be wrong to frame it that way. But the science increasingly shows that what lands on a child's plate is one of the most modifiable influences on their mental health, at every stage from toddlerhood through adolescence. The aim here is to lay out what the research actually says, translate the complicated parts, and offer realistic ways to use it, without adding guilt to an already long parental to-do list.

The gut-brain connection - what your child's gut is saying to their brain

Before we look at specific foods, it helps to understand the system we are trying to support. The gut and the brain are in constant, two-way communication through a network called the gut-brain axis. This involves the vagus nerve (a long, winding nerve that runs from the brainstem down to the abdomen), immune signalling molecules, and microbial metabolites that pass between the two organs in both directions (Jiang & Li, 2025).

One of the most discussed aspects of this system involves serotonin, a neurotransmitter associated with mood and emotional steadiness. A well-known and often surprising fact is that roughly 90% of the body's serotonin is produced in the gut, by specialised cells lining the intestinal wall (Xu et al., 2025). However, this gut-derived serotonin does not cross the blood-brain barrier and travel directly to the brain. Instead, the gut influences the brain's own serotonin production through indirect pathways: by regulating the supply of tryptophan (serotonin's raw material, which does cross the blood-brain barrier), by sending signals through the vagus nerve, and by modulating immune and inflammatory activity (Xu et al., 2025; Moretti et al., 2025). A 2025 study in Cell Reports identified specific gut bacterial strains that produce serotonin locally and stimulate the nerve networks that carry these signals upward (Moretti et al., 2025).

Sitting inside the gut is the microbiome: the vast, diverse community of bacteria, fungi, and other microorganisms living in the intestine. A 2025 review in Frontiers in Nutrition found that gut microbiome composition is associated with childhood brain development, behaviour, and emotional regulation, particularly during the early years when the brain is developing fastest (Jiang & Li, 2025). Microbiome diversity - the richness and variety of different microbial species - appears to be especially important during this window.

How the gut-brain axis works

Gut to brain: The gut communicates upward via the vagus nerve, immune and inflammatory signalling, and microbial metabolites - including tryptophan, the raw material the brain uses to make serotonin. While most of the body's serotonin is produced in the gut, it does not travel directly to the brain; the gut shapes the brain's chemistry through these indirect pathways instead.

Brain to gut: The brain sends stress hormones (including cortisol), nerve impulses, and appetite signals downward in return.

Figure 1. The gut–brain axis is a two-way signalling network.

Trillions of microorganisms live in the gut and influence this conversation every single day. What a child eats can influence the composition and activity of those organisms, and therefore the signals involved in this two-way communication.

The microbiome acts something like the growing medium in which the brain's chemistry takes root. Thin substrate, low in variety, produces a less resilient result. Richer, more diverse conditions support stronger, steadier growth. And just as with any growing medium, what you regularly add to it shapes what can flourish there.

Ultra-processed foods - what the research shows about ultra-processed foods and the developing brain

Ultra-processed foods (UPFs) are industrially manufactured products containing additives, emulsifiers, colourings, and flavourings not typically found in a home kitchen. They now make up a substantial proportion of children's diets across the UK and much of the developed world. Understanding what the research says about their effects on a developing brain is not about demonising convenience; it is about knowing what we are working with.

A 2025 systematic review and meta-analysis published in Food Frontiers examined the effects of UPF consumption on cognition in children and adolescents and found consistent associations with poorer memory, attention, and executive function (Nguyen et al., 2025). A separate 2025 systematic review in the journal Nutrients found that children with higher UPF consumption showed significantly greater rates of anxiety, depression, and emotional dysregulation compared to peers with lower intake - though the authors note that most of the included studies were observational (Georgiou et al., 2025).

KEY FINDING A 2025 review noted that UPFs may pose a particular concern for developing brains in part because the periods of most rapid neural development - from infancy through adolescence - coincide with the years of highest UPF consumption in most children's diets (Nguyen et al., 2025; Georgiou et al., 2025).

The proposed mechanisms layer on top of each other. UPFs tend to be low in fibre, which the gut bacteria need to thrive; high in refined sugars, which are associated with blood glucose fluctuations that may affect mood, concentration, and irritability; and high in artificial additives that some emerging research suggests may disrupt the gut lining and contribute to low-grade, chronic inflammation. Inflammation in the gut may in turn influence neurotransmitter production and the development of the brain's stress response systems over time - though this pathway in children is still being characterised (Georgiou et al., 2025).

The Mediterranean pattern - the dietary pattern that has been studied more than any other - and what it consistently shows

The Mediterranean dietary pattern has been studied more thoroughly in children and adolescents than almost any other dietary framework. A 2024 systematic review in Nutrition Reviews, covering seventeen studies and thousands of children, found that higher adherence to a Mediterranean-style diet was associated with reduced rates of depression, anxiety, and behavioural problems across all age groups studied (Camprodon-Boadas et al., 2024). A 2025 meta-analysis in the same journal found associations between this dietary pattern and better cognitive performance and stronger academic outcomes (Treister-Goltzman & Peleg, 2025).

The Mediterranean diet is not a rigid prescription, and it does not require a particular geography or cuisine. It is a broad pattern: plenty of colourful vegetables and fruit, legumes, whole grains, nuts and seeds, olive oil as the primary fat, fish regularly through the week, moderate dairy, and limited processed meat and refined sugars. What makes it a useful guiding framework is that it covers most of the nutritional bases the developing brain needs - omega-3 fatty acids, polyphenols, fibre, iron, zinc, magnesium, folate, and vitamin D - often in combination and in forms the body absorbs well.

You do not need to cook Greek food. You need the underlying principle: real food, variety, colour, and enough fat and protein to support a brain that is still building itself. The specifics of how to translate this for a child who is a selective eater, or a teenager who refuses to touch a vegetable, is exactly the kind of individualised conversation that a Nutritional Therapist can help with - because one set of rules does not fit all children.

Key brain nutrients - the nutrients your child is most likely missing - and why each one matters

The Mediterranean dietary pattern matters partly because it delivers the specific nutrients the brain relies on most heavily. Several of these deserve particular attention, because insufficiencies are more common than most parents realise, and the effects on mood, focus, and emotional regulation can emerge even when routine tests show nothing unusual.

Structural fats - the fat your child's brain is built from

The brain is approximately 60% fat by dry weight, and the specific type of fat matters considerably (Li et al., 2025). Docosahexaenoic acid (DHA), an omega-3 fatty acid found mainly in oily fish and algae, is a key structural component of brain cell membranes and is involved in how efficiently neurones communicate with one another. During childhood and adolescence, when billions of synaptic connections are being laid down and selectively pruned, adequate DHA intake may be relevant to how that process unfolds.

A 2025 review in Frontiers in Nutrition found that omega-3 supplementation is associated with reductions in symptoms linked to Attention Deficit Hyperactivity Disorder (ADHD), anxiety, and mood dysregulation in children with neurodevelopmental conditions, with proposed mechanisms including inflammation reduction and neurotransmitter support (Li et al., 2025). A large trial led by Swansea University, which began in 2024, is investigating omega-3's role in supporting brain development in school-aged children without existing diagnoses (Swansea University, 2024).

For most children, regular oily fish in the diet provides a reasonable intake. Algae-based DHA supplements offer a well-tolerated alternative for children who do not eat fish. What level of intake is appropriate for a given child - especially one with existing concerns around mood, focus, or behaviour - is something a Nutritional Therapist can assess individually.

Iron - the nutrient most associated with focus - and most commonly overlooked

Iron deficiency is one of the most common nutritional shortfalls in children globally, and its effects on the brain are consistently underestimated. Iron is required for the production of dopamine, the neurotransmitter involved in motivation, focus, and reward processing. When iron stores fall, even before clinical anaemia develops, the dopamine system may be affected in ways that can show up as difficulty concentrating, emotional flatness, and fatigue.

A 2025 meta-analysis found that iron supplementation was associated with improved psychiatric and cognitive outcomes in non-anaemic children, adolescents, and young adults - suggesting that the brain may be sensitive to lower iron status even when haemoglobin levels remain within range (Fiani et al., 2025). Importantly, iron depletion at this earlier stage can be identified through blood markers such as ferritin, which is why proper assessment matters before drawing conclusions. An earlier study found that iron deficiency in infancy was associated with ADHD-like symptoms and slower cognitive processing in later childhood and adolescence (East et al., 2022).

Red meat, lentils, beans, tofu, fortified cereals, and dark leafy greens are all useful dietary sources. Vitamin C eaten alongside plant-based iron significantly increases absorption. Whether a child's iron status warrants assessment or supplementation is something a nutritional therapy practitioner can evaluate - because supplementing iron without knowing current status carries its own risks.

Zinc and magnesium - the minerals most parents have never thought about

Both zinc and magnesium are commonly low in children eating a diet heavy in processed foods, and both play important roles in how the nervous system regulates mood and sleep. Zinc is needed for the synthesis of several neurotransmitters, and low levels have been associated with increased anxiety, impulsivity, and emotional dysregulation in children (Hunter et al., 2025). Magnesium supports the gamma-aminobutyric acid (GABA) system - the brain's natural calming mechanism. Lower magnesium intake has been associated with sleep disruption, heightened irritability, and a more reactive stress response.

A 2025 review found that children with ADHD consistently show lower serum levels of both zinc and magnesium compared to neurotypical peers, and that dietary correction or supplementation appeared to support symptom management alongside other clinical approaches (Hunter et al., 2025). Good dietary sources of zinc include meat, shellfish, pumpkin seeds, chickpeas, and cheese. Magnesium is found in dark chocolate, nuts, seeds, leafy greens, and wholegrains. When there is reason to suspect insufficiency - particularly in a child who struggles with sleep, mood, or concentration - a proper assessment before supplementing is important, as the right form and level matters considerably.

Vitamin D - the sunshine vitamin - and why many children in the UK may not be getting enough

Most people know vitamin D supports bone health. Its role in brain function is less widely appreciated. Vitamin D receptors are found throughout the brain, including in areas involved in mood and stress regulation. A 2025 case-control study in Brain and Behavior found that adolescents with anxiety disorders had significantly lower vitamin D levels than their peers, with measurable improvement when levels were corrected (Linfang et al., 2025). A 2025 meta-analysis using Mendelian randomisation found an association between vitamin D deficiency and higher rates of depressive episodes in adolescents and young adults, though the authors note that causal interpretation requires further replication (Nano et al., 2025).

In the UK, sunlight exposure is insufficient for much of the year to maintain adequate vitamin D levels in many children. Current National Health Service (NHS) guidance recommends that children aged 1 to 4 take a vitamin D supplement year-round, and that most people over four consider supplementation through autumn and winter. Children who spend limited time outdoors, or who have darker skin and therefore synthesise less vitamin D from sunlight, may be advised to supplement throughout the year in line with NHS guidance. What an individual child needs depends on their current status, diet, and sun exposure, all of which a Nutritional Therpaist can help assess.

Tryptophan - the amino acid that builds the brain's mood system - meal by meal

Tryptophan is an amino acid found in protein-containing foods, and it is the raw material the body uses to make serotonin - and, unlike gut-derived serotonin, tryptophan does cross the blood-brain barrier, where it is converted into serotonin within the brain itself. Tryptophan availability is one of several factors involved in brain serotonin production (Xu et al., 2025). Foods rich in tryptophan include turkey, chicken, eggs, dairy products, oats, bananas, nuts, and seeds. Regular meals may support steadier energy and nutrient intake, but breakfast habits should be considered within the child's overall dietary pattern.

Polyphenols and resilience - why the colour on the plate changes more than just the aesthetics

Polyphenols are plant compounds found in deeply coloured fruits and vegetables, tea, herbs, spices, and dark chocolate. They are not a single nutrient but a vast family of molecules, many of which appear to act on gut bacteria, selectively supporting the species associated with healthier brain chemistry and lower levels of inflammation.

A 2025 review found that dietary polyphenols are associated with greater gut microbiome diversity, particularly supporting beneficial bacterial genera linked to improved mood outcomes and reduced neuroinflammation (Liu et al., 2025). Research published in Nutrition Reviews found that several polyphenol compounds can cross from the gut into the bloodstream and may reach the brain, where they appear to support neurotrophic factors - the proteins involved in forming and protecting neural connections (Dominguez-Lopez et al., 2024).

The practical message is a straightforward one: different colours of plant food tend to support different microbial populations. Blueberries, beetroot, red cabbage, spinach, turmeric, dark cherries, green tea, and dark chocolate are not niche adult foods. They are useful additions to a developing brain's diet, and they can start appearing on a toddler's plate in small, low-pressure amounts from very early on.

Breakfast and brain function - what happens to a child's brain when they regularly skip the first meal of the day

Breakfast has an outsized association with how a child's brain functions across the rest of the day. A 2024 Mendelian randomisation study in BMC Psychiatry found that regularly skipping breakfast was associated with higher risk of neuropsychiatric disorders, including anxiety and ADHD symptoms (Zhang et al., 2024). Mendelian randomisation is a statistical technique that uses genetic variation to strengthen causal inference beyond what standard observational studies can offer - though it does not definitively establish causation, and findings from a single study should be interpreted alongside the broader evidence. A separate large population-level study in Public Health Nutrition found that children who skipped breakfast showed lower cognitive engagement and reduced emotional stability at school, even after researchers adjusted for socioeconomic factors (Moller et al., 2022).

Several plausible mechanisms have been proposed: variations in morning energy availability, overall nutrient intake, and later eating patterns. A balanced breakfast containing a protein source may help some children with satiety and steadier energy through the morning. The composition of that breakfast matters - in ways that depend on the individual child's needs, health history, and overall diet - which is where personalised guidance can make a genuine difference.

Psychobiotics: the emerging frontier

Can specific bacteria influence how your child feels? One of the most active areas of current research is the use of specific probiotic and prebiotic compounds to support mental health outcomes - a group of approaches sometimes called psychobiotics. A 2025 review found that specific bacterial strains, including Lactobacillus rhamnosus and Bifidobacterium longum, show promising associations with reduced anxiety-related behaviour and stress reactivity in both animal models and early human trials, with some initial paediatric data beginning to emerge (Marano et al., 2025; Ramadan et al., 2025).

The paediatric evidence is still developing, and this is not yet a straightforward prescribe-and-move-on area. The appropriate strain, dose, and duration for a given child depends on their gut environment and overall clinical picture - which is exactly why this is an area where working with a practitioner makes sense, rather than reaching for whatever probiotic is on the shelf. What is consistent across the research is this: a gut microbiome supported by fermented foods and prebiotic fibre (found in onions, garlic, leeks, oats, and bananas) is associated with measurably different levels of stress hormones, neurotransmitter precursors, and inflammatory markers compared to a microbiome fed mainly on processed foods. Building these into the general dietary framework is worth doing now.

Children's mental health is shaped by many things: relationships, sleep, physical activity, school environments, and family circumstances. Nutrition is one thread in that larger picture, not the whole of it. But it is a thread that parents and carers can often influence, and the research consistently shows that it is worth influencing.

The shifts that matter most are not dramatic. More colour on the plate. A protein-containing breakfast more days than not. Oily fish appearing regularly in the week. A live yogurt alongside a meal. Gradually less reliance on highly processed snacks over time. Taken together, these changes support a gut microbiome - and through it, a brain chemistry - that gives children a better foundation for emotional resilience, focus, and wellbeing, from the toddler years through to the edge of adulthood.

If you want to understand what specifically your child needs - based on their age, their dietary history, their symptoms, and their individual biology - that is exactly what a paediatric nutritional therapy consultation is for.

Raising the bar in children's nutrition

At our Nutrition Clinic we believe every family deserves access to the best nutritional science, made genuinely usable. That is why we have launched two new resources for parents, carers, and family members.

NOW AVAILABLE Little Seed Nutritional First Aid Kit

An essential weekly resource covering month-by-month topics to support your family's nutrition at every stage of childhood, from first foods to adolescence.

Introductory offer: £7.99/month for life - first 100 sign-ups - (£9.99/month thereafter)

Find out more: younutritionclinic.com/childs-health

COMING SOON Advanced Nutrition First Aid

Short introductory modules for parents who would like expert guidance but are not yet ready to commit to one-to-one consultations. Topics span pre-pregnancy through to young adulthood, covering gut health, brain health (including neurodivergence and mental wellbeing), immune health, metabolic health, and hormonal health. Every module comes with a live Q&A session with our paediatric team.

About Jessica and Clare

Jessica and Clare are Registered Nutritional Therapy Practitioners with specialist paediatric training. Together, they support children with feeding difficulties, allergies and intolerances, reflux, autism, ADHD, ARFID, PANS, PANDAS and other complex neurological or neurodevelopmental needs. They work closely with the wider clinical team to provide thoughtful, individualised care for every child and family.

🧩 Connect with us

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Stay curious. Stay hopeful. Support your brain. 🧠

Disclaimer: This article is for informational and educational purposes only and does not constitute medical advice. Always consult with a qualified, registered medical doctor (MD) for diagnosis and treatment decisions.

References

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Moretti, C. H., Grasset, E., Zhu, J., et al. (2025). Identification of human gut bacteria that produce bioactive serotonin and promote colonic innervation. Cell Reports. https://www.cell.com/cell-reports/fulltext/S2211-1247(25)01205-7

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