Smart Starts: How Everyday Nutrients Shape Executive Function in Growing Minds

Why Executive Function Matters

Executive control—or executive function—is a set of mental skills that help children manage their thoughts, emotions, and actions. These include inhibitory control, working memory, and cognitive flexibility. Children with stronger executive function tend to perform better in school, build healthier relationships, and thrive in both personal and professional settings later in life.

Because childhood is a critical window for brain development, lifestyle choices during this time—especially nutrition—can have lasting effects on cognitive health. While much research has focused on the harm caused by nutrient deficiencies, scientists are now turning their attention to how overall diet quality may enhance executive function even in children who are not clinically deficient.

This article highlights emerging evidence on specific nutrients—such as water, dietary fiber, carotenoids, and choline—that reflect habitual diet quality and may support executive control during childhood (see Figure 1) [1].

Lutein: A Brain-Building Carotenoid

Carotenoids are colorful compounds found in fruits, vegetables, and some animal products like eggs. While some carotenoids help form vitamin A, others—like lutein and its isomer zeaxanthin—play different roles. These two belong to a subgroup called xanthophylls, which are known for protecting the retina from oxidative stress and filtering harmful blue light.

What makes lutein especially interesting is its unique accumulation in the infant brain, particularly in regions like the prefrontal cortex and hippocampus—areas critical for memory, attention, and decision-making. At the molecular level, lutein embeds itself in neural membranes, where its terminal hydroxyl groups help shield vulnerable lipids from oxidative damage [1-4].

Early Nutrition: Breast Milk versus Formula

One of the earliest opportunities to support lutein levels in infants is through breastfeeding. In preclinical studies, breastfed infant macaques showed up to 5 times more lutein deposition in the brain compared to those fed carotenoid-supplemented formula. In human infants, a double-blind trial found that breastfed babies had sixfold higher serum lutein levels than those fed either fortified or unfortified formula—highlighting the superior bioavailability of lutein in human milk.

From Retina to Cognition: The Role of MPOD

Lutein and zeaxanthin also form the macular pigment, which protects the retina and supports visual performance. This pigment’s density—known as macular pigment optical density (MPOD)—is a reliable, noninvasive marker of brain lutein levels. MPOD is believed to benefit cognition through two main mechanisms:

1. Filtering short-wave light, reducing retinal damage
2. Improving neurophysiology, possibly by reducing myelin oxidation and enhancing neural communication

In adults, supplementation with lutein and zeaxanthin has consistently improved both MPOD and executive function. Importantly, MPOD can be measured in children using a technique called heterochromatic flicker photometry, which has shown moderate reliability in preadolescents.

Lutein and Academic Performance in Children

Emerging studies in children have linked higher MPOD to better performance in reading, math, and written language, as well as overall academic achievement. MPOD has also been positively associated with accuracy on tasks that measure attention and inhibitory control, such as the modified flanker task, and negatively associated with errors in relational memory tasks.

Although intervention trials in children are still lacking, these cross-sectional findings suggest that lutein may play a meaningful role in supporting executive function during key developmental years. The evidence makes a strong case for future research—particularly randomized trials—to explore how dietary lutein influences cognitive outcomes in children.

Choline: A Structural and Functional Brain Nutrient

Choline is a vital nutrient that supports brain development and function across the lifespan. Much like lutein, it plays both structural and functional roles in the nervous system. Choline is essential for producing acetylcholine, a neurotransmitter involved in memory and attention, and for forming key components of cell membranes—phosphatidylcholine and sphingomyelin. These molecules are especially important in the myelin sheath, the protective layer that insulates nerve fibers and speeds up neural communication (see Figure 2) [1; 5-6].

When dietary choline is insufficient, levels of circulating phosphatidylcholine decline, and neural processing speed may suffer. In fact, disruptions in cholinergic signaling and membrane integrity have been linked to neurodegenerative diseases such as Alzheimer’s.

Early Development: Choline’s Role in Myelination

Choline’s importance is especially pronounced during early development. Myelination—the process of forming the myelin sheath—begins in late pregnancy, accelerates during the first 2–3 years after birth, and continues into early adulthood. A recent double-blind, randomized controlled trial found that third-trimester maternal choline supplementation (930 mg/day) improved infants’ performance on an attention task through the first 15 months of life. This task has previously been shown to predict information processing speed and IQ in childhood.

Even modest increases in choline intake during pregnancy were associated with lasting cognitive benefits, suggesting that maternal nutrition can shape early brain development in powerful ways.

Choline and Executive Function in Adults

Recent findings from laboratory research suggest that choline’s cognitive benefits extend beyond infancy. In a study of overweight and obese young adults, higher dietary choline intake was linked to more efficient neural processing. This was measured using the P300 waveform—a brain signal associated with attention and decision-making—during a modified Eriksen flanker task. Participants with higher choline intake showed lower peak amplitudes, indicating less cognitive effort was needed to resolve conflicting information.

Although this was a cross-sectional study, it adds to the growing evidence that choline supports executive control—the mental skills that help us focus, plan, and adapt—throughout life.

Research Gaps and Future Directions

Most choline research has focused on pregnancy and older adults, which makes sense given its role in myelin formation and the potential impact of abnormal methylation on neurodegeneration. However, there is a clear need for more intervention studies in children and adolescents. It remains uncertain whether meeting daily choline requirements in later childhood provides additional cognitive benefits. Understanding this could help shape dietary recommendations and public health strategies aimed at supporting lifelong brain health.

Water: The Overlooked Cognitive Ally

Water makes up 55–75% of the human body, and it is essential for transporting oxygen, nutrients, and waste throughout our tissues. Yet despite its importance, many children around the world are chronically underhydrated. A recent systematic review found that, on average, 60 ± 24% of children failed to meet their country’s recommended water intake guidelines (see Figure 1) [1; 7-8].

In laboratory studies, children’s urine osmolality—a measure of hydration—was surprisingly low even under normal conditions (ad libitum), and nearly identical to levels observed during water restriction (<500 mL of plain water per day). This suggests that many children may already be adapting to chronic suboptimal hydration, which could have implications for their health and cognitive function.

Dehydration and Brain Function

When water intake is restricted, the body experiences hypovolemia, a reduction in blood volume that can impair peripheral blood flow. In animal studies, 24-hour water deprivation disrupted cerebrovascular regulation and led to cognitive deficits. Dehydration also increases plasma osmolality, drawing water out of tissues—including the brain.

Research has shown that dehydration can reduce brain volume, as water is pulled from brain cells into the bloodstream. In adolescents, Kempton et al. demonstrated that ventricular enlargement was proportional to body weight loss following exercise-induced dehydration. Although performance on a Tower of London task remained stable, functional MRI revealed increased blood flow to the frontal lobe during dehydration—suggesting the brain had to work harder to maintain the same level of performance.

Children Are Especially Vulnerable

Children are particularly susceptible to dehydration due to their higher surface-to-mass ratio, which increases water loss. They also rely on caregivers to provide regular access to drinking water. In a recent three-condition crossover study, children who consumed >2,500 mL/day of water showed improved cognitive flexibility and working memory compared to those consuming <500 mL/day. Specifically, working memory cost—the mental effort required to hold and manipulate information—was significantly higher in the low-intake group.

These findings align with previous research showing that adequate hydration supports cognitive function in school-age children. Given that executive functions like working memory and flexibility are closely tied to academic achievement, increasing water intake may be a low-cost, high-impact intervention to support learning and mental performance throughout the school day.

Looking Ahead: Hydration and Cognitive Health

While much of the existing literature has focused on the negative effects of dehydration, there is growing interest in the potential benefits of improved hydration. More intervention studies are needed to explore how increasing water intake in children with habitually low hydration might enhance cognitive outcomes. Understanding these relationships could inform school policies, parental guidance, and public health campaigns aimed at optimizing brain function through simple lifestyle changes.

More Than Digestion: Fiber’s Expansive Role in Health

Dietary fiber is often praised for its digestive benefits, but its influence reaches far beyond the gut. These indigestible carbohydrate polymers—neither digested nor absorbed—have been linked to improvements in blood pressure, cholesterol levels, glycemic control, and insulin sensitivity in both children and adults. Yet one of the most intriguing areas of research is how fiber may affect brain health and cognitive function, particularly through its interaction with the gut microbiota.

When fiber reaches the colon, it becomes fuel for beneficial bacteria. These microbes ferment fiber into compounds like short-chain fatty acids (SCFAs), vitamins, minerals, and even neurotransmitters such as serotonin, GABA, and histamine. These microbial byproducts can be absorbed by the host and influence systems far beyond the gut—including the brain (see Figure 3) [1; 9-10].

The Gut-Brain Axis: A Two-Way Street

The gut-microbiota-brain axis is a complex communication network involving the central, autonomic, and enteric nervous systems, as well as the immune and endocrine systems. Modulating the gut microbiome through dietary fiber may influence cognition via multiple pathways—ranging from vagal nerve stimulation and HPA axis regulation to blood-brain barrier permeability and epigenetic gene expression.

The microbiome itself—defined as the collective genome of gut microbes—has been linked to mental health, body composition, and cognitive performance. Importantly, the composition of these microbial communities is highly sensitive to dietary changes, even in the short term.

Early Life: Seeding the Microbiome

In infancy, the first exposure to dietary fiber comes through human milk oligosaccharides (HMOs)—specialized carbohydrates found in breast milk. Preclinical studies have shown that HMOs can enhance hippocampal function and long-term potentiation in rodents, suggesting a role in memory formation. However, studying the impact of the infant microbiome on cognitive development remains challenging, as microbial communities fluctuate significantly until around 2 years of age, when solid foods are introduced.

Childhood: Fiber and Executive Function

In preadolescent children, higher total fiber intake—measured over a 3-day dietary record—was positively associated with attentional inhibition, a key component of executive control. Specifically, insoluble fiber and pectin, which are readily fermented by gut bacteria, were linked to better performance on tasks requiring inhibitory control. These findings suggest that fiber may help regulate cognitive processes during a critical developmental window (see Figure 3).

However, this study was cross-sectional and did not directly assess the microbiome, leaving open questions about the mechanisms involved. Future research should explore how fiber-driven changes in gut bacteria might influence cognition in children.

Later Life: Fiber and Neuroprotection

As we age, the diversity of gut microbes tends to decline, and individual variability increases. While intervention studies on fiber supplementation in older adults have yielded mixed results, some have reported improvements in mood, memory, and executive function. Observational studies have found that cognitive performance in elderly individuals correlates with microbial composition—negatively with Enterobacteriaceae and positively with Lactobacillales.

In patients with Alzheimer’s disease, recent findings suggest a microbiome dominated by gram-negative bacteria, which may contribute to neuroinflammation and cognitive decline.

Mechanisms: Butyrate and Brain Health

Among the many microbial metabolites, butyrate—a short-chain fatty acid—is particularly important. It plays a direct role in:

• Maintaining blood-brain barrier integrity
• Modulating gene transcription via epigenetic mechanisms
• Promoting neurotransmitter and hormone synthesis
• Inhibiting absorption of bacterial toxins

These effects can reduce neuroinflammation, apoptosis, and amyloid deposition, all of which are implicated in neurodegenerative diseases. A fiber-rich diet may encourage butyrate production, fostering a protective microbial environment that supports brain health.

A Dynamic Ecosystem: Diet and Microbiota

The gut microbiota is highly dynamic, influenced by diet, illness, infection, and medications. While we are still in the early stages of understanding the exact mechanisms, research into butyrate’s role in neuroprotection is promising. There is growing evidence that the gut-brain axis operates across the lifespan—from shaping immune and metabolic pathways in infancy to preserving cognitive function in old age.