The foods children eat during their earliest years may matter for more than their growth and physical health. New research suggests that a diet containing a greater proportion of ultra-processed foods may be associated with differences in the developing brain. In a prospective study published in the American Journal of Clinical Nutrition, researchers found that children who consumed more ultra-processed foods from infancy through early childhood tended to have smaller volumes in several subcortical brain regions by age 6.

The findings add to growing concern about the role of highly processed foods in childhood nutrition, while also highlighting an important distinction: the study found an association, not proof that ultra-processed foods directly cause changes in brain structure. Because the brain undergoes rapid development during early childhood, researchers say more work is needed to understand whether particular foods, nutrients, additives, metabolic effects or other factors explain the relationship.

What the New Study Found

Researchers followed children from infancy and assessed their diets at multiple points between 6 and 72 months of age. They then used MRI scans to examine brain structures at approximately 6 years old.

The study found that greater cumulative intake of ultra-processed foods was associated with lower volumes in several subcortical regions, including the accumbens, amygdala, pallidum, putamen and thalamus. According to the researchers, a 10-percentage-point increase in cumulative ultra-processed-food intake was associated, on average, with a 1.92% lower subcortical brain volume.

Interestingly, the researchers did not find an association between cumulative ultra-processed-food intake and measured cognitive performance at ages 2 or 6. That means the results should not be interpreted as evidence that children who eat more ultra-processed foods necessarily have lower intelligence or impaired thinking abilities.

Why Brain Development Makes Nutrition Important

Early childhood is a period of substantial brain growth. The developing brain requires adequate energy and nutrients, including protein, essential fatty acids, vitamins and minerals.

Ultra-processed foods can vary considerably, but many are formulated to be highly palatable and may contain substantial amounts of added sugars, sodium and unhealthy fats while providing less fiber and fewer essential nutrients than minimally processed foods. Harvard Health notes that ultra-processed foods commonly include items such as sugary cereals, packaged baked goods, processed meats, microwave meals and other ready-to-eat products.

Mayo Clinic likewise distinguishes ultra-processed foods from foods that undergo simpler forms of processing. It recommends practical substitutions such as choosing whole-grain cereals, fresh fruits and vegetables and less highly processed snacks.

What Are Ultra-Processed Foods?

Not every processed food is automatically unhealthy. Freezing vegetables, pasteurizing milk, cooking food or canning certain products are examples of processing that can preserve food or improve safety.

Ultra-processed foods are different because they typically contain industrially formulated ingredients and additives designed to alter flavor, texture, appearance or shelf life. Examples can include sugary breakfast cereals, packaged cookies, candy, chips, instant meals, sweetened drinks and some processed meats.

UC Davis Children’s Hospital notes that ultra-processed foods account for a substantial share of children’s calorie intake and emphasizes making practical dietary changes rather than treating nutrition as an all-or-nothing issue.

Could Ultra-Processed Foods Affect the Brain?

Scientists do not yet have a definitive answer. Several explanations are being investigated.

One possibility is nutritional quality. If ultra-processed foods replace fruits, vegetables, whole grains, legumes, nuts, eggs, fish and other nutrient-rich foods, children may receive fewer nutrients important for normal development.

Another possibility involves metabolic and inflammatory effects. Ultra-processed foods can be high in added sugars, refined carbohydrates, saturated fats and sodium. Researchers have also proposed that additives, changes to the gut microbiome and metabolic disturbances could influence brain health. Reviews of existing research have identified several possible pathways but emphasize that the biological mechanisms remain uncertain.

Healthline similarly notes that diets high in ultra-processed foods have been associated with factors such as inflammation and poorer brain health, although the strength of evidence varies depending on the outcome being studied.

The Findings Need to Be Interpreted Carefully

The new research is important, but it does not establish cause and effect. Children who consume more ultra-processed foods may differ from other children in numerous ways, including overall dietary patterns, household circumstances, physical activity, sleep and other environmental factors.

The researchers themselves say additional studies are needed to determine the mechanisms behind the associations and to establish whether particular periods of childhood are especially important. They also point out that more research is needed to understand the long-term implications of the observed brain-volume differences.

That caution is particularly important because a smaller measured brain region is not automatically equivalent to a health problem. Brain structure is complex, and researchers cannot determine the functional significance of these differences from this study alone.

What Parents Can Do

The findings do not mean parents need to eliminate every packaged or processed food from a child’s diet. Instead, they reinforce the value of building meals and snacks around minimally processed, nutrient-rich foods whenever practical.

Simple choices can include fresh or frozen fruits and vegetables, whole grains, beans, eggs, fish, yogurt without excessive added sugar, nuts or nut butters when age-appropriate, and other foods that provide important nutrients. Highly processed snacks and sweetened drinks can be offered less often rather than becoming everyday staples.

A gradual approach may also be more realistic for families. Replacing one highly processed snack with fruit, swapping a sugary breakfast cereal for a less sugary whole-grain option, or offering water instead of a sweetened beverage can make a meaningful difference without requiring a perfect diet.

A Reason for Further Research, Not Panic

The emerging evidence gives scientists another reason to examine how early-life nutrition may interact with brain development. The latest study is notable because it moves beyond questionnaires about health or behavior and examines measurable differences in brain structures using MRI.

Still, the takeaway should be balanced. The research does not show that ultra-processed foods directly shrink children’s brains, nor does it establish that avoiding these foods will prevent neurological problems. Instead, it adds to a broader body of evidence supporting diets rich in minimally processed and nutrient-dense foods during childhood.

For parents, the practical message is straightforward: focus on dietary quality and variety, limit reliance on ultra-processed foods, and avoid unnecessary alarm over occasional treats. As researchers continue studying the connection between childhood nutrition and brain development, a balanced diet remains one of the most practical ways to support children’s overall health.

Sources:

1. Harvard Health — What are ultra-processed foods and are they bad for our health?
2. Mayo Clinic News Network — What you should know about processed, ultra-processed foods
3. UC Davis Health — Ultra-processed foods
4. Healthline — What Are the 7 Worst Foods for Your Brain?
5. Medical News Today — Ultra-processed foods increase ‘bad’ fatty acids in blood

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