Ultra-processed foods may prime children’s brains to seek out rewarding food cues

USC researchers found that children who ate more ultra-processed food showed stronger reward-related brain responses to appealing food images, which helped predict later gains in BMI and body fat.

A study from the Keck School of Medicine of USC suggests that ultra-processed foods may do more than add calories: they may also alter how children’s brains respond to food. Published in JAMA Network Open, the research followed 46 children aged seven to 10 who were all a healthy weight at the start of the study. Those who consumed more ultra-processed foods showed stronger activity in the dorsal striatum, a brain region involved in reward and motivation, when they viewed appealing food images. According to the researchers, that heightened response helped explain later gains in body mass index and body fat over the following year.

The findings add a neurobiological layer to a broader body of evidence linking ultra-processed diets to poor health. Earlier work published in The American Journal of Clinical Nutrition found that higher ultra-processed food intake in early childhood was associated with smaller volumes in subcortical brain regions tied to reward, emotion and motivation, although it did not affect cognitive performance. Together, the studies suggest that highly processed diets may influence brain development in ways that extend beyond weight alone, particularly during periods when children’s habits and food preferences are still forming.

The USC researchers used functional MRI scans at baseline and compared brain responses with detailed dietary recall data. They found that greater ultra-processed food intake was associated with stronger cue reactivity in the dorsal striatum, but not the ventral striatum. That distinction matters because the dorsal striatum is closely involved in habit formation and motivated behaviour, which may help explain why some children become more drawn to highly palatable foods over time. The study also reported that dorsal striatal reactivity accounted for 31% of the link between ultra-processed food intake and later increases in BMI, and 44% of the association with higher body fat percentage.

Related research points in the same direction. A study in JAMA Pediatrics found that a more food-heavy home environment, especially one with a greater share of ultra-processed items, was associated with a stronger attentional bias towards those foods in children. Separate work in Contemporary Clinical Trials has also examined whether controlled exposure to ultra-processed diets changes reward processing and energy intake in adolescents and young adults. Taken together, these studies reinforce the idea that the food environment can shape both behaviour and biology, not just short-term eating patterns. Kathleen A. Page, the senior author of the USC paper, said the child brain is still developing and may be especially sensitive to food cues, adding that changing the food environment to make healthier, less processed choices more available is an important part of the solution.