Higher ultraprocessed food (UPF) consumption was associated with greater dorsal striatal responses to food cues, which were linked to subsequent increases in body mass index (BMI) and body fat percentage (BFP) among children of healthy weight.
Investigators analyzed data from 46 children of healthy weight participating in the longitudinal BrainChild cohort, recruited through Kaiser Permanente Southern California. Participants were aged 7 to 10 years at enrollment, with a mean age of 8.7 years, and 26 (56.5%) were female. Baseline assessments conducted between April 2015 and June 2024 included dietary recalls, functional magnetic resonance imaging, and anthropometric measurements. Follow-up adiposity assessments were conducted approximately 1 year later, through June 2025.
The primary analyses examined associations between habitual UPF intake and brain responses to food vs nonfood cues in the dorsal and ventral striatum. Subsequent analyses assessed 1-year changes in BMI, BFP, and waist circumference. The investigators determined UPF intake from 2 separate 24-hour dietary recalls using the NOVA classification system. Functional magnetic resonance imaging was performed following an overnight fast and subsequent glucose administration to standardize satiety. Regression models adjusted for age, sex, baseline BMI, total caloric intake, and prenatal exposure to gestational diabetes.
At baseline, UPFs accounted for an average of 67.7% of participants' daily caloric intake. Higher UPF consumption was associated with greater dorsal striatal responses to food cues after adjustment for relevant covariates. No statistically significant association was observed in the ventral striatum.
Greater dorsal striatal responses at baseline were associated with larger increases in BMI and BFP over approximately 1 year. Both associations remained statistically significant after adjustment for baseline characteristics and caloric intake. Dorsal striatal responses were not significantly associated with changes in waist circumference. Across the cohort, mean BMI increased by 1.0, BFP by 0.8 percentage points, and waist circumference by 3.9 cm.
Higher baseline UPF intake was also associated with greater increases in waist circumference over follow-up. Associations between UPF consumption and subsequent changes in BMI and BFP were positive but did not clearly reach statistical significance.
After accounting for dorsal striatal responses, the estimated association between UPF intake and subsequent BMI and BFP gains was attenuated by 31% and 44%, respectively. However, the investigators did not conduct a formal mediation analysis because of the small sample size.
Exploratory functional connectivity analyses showed that higher UPF intake was associated with increased connectivity between the dorsal striatum and the left precuneus and insular cortex during food-cue viewing, along with reduced connectivity between the dorsal striatum and the left nucleus accumbens. Higher UPF intake was also associated with increased connectivity between the ventral striatum and intracalcarine cortex. These patterns may reflect differences in neural circuits involved in food-related sensory processing and cue-driven food motivation.
"Together, these frameworks suggest that greater UPF consumption in children may be associated with motivational and habit-based neural processes rather than reflecting hedonic valuation alone," wrote lead study author Jasmin M. Alves, PhD, of the Keck School of Medicine at the University of Southern California, Los Angeles, and colleagues.
In post hoc analyses, added sugar intake was not significantly associated with dorsal or ventral striatal responses to food cues. However, additional adjustment for added sugar attenuated the association between UPF intake and dorsal striatal responses, which was no longer statistically significant. UPF and added sugar intake were modestly correlated, indicating that UPF consumption captured dietary variation beyond added sugar alone.
The study was limited by its small sample of 46 children, which reduced statistical power and raised concerns about the reproducibility of neuroimaging findings. Dietary assessments relied on participant and parent recall, and brain responses were measured at only 1 time point. The food-cue task did not account for individual food preferences or assess behavioral reward sensitivity. Food insecurity was also not evaluated. Restricting the cohort to children of healthy weight also limits generalizability to children with overweight or obesity. Additionally, the observational design precluded causal inference, as children with greater underlying striatal reactivity may have been more likely to consume UPFs rather than developing heightened responses because of their dietary intake.
The findings do not establish whether UPF consumption alters brain reward responses or whether modifying UPF intake would prevent adiposity gain. The investigators called for larger longitudinal studies incorporating repeated neuroimaging assessments to clarify the direction of these relationships and determine whether neural differences persist over time.
The authors reported no conflicts of interest.
Source: JAMA Network Open
