A study from Virginia Tech has demonstrated that ultraprocessed foods (UPFs) affect human metabolism and brain reward systems independently of their nutritional content. The research, published in Nature Metabolism, involved controlled feeding and neuroimaging to compare meals that were nutritionally similar, differing by less than 1% in calories, carbohydrates, fats, proteins, fiber, water, and salt.
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Despite these similarities, meals that were ultraprocessed resulted in significantly higher insulin surges and altered carbohydrate utilization, as well as variations in brain activity within the ventral striatum and nucleus accumbens during evaluations of food cues.
Key findings include
- Participants consuming the ultraprocessed meal experienced greater insulin spikes and maintained elevated blood glucose levels longer than those who ate minimally processed foods.
- Differences in carbohydrate oxidation after meals were correlated with changes in brain activation patterns when participants were exposed to food images during fMRI scans.
The study challenges long-standing assumptions in nutritional science, which posited that foods with the same macronutrient composition would have similar biological impacts. The findings highlight a potential link between diets high in ultraprocessed foods and increased risks for conditions like type 2 diabetes and cardiovascular issues, as these foods have become dominant in the American diet.
Senior author Alex DiFeliceantonio expressed concern over the health effects associated with high consumption of ultraprocessed foods, emphasizing the need to understand how food processing itself might alter metabolic and brain functions, beyond mere calorie content.
In the study, 57 healthy adults participated in tests where they consumed 300-calorie meals categorized as either minimally processed or ultraprocessed, following a fasting period. The minimally processed meal included items like a banana and boiled egg, while the ultraprocessed meal contained processed snacks and deli meats.
Participants were monitored for metabolic responses in a metabolic chamber, which tracked energy expenditure and blood samples post-consumption. Results displayed a significant divergence in all metabolic metrics, particularly indicating a higher insulin response to the ultraprocessed meal.
Furthermore, neuroimaging results revealed changes in reward centers of the brain, suggesting that even if participants did not consciously prefer ultraprocessed foods, their underlying brain activity reflected metabolic differences.
Carlos A. Monteiro, a public health professor and the creator of the NOVA classification system, remarked on the importance of the study as it provides experimental evidence that food processing can have distinct effects on both metabolic regulation and eating behavior.
The authors note that further research is needed to investigate the components of industrial food processing that disrupt metabolic and neural responses, and how they may contribute to long-term health outcomes.
This research was funded by the National Institutes of Health and a National Science Foundation graduate research fellowship. The findings are a significant step toward understanding the impacts of food processing on health.