Short-term consumption of ultra-processed semi-synthetic diets impairs the sense of smell and brain metabolism in mice

The prevalence of highly-palatable, ultra-processed food in our modern diet has exacerbated obesity rates and contributed to a global health crisis. While accumulating evidence suggests that chronic consumption of ultra-processed semi-synthetic food is detrimental to sensory and neural physiology, it is unclear whether its short-term intake has adverse effects. Here, we assessed how short-term consumption (<2 months) of three ultra-processed diets (one grain-based diet, and two semi-synthetic) influence olfaction and brain metabolism in mice. Our results demonstrate that short-term consumption of semi-synthetic diets, regardless of macronutrient composition, adversely affect odor-guided behaviors, physiological responses to odorants, transcriptional profiles in the olfactory mucosa and brain regions, and brain glucose metabolism and mitochondrial respiration. These findings reveal that even short periods of ultra-processed semi-synthetic food consumption are sufficient to cause early olfactory and brain abnormalities, which has the potential to alter food choices and influence the risk of developing metabolic disease.