ByMelissa Fleur Afshar
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Eating too much sugar and fat as a child could, in theory, weaken the connection between the gut and the brain for years afterward, even if the diet improves later in life, according to new research identifying a previously unknown link between digestion and memory
The study, published in Nature Communications, found that signals sent from the gut to the brainstem to the brain—play a key role in forming memories, particularly memories about food
The researchers, based at the University of Southern California (USC), say the discovery could help explain why poor diet, obesity and diabetes are linked to cognitive decline, and may point toward new treatments for conditions such as Alzheimer’s disease
Gary Brecka, a human biologist, biohacker and longevity researcher who hosts The Ultimate Human podcast, told Newsweekthe findings put scientific weight behind something many in his field had long suspected
“I’ve said for a long time that the gut is the most overlooked thing in modern medicine, so a study like this doesn’t surprise me, it just puts a mechanism under something a lot of us already suspected,” Brecka said
He noted that more than 95 percent of the body’s serotonin is produced mostly in the gut, not the brain
“What this adds is memory,” he added. “The vagus nerve is the line running between the two, and this research suggests it isn’t only carrying signals about hunger and fullness
“It’s carrying signals involved in forming a memory.”
…
Brecka said he was most struck by the finding that the brain responded to a food’s actual nutrient content, not its taste
“Your tongue and your biology are not measuring the same thing,” he said
He added that the long-term effects of an early poor diet were the most concerning part of the study
“What you eat over years isn’t just changing your weight, it’s changing the systems doing the signaling.”
He cautioned, however, that the research was conducted in rats, not humans, and does not show that childhood diet causes memory loss in adults, nor does it offer a treatment
What the Study Found
The research, led by Scott Kanoski, a professor of biological sciences at USC’s Dornsife College of Letters, Arts and Sciences, found that when rats ate nutritious food, neurons connected to the hippocampus—the brain region responsible for learning and memory—released higher levels of a chemical called acetylcholine, which helps the brain encode new experiences
When researchers severed communication along the vagus nerve, that boost in acetylcholine disappeared, and the rats performed worse on tests requiring them to remember where recent food was located
Notably, the rats that were fed a high-fat, high-sugar diet early in life showed weaker gut-to-brain signaling later on, even after switching to healthier food. Kanoski said the findings, despite being animal-based, could potentially point toward new research pathways and eventual therapies
“The disruption of acetylcholine signaling in the hippocampus is one of the earliest neurochemical changes in Alzheimer’s disease,” he said in a statement. “By revealing that this system is boosted by gut signaling from the vagus nerve, novel therapeutic targets could leverage this information to explore vagus nerve-based approaches, such as vagus nerve stimulation.”
Newsweek reached out to USC for further comment
Reference
Lauer, L. T., Kanoski, S. E. et al. (2026). The vagus nerve promotes memory in ratsNature Communications. https://doi.org/10.1038/s41467-026-73896-2
Contact Newsweek editors on this story: Kara Dolman and Sam Wilson
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