Signals traveling from the gut to the brain help turn meals into lasting memories, but a steady junk-food diet could scramble that signal, according to new research from the University of Southern California (USC).
The research
Published in Nature Communications on July 29, 2026, the study led by Scott Kanoski, professor of biological sciences at USC Dornsife, examined how the vagus nerve—the main communication route between the gut and brain—influences memory. In experiments with rats, the team found that eating nutrient-rich foods increased the release of acetylcholine in the hippocampus, a brain region critical for learning and memory. This increase depended on messages traveling from the gut via the vagus nerve.
When researchers disrupted the vagus nerve, acetylcholine levels did not rise after eating, and rats performed worse on tests requiring them to remember food locations. The study also showed that the brain's memory system responded to nutritional content, not just sweetness: rats given sugar or fat showed strong memory activity, while those given low-calorie sweet liquids did not. Study first author Logan Lauer, a PhD student in Kanoski's lab, suggests the mechanism evolved to help animals recall where vital food sources are located.
However, chronic exposure to high-fat and high-sugar diets early in life weakened this gut-to-hippocampus communication, even after returning to a healthier diet, and impaired memory performance.
Why it matters
This research reveals a concrete link between what you eat and how your brain records food-related memories. For humans, it suggests that the nutritional value of meals—not just taste—may shape which experiences become memorable. It also highlights a potential risk of long-term unhealthy eating: it may subtly impair the brain's ability to form certain types of memories, possibly contributing to cognitive decline seen in obesity and poor nutrition.
What you can do
To keep your gut-brain memory pathway healthy, prioritize nutrient-dense foods rich in vitamins and healthy fats, like vegetables, fruits, and foods with omega-3s. Limiting ultra-processed, high-fat, high-sugar snacks may protect not just your body, but also your memory over time. Short-term, enjoying a balanced meal might help you remember where you learned something new.
Source: ScienceDaily Mind & Brain
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