The intestine is not only a tube for digesting food and absorbing nutrients; Recent research reveals a complex neural and hormonal network linking the digestive system to the brain. In the latest chapter of this relationship, an experimental study indicates that signals coming from the intestines may help the brain form memories related to food and where it was obtained.
When we remember a meal we ate in a restaurant, or recall the place of food we loved, we may think that the senses and the brain are the only ones responsible for forming this memory, as the shape, smell, taste, and sounds surrounding it are all information that the senses pick up and the brain processes.
But a recent study says that the formation of these memories may also depend on messages arriving from within the body itself. After food enters the digestive system, the intestine sends nervous information to the brain telling it that what was eaten contains nutrients that are worth keeping the associated experience in memory.
The study was published in June 2026 in the journal Nature Communications, and was conducted by researchers from the University of Southern California and other scientific institutions. In experiments conducted on male rats, researchers found that consuming nutrients activates a neural pathway that begins from the digestive system, passes through the vagus nerve, and ends in an area of the brain that plays a central role in learning and memory.
A highway between the intestine and the brain
The vagus nerve is one of the most important means of communication between the viscera and the brain. It extends from the brainstem to a number of organs in the body, including the heart, lungs, stomach, and intestines. Its role is not limited to sending commands from the brain to the organs, but in the opposite direction, it transmits sensory information from within the body to the brain.
These signals tell the nervous system, for example, about the presence of food in the digestive system, how much the stomach expands, and the nature of some nutrients that have reached the intestine.
The role of the vagus nerve in regulating digestion, appetite, and feelings of satiety has long been known. However, the new study indicates that its effect may extend to higher cognitive functions, including the formation of memory associated with the eating event.
The researchers focused on a brain area called the hippocampus, which is an essential structure in forming memories, learning, determining locations, and navigating a place. They also studied a group of neurons located in an area called the medial septum, which send their extensions to the hippocampus.
Acetylcholine…a message to record the experiment
Experiments showed that eating food by rats led to an increased secretion of a chemical called “acetylcholine” within the dorsal hippocampus. Acetylcholine is a neurotransmitter that nerve cells use to communicate with each other, and it has an important role in attention, learning, neuroplasticity, and the formation of new memories. Its rise during eating can be likened to a signal that helps the brain pay attention to the current event and record information related to it.
The increase in acetylcholine was not limited to the period of eating, but rather continued for some time after the end of the meal, which means that signals coming from the digestive system may continue to influence memory consolidation processes after eating. The researchers knew that it is the vagus nerve that transmits this message after they cut the vagus nerve connection under the diaphragm.
The normal increase in acetylcholine within the hippocampus disappeared. Something similar happened when they removed the group of cholinergic cells in the medial septum, which are cells that produce acetylcholine and are connected to the hippocampus. These results indicate the existence of a communication chain that begins with nutrient signals in the digestive system, then travels through the vagus nerve to the brain, before activating cholinergic cells and increasing the secretion of acetylcholine in the hippocampus.
Does the brain remember taste or nutritional value?
The researchers also wanted to know whether this brain activity resulted from the delicious taste of the food, or from the presence of real nutrients and energy reaching the digestive system.
The results showed that consuming fats or sugars led to a clear response associated with memory, while liquids that tasted sweet but were low in calories or free of them did not produce the same neural response.
This means that the brain was not responding to the sweet taste alone, but rather to the information that comes after the nutrients reach the digestive system. The mouth tells the brain what food tastes like, while the intestines seem to tell it its actual nutritional value. From an evolutionary perspective, this mechanism may have a clear benefit. An animal that remembers the place where it found food rich in energy or nutrients has a greater chance of returning to that place and finding food again. Thus, remembering the location of food is not just a passing detail, but rather a behavior that helps survival.
Meal location memory test
The researchers not only measured chemical activity in the brain, but also subjected the rats to a behavioral test to measure their ability to remember the location of food.
The animals ate food inside a hidden tunnel in a maze, and were then tested a short time later to see if they could remember where they found the meal.
Rats whose vagus nerve was disabled, or whose acetylcholine-producing cells connected to the hippocampus were removed, performed worse at remembering the location of food.
This enhances the possibility that the discovered neural pathway does not only accompany eating, but actually plays a functional role in forming memory associated with the location of the meal.
The paradox of fats and sugars
One finding may seem puzzling at first glance: Acute intake of fats and sugars led to strong activity in the memory-related pathway, but chronic exposure to a diet rich in them led to the opposite result.
Rats who were fed a Western diet high in fat and sugar early in their lives later showed impaired communication between the intestine and the hippocampus, decreased acetylcholine response after meals, and poorer performance on a test of remembering the location of food. Some of these changes persisted even after the animals were returned to a healthy diet in adulthood.
There is not necessarily a contradiction between the two results, as the acute response to a particular nutrient differs from the effect of chronic exposure to an unbalanced dietary pattern. Nutrients may activate the neural pathway after a single meal, while a diet high in fats and sugars over the long term can impair the sensitivity of this pathway or alter its function.
What does the satiety hormone have to do with it?
Scientists also investigated the role of an intestinal hormone called cholecystokinin, which is secreted when nutrients, especially fats and proteins, reach the small intestine. This hormone contributes to regulating digestion and sending satiety signals via the vagus nerve.
In the study, its administration increased acetylcholine activity in the hippocampus, but this response disappeared when the vagus nerve was cut or cholinergic cells in the medial septum were removed.
This finding suggests that the hormones we typically associate with digestion and satiety may also influence, indirectly, learning and memory systems.
Do the results apply to humans?
Here you must act with caution. The study was conducted on male rats, and some of the experiments used surgical and neurological interventions that cannot be applied in the same way to humans. The tests also focused on recent spatial memory related to the location of food, and did not test all types of memory.
Therefore, the results do not prove that eating a specific food will strengthen a person’s memory, nor do they mean that memory weakness is necessarily caused by a defect in the intestines or the vagus nerve. It does not justify the use of nutritional supplements or commercial products that claim to activate the gut-brain axis.
Nor should the potential impact of the Western diet be reduced to a single pathway. Diets rich in fats and sugars may affect the brain through multiple mechanisms, including metabolic disturbance, inflammation, altered hormonal signals and the gut microbiome, in addition to a possible effect on the vagus nerve.
The importance of the study is mainly to identify a potential biological mechanism that can be tested in the future in humans, and not to provide a ready-made treatment recommendation.
A new window to understanding memory
The results also draw attention to acetylcholine, because disruption of cholinergic signaling in the hippocampus is one of the neurological changes observed in some neurodegenerative diseases, including Alzheimer’s disease. But the link between the study and Alzheimer’s treatment is still hypothetical and early.
Researchers will need to know whether the same pathway exists in humans, the extent to which it is affected by age, diet, obesity and diabetes, and whether improving communication between the gut and the brain can actually protect cognitive functions.
The study thus adds a new piece to a widening picture: Memory is not a process that occurs in isolation from the rest of the body. The brain integrates information coming from the outside world, such as sight, smell, and taste, with signals coming from inside the body, such as hunger, satiety, and the arrival of nutrients to the digestive system.
The gut may not be where memories are stored, but it may help the brain decide which food experiences are worth recording. The transition from these experimental results to human health still requires many studies, but the scientific message has become clearer: the relationship between food and memory does not begin and end in the brain, but may also pass through the intestines and the vagus nerve.