Why you never forget a great meal: Gut instinct was the ‘GPS of early man’

While many of us struggle to remember names or addresses, remembering a great meal is far more simple.

Most people can remember an incredible amount of detail about their favourite burgers, cakes or  meals.

Now, scientists believe they know why – and say food and memory is far more closely linked than thought.

A new study by the University of Southern California found the body’s longest nerve, the vagus nerve, is the link between what scientists have referred to as the ‘two brains’ – the one in your head and the other in your gastrointestinal tract.

Researchers say it helps explain why food has such a prominent place in our memory.

They say it was critical to being able to find hunting grounds or fertile growing areas. 

‘When animals find and eat a meal, for instance, the vagus nerve is activated and this global positioning system is engaged,’ said Scott Kanoski, an assistant professor of biological sciences at USC Dornsife, who led the research.

‘It would be advantageous for an animal to remember their external environment so that they could have food again.’ 

The scientists wrote in the June 5th study in Nature Communications that their findings may raise an important and timely medical question that merits further exploration: Could bariatric surgeries or other therapies that block gut-to-brain signaling affect memory? 

Traditionally the vagus nerve is key for telling you to stop eating, transmitting biochemical signals from the stomach to the most primitive part of the brain, the brainstem.

In the new animal study, researchers found it does far more than just stopping us eating when we are full. 

Researchers say the link was critical to being able to find hunting grounds or fertile growing areas again

This ‘gut-brain axis’ may help you remember where you ate by directing signals to another part of the brain, the hippocampus, the memory center.

To examine this gut-brain connection, the research team conducted the study on rats. 

They saw that rats with their gut-brain vagus nerve pathway disconnected could not remember information about their environment.

‘We saw impairments in hippocampal-dependent memory when we cut off the communication between the gut and the brain,’ said lead author Andrea Suarez, a PhD candidate in biological sciences. 

‘These memory deficits were coupled with harmful neurobiological outcomes in the hippocampus.’

Specifically, the disconnected pathway affected markers in the brain that are key for the growth of new neural connections and new brain cells.

However, it did not appear to affect the rats’ anxiety levels or their weight, the scientists noted.