Gut-brain axis The gut and brain communicate through the gut-brain axis, connecting physically and biochemically. They can influence each other’s health. The Vagus Nerve and the Nervous System The vagus nerve is a major link between the gut and brain, transmitting signals both ways. The gut has 500 million neurons connected to the brain through this system. Stress can inhibit vagus nerve signals, leading to gastrointestinal issues, as seen in studies with animals and humans.