The digestive system and the central nervous system are connected by various nerve fibers or neurons. The connection between the digestive system and the human brain is a two-way process. Improper functioning of the digestive system can lead to sending incorrect messages to the brain. Also, dysfunction in the brain can lead to digestive problems. The digestive system contains many nerve neurons, so the digestive system is highly susceptible to stress. As you have probably experienced, the effect of anxiety on your digestive system is no less than that of unhealthy nutrition, which is why the gut is also called the second brain.