The Gut-Brain Axis – What Is It?

The human body is a fascinating thing. I have talked about the importance of listening to our hunger and satiety cues before, but how do we know we are full or hungry? Well, the gut-brain axis plays a big role. It is the communication system between cells in the GI tract and the brain. This connection can impact your mood believe it or not. The two have a relationship that is constantly being studied. Let’s discuss what we do know about the gut-brain axis and its impact on nutrition.




How Are They Connected?


There are a few different points of connection between the brain and gut.


Nervous System: Neurons are cells that make up the central nervous system, which connects the brain to various parts of the body, and the gut contains a lot of them. The vagus nerve is one of the larges nerves that connect the gut and brain, sending signals in both directions.


Neurotransmitters: These are hormones that are produced in the brain that control feelings and emotions. Serotonin is responsible for feeling happiness and controls circadian rhythm. Fun fact, many neurotransmitters are also produced in the gut via intestinal cells and microbes. A significant amount of serotonin is produced in the gut. Microbes in the gut produce gamma-aminobutyric acid which helps with feelings of fear and anxiety.


Short Chain Fatty Acids: Gut microbes make a lot of short chain fatty acids (SCFAs) like butyrate, propionate, and acetate. SCFA are made when the bacteria digest fiber. SCFA in the brain play the role of reducing appetite.