The Gut-Brain Axis
- lnfiabane
- Feb 28, 2025
- 2 min read
Updated: Mar 12, 2025
The Gut-Brain Axis (GBA), also known as the Gut-Brain Connection, refers to the bidirectional communication between the central nervous system and the enteric nervous system that connects cognitive and digestive behavior. The enteric nervous system has been described as a second brain in the gastrointestinal tract that regulates digestion. Not only is the GBA responsible for the butterflies in your stomach, but it may also be the underlying factor for some psychiatric, gastrointestinal and neurological conditions such as Major Depressive Disorder, Irritable Bowel Syndrome and Parkinson’s Disease.
So how do the gut and brain communicate? Scientists have identified a number of physiological components that contribute to their relationship.
Vagus Nerve
There are 500 million neurons that inhabit the gastrointestinal tract. However, compared to other sensory organs like the tongue and nose, our understanding of the gut is primitive. The vagus nerve is the major pathway that connects the brain to the gut. It runs from the brain, through the lungs, heart, spleen, liver, kidneys and down to the intestines. Interestingly, if severed, the intestines can still function without direction from the central nervous system.
Neuropod Cells
According to the research of Duke neuroscientist Dr. Diego Bohorquez, specialized enteroendocrine cells in the lining of the intestinal wall, called neuropod cells, communicate with vagal neurons upon stimulation by molecules in the gut, such as the nutrients present in food particles, bacteria or pathogens. This communication can occur within seconds. In a 2018 study Bohorquez and his fellow researchers explain, “Sensory cues that stimulate the gut could potentially be manipulated to influence specific brain functions and behavior, including those linked to food choices.” This has great implications for future application in the management of obesity.
Gut Microbiome
As described in our post about the microbiome, it is made up of trillions of bacteria in the gut. The microbiome weighs more than the brain – over 4 pounds! Bacterial strains in the gut produce neurotransmitters and short chain fatty acids that stimulate the nervous system. Specific types of bacteria have been found to enhance memory and regulate stress. The study of psychobiotics, specific bacteria that have mental health benefits when ingested, and the practice of fecal transplants has emerged in recent years.
Gastrointestinal Hormones
Neuroendocrine signaling occurs when bacteria in the gut trigger enteroendocrine cells in the lining of the intestinal wall to release neuropeptides like cholecystokinin which is a well-studied satiety hormone. Additionally, more than ninety percent of serotonin is made in the gut. Serotonin plays an important role in regulating mood.
Final Thoughts
Therefore, it may be that your diet might affect your mood and your mood might affect your digestion. “We still don’t quite know how nutritional microbes control us yet, but food is at the center of who we are,” explained Dr. Bohorquez in an interview with NC State University. The interaction of vagal neurons, neuropods, gut bacteria and neuropeptide hormones contributes to brain activity and gut health. Scientists are currently investigating ways to promote healthy communication between the gut and the brain, as well as identify what hinders their relationship. This research contributes to a growing body of evidence that suggests that the GBA is a promising target for medical therapies in the treatment of a number of disorders.
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