The gut-brain connection, also known as the gut-brain axis, refers to the communication between the digestive system and the brain. Anyone who has ever felt butterflies in their stomach or gotten nauseous at the thought of riding a rollercoaster needs no convincing that emotions and physical sensations are inextricably linked.
This connection has been of particular interest to the medical community and public at large in recent years. New studies show that “your brain affects your gut health, and your gut health may even affect your brain health.”1
Exactly how are the brain and the digestive system linked? Scientists are still learning about this relationship, but we do know that the gut and the brain are connected both physically (through the nervous system) and biochemically. The latter has a lot to do with the chemicals created in the process of digestion and the messages those chemicals send to the brain about how the body should react. For example, neurotransmitters, the chemicals that regulate emotions, are produced by gut cells and microbes in the digestive tract.2 Serotonin, which is responsible for feelings of happiness is produced in no small quantity in the gut!2
Gut microbes also produce SCFAs or short-chain fatty acids. These chemicals are a product of your gut’s “friendly” bacteria, or probiotics. Several studies have shown that certain probiotics can help reduce symptoms of anxiety, stress, and depression. These sorts of probiotics—those known to have a strong connection to the brain—are often referred to as “psychobiotics.”
You may have heard about the benefits of probiotics. They’re found in fermented foods like yogurt and can have a positive effect on digestive health, and, as we just discussed, brain health. However, equally important are prebiotics, which help feed probiotics in the gut. In addition to supporting a healthy gut environment where psychobiotics can thrive, prebiotics themselves have been shown to help reduce the amount of cortisol (the stress hormone) in the body.3
Not only does the food you put in your body affect your digestive system, but it also contributes to how other systems in the body function and communicate with one another. By this token, a healthy, balanced diet is not a discrete part of wellness, but rather part of a family of systems that comprise the microbiome—that comprise you!
1 Robertson R. The Gut-Brain Connection: How it Works and the Role of Nutrition. Healthline. Published June 27, 2018. https://www.healthline.com/nutrition/gut-brain-connection. Accessed September 17, 2019.
2 Yano JM, Yu K, Donaldson GP, et al. Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis. Cell. 2015 Apr 9. 161(2); 264-276. doi: 10.1016/j.cell.2015.02.047.
3 Schmidt K, Cowen PJ, Harmer CJ, et al. Prebiotic intake reduces the waking cortisol response and alters emotional bias in healthy volunteer. Psychopharmacology. 2014 Dec 3. 2015;232(10):1793-1801. doi:10.1007/s00213-014-3810-0.