Gut Feeling

Our emotions influence our everyday actions and decisions, shaping how we interact with our environment. Traditionally, mental health has been understood as being influenced by life experiences and brain chemistry. However, recent scientific discoveries point to a “second brain,” the gut, which may play a significant role in how we feel. Our gut hosts trillions of microbes throughout the digestive tract, collectively known as the gut microbiota. These microorganisms play an important role in the gut-brain relationship.

The gut is part of the gastrointestinal system, which includes the stomach, colon, and intestines. Its functions include absorbing nutrients and removing waste from the body. The gut contains a variety of microorganisms, including species of yeast, bacteria, parasites, and fungi. Every person has a unique gut microbiome with different levels and types of these microorganisms. Many factors, such as genetics, environment, and antibiotic use, can affect it. For example, regular antibiotic use can eliminate certain groups of bacteria and alter the overall composition of the gut.

Gut-brain communication is a system that passes signals between the digestive system and the central nervous system. This is known as the gut-brain axis. One of the main pathways involved is the vagus nerve, which acts as a channel for messages between the gut and brain. Gut microbes can produce chemicals that influence communication between these systems. While the brain sends motor and regulatory signals to the gut, the gut provides sensory and chemical signals, whether it is signaling hunger or a change in mood.

The vagus nerve acts as a conduit for messages that can travel from the enteric nervous system throughout the gastrointestinal tract. This subdivision of the nervous system is sometimes described as a “second brain” because it can manage many aspects of digestion independently of the brain. Although it does not function in complete isolation, the enteric nervous system is constantly sending information through pathways connected to the vagus nerve. This communication may help explain the connection between gut activity and what we experience as “gut feelings.”

While this has been a topic of discussion for many years, newer scientific evidence has provided more insight into how the gut may influence mental health. Much of this research has involved comparing individuals with mental health disorders with healthy individuals. Clinical associations have been found between mental health conditions and dysbiosis, an imbalance in the gut microbiome. Dysbiosis can involve having too much or too little of certain bacterial strains.

Research has also suggested that people with certain mental health disorders may have lower levels of Lactobacillus and Bifidobacterium, which are groups of bacteria that may play a role in producing or regulating compounds involved in mood and brain function. Surprisingly, 90–95% of the body’s serotonin is produced in the gastrointestinal tract. Serotonin is involved in mood regulation, among many other functions. This connection may help explain why functional bowel issues and periods of high anxiety or depression can sometimes occur together. According to the research cited here, around 30–40% of the global population experiencing functional bowel issues may also experience anxiety or depression.

Despite this concerning connection, gut health can be supported through a variety of habits. Focusing on a whole-food-rich diet can provide important micronutrients, while increasing fiber intake can support regular digestion. Consuming prebiotics and probiotics can introduce or support microorganisms in the gut and aid the functions of existing microbes.

Finally, antibiotics should be used only when they are needed and prescribed appropriately. They are not effective against viral illnesses such as the common cold or flu. Overuse or inappropriate use of antibiotics can contribute to antibiotic resistance. Antibiotics can also affect beneficial bacteria alongside the bacteria they are intended to target.

Ultimately, the relationship between the gut and the brain is a reminder that different systems in our bodies do not operate independently. The gut and brain are constantly communicating, and understanding that relationship could help researchers better understand both physical and mental health. A healthy gut may be one piece of a healthier you.

Reference List

Ataei, P., Kalantari, H., Bodnar, T. S., and Turner, R. J. (2026). “The Gut–Brain Connection: Microbes’ Influence on Mental Health and Psychological Disorders.” Frontiers in Microbiomes, vol. 4. doi:10.3389/frmbi.2025.1701608.

Cleveland Clinic. (2023a). “Gut Microbiome.” Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/body/25201-gut-microbiome. Accessed 2 Oct. 2026.

Cleveland Clinic. (2023b). “The Gut-Brain Connection.” Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/body/the-gut-brain-connection. Accessed 28 Sept. 2026.

Harvard Health Publishing. (2023). “The Gut-Brain Connection.” Harvard Health. Available at: https://www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection. Accessed 5 Oct. 2026.

Johns Hopkins Medicine. (2019). “The Brain-Gut Connection.” Johns Hopkins Medicine. Available at: https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection. Accessed 1 Oct. 2026.

Ke, S., Guimond, A.-J., Tworoger, S. S., Huang, T., Chan, A. T., Liu, Y.-Y., and Kubzansky, L. D. (2023). “Gut Feelings: Associations of Emotions and Emotion Regulation with the Gut Microbiome in Women.” Psychological Medicine, vol. 53, no. 15, pp. 1–10. doi:10.1017/S0033291723000612.

Nikel, K., Stojko, M., Smolarczyk, J., and Piegza, M. (2025). “The Impact of Gut Microbiota on the Development of Anxiety Symptoms—A Narrative Review.” Nutrients, vol. 17, no. 6, p. 933. doi:10.3390/nu17060933.

Tompa, R. (2025). “What’s the Deal with the Gut-Brain Connection?” Stanford Medicine News Center. Available at: https://med.stanford.edu/news/insights/2025/03/gut-brain-connection-long-covid-anxiety-parkinsons.html. Accessed 28 Sept. 2026.