Stress and the stomach: The role of gut bacteria in stress response

For many university students, stress is a constant companion throughout the academic year. From looming deadlines to exams, the pressures of student life can feel overwhelming. Beyond the mental strain, stress can also disrupt gut health and weaken the immune system—a concept referred to as the gut-brain connection.

The brain and gut communicate through a system called the gut-brain axis, connecting the central nervous system to the enteric nervous system, governing the gastrointestinal tract.

Stress impacts the gut through a structure called Brunner’s glands. Located in the duodenum—the first part of the small intestine—these glands play a key role in maintaining gut health by producing mucus that protects the gut lining. When stress disrupts this system, it reduces mucus production, leading to an imbalance in gut bacteria and leaving the body more vulnerable to infections.

This connection means psychological stress can have physical consequences on the digestive system, often leading to digestive problems and compromised immune defenses.

Stress also causes the body to release cortisol, the primary stress hormone. While cortisol helps manage the body’s “fight or flight” response, it can negatively impact gut health when released continuously.

Cortisol disrupts the balance of gut microbiota—the collection of bacteria that live in the intestines and play a vital role in digestion and immune function. This disruption allows harmful bacteria to thrive while reducing the population of beneficial bacteria. Consequently, students may experience symptoms such as bloating, gas, or indigestion, which are all linked to this imbalance in gut health.

Stress also increases gut permeability, commonly referred to as “leaky gut.” When the gut becomes more permeable, bacteria and toxins can escape from the intestines into the bloodstream, triggering inflammation and weakening the immune response.

This makes students more susceptible to infections and illnesses, which can further exacerbate stress levels and create a vicious cycle. Stress disrupts the gut’s microbiome and increases permeability; the immune system becomes less effective at protecting the body from illnesses.

The immune system relies on the gut to function optimally. Around 70 per cent of the body’s immune cells reside in the gut, where they interact with gut bacteria to help defend against harmful pathogens.

For post-secondary students, this can mean more frequent colds, prolonged illnesses, and an increased risk of digestive conditions like irritable bowel syndrome (IBS).

“They [stress and health] both go hand-in-hand. Excessive stress will negatively affect your mental and physical health, then this makes you stressed. I couldn’t tell you the number of times I suddenly got sick before something stressful like midterms or exams. The timing couldn’t be worse,” Amaya Titus, Nurs ’26, said in an interview with The Journal.

While the mental health implications of stress are often the primary concern, it’s essential to recognize how stress-induced gut issues can affect overall well-being and academic performance.

Given the impact of stress on the brain-gut connection, it’s important for students to adopt

Some of these strategies include maintaining a balanced diet, regular exercise, healthy sleep schedule, breathing exercises and spending time with loved ones.