SICK OF STRESS? HOW YOUR GUT MICROBIOME CHANGES UNDER PRESSURE

A collection of six petri dishes displays a variety of colorful bacterial cultures, showcasing differences in pigmentation and growth patterns.

Have you ever noticed yourself or others continuously getting sick during exam season? Have you ever uttered the words, “I’m gonna throw up,” or “I feel sick” before an important event? Or have you ever had trouble falling asleep due to stress from overthinking or daily worries?

If so, know that these occurrences aren’t coincidental. Emerging research is beginning to reveal a remarkable relationship between the microbes of the human gut and feelings of anxiety and stress.

WHAT IS STRESS

Stress is a natural reaction that the human body undergoes in response to life events, resulting in emotional, physical, or behavioral tension. Understanding the different types of stress and how they impact the body is crucial to maintaining both mental and physical health.

Acute stress is short-term, meaning it appears and resolves within a brief period. These experiences can be negative, such as getting into an argument, giving a presentation, or competing. They can also be positive, like starting a new job, planning a wedding, or moving somewhere new. Acute stress can cause mental fatigue and temporary anxiety while also sharpening judgment and productivity (Kohn et al., 2017).

Chronic stress, on the other hand, is long-term and typically develops gradually. It often stems from persistent stressors such as academic pressure, financial instability, or family issues, which can drastically influence mental and physical health. Prolonged exposure to stress can contribute to chronic illnesses, underscoring the importance of understanding how poor mental health directly affects physical well-being.

Illustrated depiction of various beneficial gut bacteria including Bifidobacterium, Lactobacillus, and Faecalibacterium prausnitzii, showcasing their distinctive shapes and structures.

WHAT IS THE MICROBIOME

The human microbiome is a diverse collection of microorganisms that live on and within the human body, including bacteria, viruses, and fungi, along with their associated genetics. These microbes play a crucial role in shaping human health.

The gut microbiome, in particular, has several key functions that regulate digestion, immune responses, brain function, and hormone activity (Madison et al., 2019). Because the microbiome is sensitive to changes in diet, sleep, behavior, and hormones, even minor fluctuations can alter the microbial composition of the gut.

THE COMPLEX RELATIONSHIP BETWEEN STRESS AND YOUR BODY

Anyone who has experienced anxiety or stress can attest to its physical symptoms: “a pit in the stomach,” a racing heart, heavy breathing, or nausea. These sensations originate in the brain and travel to the gut via a bidirectional communication network known as the gut-brain axis, which connects neural and hormonal pathways (Madison et al., 2019).

When these stress signals reach the gut, the body can misinterpret them as threats. The brain and gut then coordinate the release of cortisol, a hormone that primes the body’s “fight-or-flight” response. As stress accumulates, cortisol levels rise, which can disrupt the gut microbiome and damage the gut barrier.

Under normal conditions, short-chain fatty acids (SCFAs) help maintain gut barrier integrity by tightening junctions between intestinal cells and forming a protective mucus layer (Assimakopoulos et al., 2018). This barrier acts like a biological “scanner,” distinguishing harmful from beneficial bacteria. However, high cortisol levels weaken the barrier, increasing intestinal permeability (“leaky gut”) and allowing unwanted toxins or bacteria to enter the bloodstream.

This imbalance, known as dysbiosis, can cause digestive issues, mood changes, acne, and heightened inflammation due to a weakened immune system (Yoo et al., 2020). As a result, individuals under chronic stress may become more prone to illness, explaining why students often get sick during exams or people feel unwell in high-pressure situations. Over time, prolonged stress can contribute to cardiovascular, gastrointestinal, and neurological disorders (Rasheed, 2016).

CONCLUSION

While mild stress can sometimes enhance focus or motivation, consistent high levels of stress (and their negative effects on the gut microbiome) should not be overlooked. Everyday stress is unavoidable, and not every stressful episode will cause illness, but long-term imbalance between physical strain, mental fatigue, poor sleep, and poor diet can lead to serious health impacts.

Maintaining a balanced lifestyle through nutritious eating, adequate sleep, and stress-reducing activities can support both mental health and gut health. Remember, a healthy microbiome begins with a healthy mind. Prioritizing both mental and physical wellness is key to staying resilient under pressure.

Written by Amillia Nguyen and edited by Aldrin Gomes, PhD.

REFERENCES

Assimakopoulos, Stelios F., et al. “The Role of the Gut Barrier Function in Health and Disease.” Gastroenterology Research, vol. 11, no. 4, 1 Aug. 2018, pp. 261–263, www.ncbi.nlm.nih.gov/pmc/articles/PMC6089582/, https://pmc.ncbi.nlm.nih.gov/articles/PMC6089582/.

Kohn, Nils, et al. “Cognitive Benefit and Cost of Acute Stress Is Differentially Modulated by Individual Brain State.” Social Cognitive and Affective Neuroscience, vol. 12, no. 7, 11 Apr. 2017, pp. 1179–1187, https://pmc.ncbi.nlm.nih.gov/articles/PMC5490678/.

Madison, Annelise, and Janice K Kiecolt-Glaser. “Stress, Depression, Diet, and the Gut Microbiota: Human–Bacteria Interactions at the Core of Psychoneuroimmunology and Nutrition.” Current Opinion in Behavioral Sciences, vol. 28, no. 3, Aug. 2019, pp. 105–110, pmc.ncbi.nlm.nih.gov/articles/PMC7213601/, https://pmc.ncbi.nlm.nih.gov/articles/PMC7213601/.

Morys, Julia, et al. “Stress and the Gut-Brain Axis: An Inflammatory Perspective.” Frontiers in Molecular Neuroscience, vol. 17, 18 July 2024, https://pubmed.ncbi.nlm.nih.gov/39092201/.

Rasheed, Naila. “Prolonged Stress Leads to Serious Health Problems: Preventive Approaches.” International Journal of Health Sciences, vol. 10, no. 1, 2016, p. V, pmc.ncbi.nlm.nih.gov/articles/PMC4791152/. 

Yoo, Ji, et al. “Gut Microbiota and Immune System Interactions.” Microorganisms, vol. 8, no. 10, 15 Oct. 2020, p. 1587, https://pmc.ncbi.nlm.nih.gov/articles/PMC7602490/.