The Impact of Cortisol (Stress) on Gut Inflammation and Immunity

Discover how the chronic stress can alter the microbiota, the intestinal barrier, and the immune response.

Stress can affect your gut health

Stress is a part of everyday life and, in small doses, can even be adaptive. However, when maintained over time, our body can enter a state of sustained alertness that affects numerous physiological systems of relevance, such as the digestive system.

Scientific evidence shows that the gut is not only involved in the digestion and absorption of nutrients; también desempeña un papel fundamental en la regulación del sistema inmunitario y en el equilibrio inflamatorio del organismoIn fact, about 70% of the body's immune cells are associated with the intestinal lymphoid tissue, making the gut a true immune organ.

In this context, chronic stress and sustained cortisol elevation can profoundly alter the interaction between the microbiota, the intestinal barrier, and the immune system, favoring a pro-inflammatory environment that could impact digestive and systemic health.

Therefore, understanding how this interaction occurs and which strategies can help modulate it es clave para cuidar la salud digestiva from a comprehensive perspective.

What is cortisol?

El cortisol is an essential hormone for life produced in the cortex of the adrenal glands, located above the kidneys. Evolutionarily, it is the hormone responsible for allowing us to survive, as it prepares us to respond and flee from external threats.

Your key features in the body are:

• Stress response: It perpetuates the state of alertness by mobilizing nutrients to ensure that the body has quick energy reserves to react to danger.

• Metabolic action: It is a counter-regulatory hormone, which means it performs functions contrary to insulin, mobilizing energy for our responsiveness.

• Immune system and inflammation control: Act as a natural immunosuppressant. At appropriate levels, it is essential for modulating the inflammatory response and preventing it from spiraling out of control.

• Cardiovascular regulation: Help with maintain healthy blood pressure levels.

• Coagulation: Modulates clotting factors for prevent excessive bleeding against potential injuries.

How does your rhythm work? 

Cortisol is a hormone linked to the response to the stress and works by following a circadian rhythm normal, released in pulses throughout the day (with main peaks around 7-8 a.m., 11-12 p.m., and 4 p.m.) and decreasing at night.

Health problems (fatigue, immunosuppression, water retention) do not arise from having cortisol, but rather when this normal rhythm is lost pulse-by-pulse due to chronic stress, leaving the hormone permanently elevated and dysregulated.

Stress and the digestive system: a bidirectional connection

The relationship between the brain and the gut is much closer than traditionally thought. Both organs communicate through the well-known gut-brain axis, a complex network that integrates the central nervous system, the enteric nervous system, the immune system, the gut microbiota, and the endocrine system. One of the primary mediators of this communication is the hypothalamic-pituitary-adrenal axis, responsible for the release of cortisol in response to stress.

Under normal conditions, this signaling allows the body to adapt. However, when stress becomes chronic, the persistent activation of the HPA axis can disrupt different digestive processes.

Various studies have shown that it can influence intestinal motility, gastric acid secretion, visceral sensitivity, and the composition of the microbiota intestinal. These alterations help explain why many people experience digestive symptoms such as bloating, changes in bowel habits, or digestive discomfort in stressful moments.

Additionally, the enteric nervous system, often known as the “second brain,” responds directly to signals from the central nervous system; in turn, the microbiota also participates in this communication by producing metabolites and neurotransmitters that influence brain function and stress regulation.

This explains why psychological stress can affect digestive function, but also why digestive disturbances can impact mood and the stress response.

What happens if you have high cortisol levels?

Impact of cortisol on the microbiota, intestinal barrier, and immunity

We know that el sustained increase in cortisol could lead to significant changes in the gut ecosystem. Experimental models and human studies suggest that stress could reduce bacterial diversity and promote changes in the presence of certain microbial groups, altering the balance of the intestinal ecosystem.

microbiota plays key roles in digestion, in the production of metabolites such as short-chain fatty acids and in the regulation of the immune response. Therefore, when this balance is disrupted, these functions can also be affected.

Another important aspect is the effect of stress on the intestinal barrier. We know that the The intestinal epithelium acts as a selective barrier that allows for the absorption of nutrients, while limiting the passage of microorganisms or potentially harmful compounds. However, prolonged activation of the stress axis could modify the integrity of this barrier.

Some studies have observed that cortisol and other stress mediators can alter proteins that regulate the tight junctions between intestinal cells, promoting a increased intestinal permeability.

Symptoms of high cortisol levels

When cortisol remains high for a long time, it doesn't always manifest in just one way. In many people, the symptoms appear progressively and they can be confused with the pace of everyday life.

Some signs that may be associated with sustained stress and prolonged elevated cortisol levels are:

Metabolic and body composition changes

Fat is redistributed toward the abdomen and face (manifesting as a "moon face"), while the limbs remain thin. It induces insulin resistance, hyperglycemia, increased triglycerides, and elevated cholesterol. Additionally, it has a catabolic effect that causes muscle wasting and bone loss, increasing the risk of osteoporosis.

Skin conditions

It causes skin fragility, making it easier for bruises to appear even with minimal trauma. It produces wine-red stretch marks, especially on the abdomen, arms, and armpits, because it thins the blood vessels. Secondary to insulin resistance, darkening of the neck and armpits may occur, as well as excess body hair.

Cardiovascular and renal effects

Excess cortisol binds to aldosterone hormone receptors, inducing excessive sodium and water retention in the kidneys, which results in fluid retention and high blood pressure. Additionally, it increases magnesium loss through urine.

Immunosuppression

It decreases the response of lymphocytes and eosinophils, creating a state of immunosuppression that increases the predisposition to contracting infections.

Suppression of the reproductive and thyroid axis

At the brain level, elevated cortisol stimulates the CRH hormone, which inhibits GnRH; this reduces the secretion of FSH and LH, blocking follicular development and causing a lack of ovulation and amenorrhea. It also decreases thyroid gland function, slowing down the metabolism.

Neurological and mood disorders

The loss of the physiological nocturnal decline in cortisol prevents relaxation and proper rest, causing insomnia, chronic fatigue, nervousness, apathy, and depressive symptoms.

Consequences of elevated cortisol on the microbiota, the intestinal barrier, and immunity

When the intestinal barrier is compromised, certain bacterial components or proinflammatory molecules can come into contact with the intestinal mucosal immune system, activating a local response with release of inflammatory mediators.

This process could contribute to a state of low-grade inflammation, with potential long-term repercussions for digestive, metabolic, and immune health.7

In other words, chronic stress can not only make the gut "feel worse," but also promote a less resilient physiological environment. That is why, talking about high cortisol levels it's not just about talking about stress: also es talking about microbiota, intestinal permeability, and immunity.

How to naturally lower cortisol and protect gut health

Although stress is an inevitable part of life, there are various science-backed strategies that can help protect gut health and promote a more balanced inflammatory response.

Foods rich in fiber and bioactive compounds

Diet and nutrition plays an especially relevant role. Various studies have shown that dietary patterns rich in plant-based foods, fiber, and bioactive compounds promote a more diverse and resilient microbiota.

In this sense, the Mediterranean diet pattern has been associated with a higher fatty acid production short-chain by the gut microbiota, which contributes to maintaining the integrity of the intestinal barrier and helps modulate inflammation.

The fiber health food store, found in fruits, vegetables, legumes, nuts, and whole grains, acts as substrate for the growth of beneficial bacteria. Its fermentation leads to the production of compounds such as butyrate, which plays a role key to the health of intestinal epithelial cells and the regulation of the immune response.

Additionally, many plant-based foods contain polyphenols, compounds with antioxidant activity that also interact with the gut microbiota. Fruits such as the blueberries, raspberries, cocoa, green tea, or olive oil extra virgin are examples of foods rich in these compounds.

Omega-3 and inflammatory balance

On the other hand, certain omega-3 fatty acids, present in oily fish, walnuts, flaxseeds, and chia seeds, they have been associated with modulating effects on inflammation and could contribute to rebalancing the immune response in different tissues, including the gut.

Sleep and circadian rhythm

Beyond nutrition, other factors such as sleep also influence the balance of the gut-brain axis. Getting a good night's sleep plays a fundamental role in hormonal regulation and stress modulation. Insufficient or irregular sleep could disrupt the circadian rhythm of cortisol, indirectly affecting metabolic and immune balance.

Regular physical activity

Regular physical activity also has partnered with benefits for the gut microbiota and the regulation of systemic inflammation. Engaging in moderate and consistent exercise seems to promote greater microbial diversity and improve the body's resilience to stress.8

Stress management strategies

Finally, different stress management strategies such as mindful breathing, meditation, or yoga have shown positive effects on the regulation of the hypothalamic-pituitary-adrenal axis and on inflammatory markers.

These strategies do not replace medical treatment when a specific pathology exists, but they can be part of a comprehensive approach aimed at promoting the body's physiological balance.

How IVB can help you

Taking care of your gut also involves learn to manage the stress that comes with daily lifeAt IVB, we understand digestive health from a holistic perspective, where microbiota, inflammation, immunity, and lifestyle are deeply interconnected.

That is why, in addition to proper nutrition and habits that promote stress resilience, it may make sense to rely on nutritional solutions that help care for the intestinal environment and maintain balance of the organism during peak demand periods.

• Stress OFF
  It is specifically designed for help the body manage daily stress. Combine adaptogens like the reishi, eleuthero, and schisandra. In particular, schisandra helps modulate the hypothalamic-pituitary-adrenal axis, promoting normalization of circadian cortisol secretion and preventing chronic spikes that drain energy.

• Total Magnesium
  Chronic stress and increased cortisol levels lead to an accelerated loss of magnesium through urine, creating a vicious cycle of more stress and less magnesium. Magnesium is vital because regulates the secretion of the ACTH hormone

 

References

1. Camilleri M, et al. Intestinal barrier function in health and gastrointestinal disease. Neurogastroenterol Motil. 2012 Jun; 24(6):503-12.

2. Bischoff SC, et al. Intestinal permeability--a new target for disease prevention and therapy. BMC Gastroenterol. 2014 Nov 18;14:189.

3. Camilleri M. Human Intestinal Barrier: Effects of Stressors, Diet, Prebiotics, and Probiotics. Clin Transl Gastroenterol. 2021 Jan 25;12(1):e00308.

4. Macura B, et al. Intestinal permeability disturbances: causes, diseases and therapy. Clin Exp Med 24, 232 (2024).

5. Carmine S, et al. Implication of Intestinal Barrier Dysfunction in Gut Dysbiosis and Diseases. Biomedicines. 2022 Jan; 10(2), 289.

6. Matar A, et al. Intestinal Barrier Impairment, Preservation, and Repair: An Update. Nutrients. 2024;16(20):3494.

7. Sun L, Zhang B. The digestive system and autoimmunity. BMC Immunol. 2023 Oct 4;24(1):36.

8. Dmytriv TR, et al. Intestinal barrier permeability: the influence of gut microbiota, nutrition, and exercise. Front Physiol. 2024 Jul 8;15:1380713.

9. Rose EC, et al. Probiotics, Prebiotics and Epithelial Tight Junctions: A Promising Approach to Modulate Intestinal Barrier Function. Int J Mol Sci. 2021 Jun 23;22(13):6729.

10. Slavin J. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013 Apr 22;5(4):1417-35.

11. Aya V, et al. Association between physical activity and changes in intestinal microbiota composition: A systematic review. PLoS One. 2021 Feb 25;16(2).