You might know cortisol as “The Stress Hormone” — and you’ve probably heard it shouldn’t get too high. That’s true. Chronically elevated cortisol has its fair share of negative effects on the body.
But while everyone is pointing fingers at high cortisol for causing health problems, there’s an opposite side of this coin that doesn’t get nearly enough attention. Most people don’t realize how important cortisol is when it comes to navigating chronic health challenges. And when it gets low, things can start to go wrong in ways you might not expect.
Cortisol (a glucocorticoid) is necessary for several major body processes to function normally. It’s integral to blood sugar regulation, proper immune function, blood pressure, and the metabolism of fat, protein, and carbohydrates. When cortisol levels drop too low, these systems may begin to struggle.
Here’s what I want to share with you today: cortisol isn’t the villain. In fact, it may be one of the most important hormones to pay attention to if you’re dealing with persistent digestive concerns or stubborn inflammatory responses that won’t seem to calm down.
Common Signs Associated with Low Cortisol
When cortisol levels run low, the body can send a wide range of signals. Some of the most commonly reported signs include:
- Persistent fatigue (even after rest)
- Difficulty recovering from exercise or illness
- Brain fog and poor concentration
- Low blood pressure or dizziness when standing
- Salt or sugar cravings
- Feeling overwhelmed by everyday stressors
- Aches and joint discomfort
- Digestive difficulties
In our experience working with people focused on gut health, fatigue is one of the most common concerns — right alongside digestive problems. The remaining signs tend to emerge as people explore their health picture in more detail.
Anyone navigating ongoing digestive concerns may also be dealing with persistent inflammatory responses. And when I was dealing with my own health challenges, I experienced many of these signs. At the time, they didn’t seem related. But after I began working with a practitioner on my cortisol levels, I noticed meaningful improvements across the board.
As I regained my health, I came to understand the critical role cortisol plays in a well-functioning body — and why a persistent inflammatory response is often the first signal worth paying attention to.
Inflammation: Your Body’s First Responder
Inflammation is a normal immune response in your body. It’s usually our friend. Think of it like the first responder arriving at the scene of an injury. Pain, swelling, redness, and warmth are all signs of the inflammatory process arriving at the site and supporting the body’s natural recovery.
After the initial response does its job, the body releases various signals — including cortisol — to calm the inflammatory process and return to baseline. Research has established that glucocorticoids like cortisol play a central role in modulating immune function and supporting the resolution of inflammatory responses.
But sometimes the inflammatory process doesn’t calm down… and that’s when things start to go wrong.
When the Campfire Becomes a Forest Fire
Think of it like starting a small campfire meant to keep you warm. Under normal conditions, the fire gets put out when it’s no longer needed. But imagine that campfire isn’t extinguished, and it grows into a forest fire burning 100,000 acres.
A prolonged inflammatory response occurs when the body’s normal immune signaling gets stuck in the “on” position. Research has linked these persistent inflammatory responses to changes in intestinal barrier function, cardiovascular health, joint function, and many other chronic health concerns.
Research published in a 2023 review in the International Journal of Molecular Sciences describes how chronic stress and cortisol dysregulation can promote sustained production of pro-inflammatory signaling molecules (cytokines) like IL-6 and TNF-α, while reducing the anti-inflammatory signaling that normally keeps the immune response in check.
It’s a vicious cycle: when the body’s inflammatory signals stay elevated, the demand on cortisol increases — and when cortisol can’t keep up, the inflammatory response may continue unchecked.
Cortisol: The Body’s Master Immune Regulator
Inflammation is just one part of our complex and amazing immune system, and cortisol plays a huge role in how well it functions.
Research on the effects of glucocorticoids like cortisol on gene expression has shown that they may upregulate and downregulate up to 2,000 genes involved in the regulation of the immune response. That’s not a typo — two thousand genes. Cortisol’s influence on the immune system is staggeringly broad.
A 2012 review published by the National Institutes of Health described the relationship this way: there is a bidirectional communication between the immune system and the HPA axis. Pro-inflammatory cytokines stimulate the HPA axis, and the resulting release of glucocorticoids provides negative feedback control of the immune response, helping to keep inflammation in check. Research has established that glucocorticoids exert an important modulatory role on the immune system, both calming and enhancing a variety of immune functions depending on what the body needs.
This is a critical concept: cortisol doesn’t just suppress the immune system — it helps regulate and balance it.
A 2025 review on chronic stress and autoimmunity confirmed that under normal conditions, cortisol restrains pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) while supporting anti-inflammatory cytokines (IL-10). However, chronic stress can lead to HPA axis dysregulation and what researchers call “glucocorticoid resistance” — where the body’s cells stop responding effectively to cortisol’s anti-inflammatory signals, even when cortisol levels may appear normal or elevated.
Low Cortisol and the Gut Connection
The mechanisms for naturally managing healthy inflammatory balance are complex, with many different processes playing a role. However, cortisol is one of the biggest players in calming inflammatory responses — and when it’s low, those responses may persist.
The bottom line: Cortisol helps put the inflammatory fire out. But it can’t do that job when levels are low.
A persistent inflammatory response may therefore be a signal worth exploring with a healthcare provider, particularly as it relates to cortisol status.
In our work with people focused on gut health, low cortisol has been one of the most common patterns we’ve observed across hundreds of assessments from individuals navigating digestive concerns. We’ve seen this pattern in people dealing with a wide range of gut challenges — from inflammatory bowel conditions to autoimmune-related digestive issues to general gut discomfort.
From our experience, cortisol appears to be vitally important for maintaining a healthy and fully functioning digestive tract, where balanced inflammatory signaling is essential.
Why Corticosteroid Medications Offer a Clue
This is also why corticosteroid medications (like prednisone and hydrocortisone) have long been prescribed by physicians to modulate immune responses in people with inflammatory bowel conditions. These medications are synthetic versions of cortisol — they work by supplementing what the body may not be producing sufficiently on its own.
If corticosteroid medications have ever provided you temporary relief, it may be worth discussing your cortisol status with your healthcare provider.
Emerging Research: The Gut Microbiome Talks Back to Cortisol
One of the most exciting areas of research involves the bidirectional relationship between the gut microbiome and the HPA axis. A 2015 study published in Psychopharmacology found that prebiotic supplementation significantly lowered the cortisol awakening response in healthy volunteers — suggesting that supporting the gut microbiome may influence the body’s stress hormone signaling.
Short-chain fatty acids (SCFAs), particularly butyrate, are metabolites produced when beneficial gut bacteria ferment dietary fiber. A 2020 randomized controlled trial found that colon-delivered SCFAs attenuated the cortisol response to psychosocial stress in healthy men, providing direct evidence that microbial metabolites can influence the HPA axis.
Research has also shown that SCFAs support gut barrier integrity, mucus production, and balanced inflammatory signaling — all of which are relevant when the body’s cortisol-driven regulation isn’t functioning optimally.
This is a two-way street: cortisol influences gut health, and gut health influences cortisol. Supporting one may help support the other.
Strategies That May Support Healthy Cortisol Function
If this article resonates with you, here are some strategies worth exploring — ideally alongside a qualified healthcare provider who can help evaluate your individual situation:
1. Consider Cortisol Testing
Saliva cortisol testing (often a 4-point test measuring cortisol at multiple times throughout the day) can provide insight into your daily cortisol rhythm. Unlike a single blood draw, this type of testing captures the natural rise and fall of cortisol over 24 hours. Talk with your practitioner about whether this is appropriate for you.
2. Prioritize Sleep and Circadian Rhythm
Cortisol follows a natural diurnal pattern — it rises in the morning to support wakefulness and energy, then gradually declines throughout the day. Disrupted sleep and irregular schedules can impair this rhythm. Consistent sleep and wake times, morning light exposure, and an evening wind-down routine all support healthy cortisol patterns.
3. Manage Stress Deliberately
Chronic stress is one of the primary drivers of cortisol dysregulation. Research has shown that positive social interaction may counteract the negative effects of stress on cortisol levels — in part through the release of oxytocin. Meditation, gentle movement, time in nature, and meaningful social connection all have research supporting their role in healthy stress management.
4. Support Your Gut Microbiome
Since the gut microbiome communicates directly with the HPA axis, supporting microbial diversity and SCFA production is relevant to cortisol health. A fiber-rich diet, fermented foods, and targeted probiotic or prebiotic supplementation may all play a role. Some people also choose to support their body’s cortisol balance with adaptogenic herbs and targeted nutritional formulas designed for stress resilience and adrenal support.
5. Address Gut Barrier Function
Cortisol dysregulation has been linked to changes in intestinal permeability. If you suspect your gut barrier may be compromised, addressing the root factors — including diet, stress, and targeted gut-supportive nutrients like L-glutamine and zinc carnosine — may support both gut health and a healthier stress response.
Frequently Asked Questions
Is cortisol always bad?
No. Cortisol is essential for life. It helps regulate blood sugar, supports immune function, maintains blood pressure, and plays a central role in managing the body’s inflammatory response. Problems arise when cortisol is chronically elevated or chronically low — both extremes can challenge the body’s ability to maintain balance.
What causes low cortisol?
Low cortisol can result from prolonged chronic stress (which may eventually deplete the body’s capacity to produce adequate cortisol), HPA axis dysregulation, or medical conditions like adrenal insufficiency (Addison’s disease). Only a qualified healthcare provider can properly evaluate and diagnose cortisol-related conditions.
How is cortisol connected to gut health?
Research has established a bidirectional relationship between cortisol and the gut. Cortisol influences gut barrier integrity, immune signaling in the digestive tract, and the composition of the gut microbiome. In turn, the gut microbiome produces metabolites (like short-chain fatty acids) that may influence HPA axis activity and cortisol patterns.
Can you test for low cortisol at home?
Salivary cortisol tests can be ordered through some healthcare providers and functional medicine practitioners. A 4-point saliva test (measuring cortisol at waking, noon, evening, and bedtime) provides the most useful picture of your daily cortisol rhythm. Blood and urine tests are also available. Always work with a practitioner to interpret results.
What’s the difference between “adrenal fatigue” and adrenal insufficiency?
Adrenal insufficiency (including Addison’s disease) is a medically recognized condition in which the adrenal glands cannot produce adequate cortisol. “Adrenal fatigue” is a term used in some practitioner communities to describe a state of HPA axis dysregulation where cortisol production may be suboptimal but does not meet the clinical threshold for adrenal insufficiency. If you suspect cortisol issues, work with a healthcare provider for proper evaluation.
What role do short-chain fatty acids play in cortisol regulation?
Short-chain fatty acids (SCFAs) — particularly butyrate — are produced when gut bacteria ferment dietary fiber. Emerging research suggests that SCFAs may influence HPA axis activity and support a balanced cortisol response. A 2020 clinical trial found that colon-delivered SCFAs reduced the cortisol response to stress in healthy men, pointing to a direct gut-to-brain connection in cortisol regulation.
Key Takeaways
- Cortisol is not the villain. It’s one of the body’s most important hormones for immune regulation, inflammatory balance, and digestive function.
- Low cortisol may be as problematic as high cortisol. Research suggests that insufficient cortisol can leave inflammatory responses unchecked, potentially contributing to chronic health concerns.
- Cortisol influences up to 2,000 genes involved in immune regulation — its effects are far-reaching.
- The gut and cortisol are deeply connected. Cortisol affects gut barrier function, and gut microbiome metabolites like butyrate influence HPA axis activity.
- If chronic inflammatory responses won’t resolve, cortisol status may be worth exploring with a qualified healthcare provider.
- Supporting gut health, sleep, stress management, and microbiome diversity may all contribute to healthier cortisol function.
Medical Disclaimer
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