Fullscript Academy

The gut-brain axis is a bidirectional communication network that highlights the importance of gut health in regulating the body’s stress response and adrenal function. Keep reading to learn about the role of the microbiome and how to approach laboratory analysis comprehensively to support your patients.

How gut health impacts the stress response

The gut microbiome consists of trillions of microorganisms that play a crucial role in endocrine functions, including the adrenal glands. (Rusch 2023) The adrenal glands produce hormones such as cortisol, which is vital for the stress response.

A healthy gut microbiome supports the adrenal glands by regulating the hypothalamic-pituitary-adrenal (HPA) axis, the central stress response system. (Rusch 2023) Beneficial gut bacteria produce short-chain fatty acids (SCFAs) like butyrate, which have anti-inflammatory properties and help maintain the integrity of the gut lining. (Shin 2023) A robust gut lining prevents endotoxins from entering the bloodstream and triggering systemic inflammation, which can dysregulate the HPA axis and impair adrenal function. (Mohammad 2021)(Ahmad 2021)

However, an imbalance in the gut microbiome, known as dysbiosis, can disrupt the HPA axis. Dysbiosis often leads to increased intestinal permeability, commonly referred to as "leaky gut." This condition allows harmful substances to pass into the bloodstream, causing chronic low-grade inflammation and placing additional stress on the adrenal glands. (Aleman 2023) Over time, chronic stress and inflammation can lead to adrenal fatigue or dysfunction, impairing the body's ability to respond effectively to stress. (Hannibal 2014)

Both weight gain and weight loss can be associated with cortisol level imbalances. 

The role of the microbiome on cortisol levels

Cortisol, the primary stress hormone produced by the adrenal glands, plays a critical role in regulating metabolism, the immune response, and inflammation. The gut microbiome influences cortisol production through various mechanisms. For instance, certain gut bacteria can produce neurotransmitters like gamma-aminobutyric acid (GABA) and serotonin, which modulate the HPA axis and cortisol secretion. (Rusch 2023)

Dysbiosis can lead to altered cortisol levels, either by increasing or decreasing its production. (Rusch 2023) Over time, chronic stress and elevated cortisol levels are associated with various health issues, including hypertension, insulin resistance, weight gain, heart attack, stroke, diabetes, and neurological problems like memory loss and mood changes. (NIDDK 2023) On the other hand, decreased cortisol levels can cause weight loss, chronic fatigue, muscle weakness, and loss of appetite. (NIDDK 2022)

The role of the microbiome in inflammation

Inflammation is another critical aspect influenced by the microbiome. A healthy gut microbiome produces anti-inflammatory metabolites, helping to regulate the body's inflammatory response. Dysbiosis disrupts this balance, leading to increased production of pro-inflammatory cytokines. (CDC 2024) Chronic inflammation can damage the body’s glucocorticoid receptor, increasing cortisol dysfunction. (Hannibal 2014)

Signs of microbiome imbalance affecting adrenal health

Recognizing the signs of microbiome imbalance is essential for identifying potential impacts on adrenal health.

Anxiety and mood disorders

The gut-brain axis plays a crucial role in mental health. Dysbiosis can affect neurotransmitter production, leading to symptoms of anxiety, depression, and mood swings. (Clapp 2017) These symptoms often coexist with adrenal dysfunction. (NIDDK 2022)

Digestive issues

Persistent digestive problems such as bloating, gas, diarrhea, constipation, and food intolerances often indicate gut dysbiosis. (Wei 2021) These issues can signal an imbalance in gut bacteria, affecting nutrient absorption and overall gut health.

Fatigue

Chronic fatigue is a hallmark symptom of adrenal dysfunction. (NIDDK 2022) Dysbiosis can contribute to fatigue by disrupting cortisol production, altering circadian rhythm, impacting sleep quality, increasing inflammation, and impairing nutrient absorption. (Rusch 2023)

Frequent infections

Since the gut and microbiome balance play a significant role in immune system balance, a compromised gut microbiome weakens the immune system, making those with dysbiosis more susceptible to infections. Frequent colds, flu, and other infections can indicate both gut and adrenal health issues. (Wiertsema 2021)

Skin problems

Conditions such as acne, eczema, and psoriasis can be linked to gut dysbiosis and chronic inflammation, both of which affect adrenal health. (Widhiati 2021) Stress can also exacerbate skin reactions. (Lambert 2022)

Conditions related to dysbiosis and adrenal dysfunction

Several conditions are associated with both gut dysbiosis and adrenal dysfunction, highlighting the interconnectedness of these systems.

Autoimmune disorders

Conditions such as rheumatoid arthritis, lupus, and inflammatory bowel disease (IBD) involve chronic inflammation and immune dysregulation. (Xiang 2023) Both dysbiosis and adrenal dysfunction can exacerbate these conditions by perpetuating inflammation and stress.

Chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a complex disorder involving severe fatigue and other symptoms. (CDC 2024) Dysbiosis and adrenal dysfunction are frequently observed in individuals with CFS, suggesting a multifactorial etiology involving gut health and stress response. (Deumer 2021)

Chronic fatigue is linked to both gut dysbiosis and adrenal dysfunction. 

Fibromyalgia

This condition is characterized by widespread musculoskeletal pain and fatigue. Similar to CFS, fibromyalgia patients are often found to have dysbiosis and HPA axis abnormalities, implicating gut-adrenal interactions. (Clos-Garcia 2019)

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common condition characterized by chronic digestive issues. It's often associated with dysbiosis and has been linked to abnormal cortisol levels and HPA axis dysfunction. (Shaikh 2023)

Lab test assessments

Accurate diagnosis is crucial for addressing microbiome imbalances and adrenal dysfunction. Various diagnostic tests can provide valuable insights to help support patient outcomes.

Hormone panels

Comprehensive hormone panels, including blood or saliva tests, evaluate adrenal hormones (cortisol, DHEA) and sex hormones (estrogen, progesterone, testosterone). These tests help assess overall endocrine function and identify imbalances affecting adrenal health. (NICHD 2017)

Organic acids test (OAT)

This test analyzes urine for organic acids, which are metabolic byproducts. It provides insights into gut dysbiosis, nutrient deficiencies, catecholamine markers, and mitochondrial function, helping to uncover underlying factors contributing to adrenal dysfunction. (Lord 2008)(Rogers 2006)

Saliva tests for cortisol

Salivary cortisol testing measures cortisol levels at different times of the day, providing a comprehensive view of adrenal function and circadian rhythm. It helps identify abnormal cortisol patterns associated with stress, adrenal fatigue, and HPA axis dysregulation. (Kobayashi 2017)(Langelaan 2018)

Stool analysis

Comprehensive stool analysis evaluates the composition and function of the gut microbiome. It identifies beneficial and pathogenic bacteria, as well as yeast overgrowth. This test helps pinpoint dysbiosis and guides targeted interventions to restore gut health. (Alagiakrishnan 2024)

Supporting microbiome and adrenal health

By recognizing the signs of microbiome imbalance and understanding its impact on adrenal function, healthcare providers can implement personalized treatment plans to restore gut health and support adrenal resilience in patients.